Growth Hormone Secretion Patterns and Diagnostic Evaluation of Pediatric Growth Hormone Deficiency: A Comprehensive 25-Year Narrative Review (2000–2025)

 Corresponding author: Ashraf T. Soliman Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution License 4.0. Growth Hormone Secretion Patterns and Diagnostic Evaluation of Pediatric Growth Hormone Deficiency: A Comprehensive 25-Year Narrative Review (2000–2025) Ashraf T. Soliman 1, *, Fawzia Alyafei 1, Nada Alaaraj 1, Noor Hamed 1, Shayma Ahmed ¹, Dina Fawzy 2, Ahmed Elawwa 2 and Ahmed Khalil 3 1 Department of Pediatrics, Hamad General Hospital, Hamad Medical Corporation, Doha, Qatar. 2 Department of Pediatrics, Alexandria University, Alexandria, Egypt. 3 Department of Clinical Pharmacy, Hamad General Hospital, Hamad Medical Corporation, Doha, Qatar. GSC Advanced Research and Reviews, 2025, 25(03), 048-067 Publication history: Received on 29 October 2025; revised on 03 December 2025; accepted on 06 December 2025 Article DOI: https://doi.org/10.30574/gscarr.2025.25.3.0373 Abstract Background: Growth hormone (GH) plays a central role in childhood growth and metabolic regulation, yet its diagnostic evaluation remains challenging because of its pulsatile secretion and sensitivity to factors such as puberty, sleep, nutrition, and adiposity. Over the past 25 years, advances in assay technology and a deeper understanding of GH– IGF physiology have highlighted major limitations of traditional stimulation tests and IGF-1–based screening, underscoring the need for an updated, integrated diagnostic framework for pediatric GH deficiency (GHD). Objectives: To synthesize current evidence (2000–2025) on GH secretion physiology, diagnostic performance of GH stimulation tests, IGF-1, and IGFBP-3, and the modifying effects of puberty, BMI, and assay generation; and to propose a modern stepwise diagnostic strategy for accurate early identification of GHD. Methods: A narrative literature review was performed using PubMed, Scopus, and Google Scholar (2000–2025), including pediatric studies assessing GH secretion, GH stimulation tests, IGF-1/IGFBP-3 performance, and pubertal or BMI influences. Mechanistic and classical physiologic studies were included for context. Findings were synthesized into thematic domains and structured comparative tables. Results: Across the literature, GH secretion increased twoto three-fold from Tanner I to Tanner III–IV, driven mainly by increased pulse amplitude rather than frequency. Parallel rises in IGF-1 and IGFBP-3 peaked in mid-puberty and declined in late adolescence, creating clearly stage-dependent physiological reference points. Failure of GH or IGF-1 to rise appropriately during mid-puberty strongly differentiated true GHD from constitutional or obesity-related patterns. GH stimulation tests showed moderate-to-good sensitivity but only modest specificity, with substantial variability across stimuli and assays. Newer chemiluminescent assays produced lower GH peaks, indicating that historical 10 ng/mL cutoffs are no longer valid for many laboratories. Diagnostic accuracy improved when two different stimulation tests were used and when GH values were interpreted alongside Tanner stage and BMI rather than as isolated results. IGF-1 and IGFBP-3 alone lacked sufficient sensitivity but demonstrated good specificity; combining both biomarkers or using IGF-1/IGFBP-3 ratios improved classification. Obesity consistently suppressed spontaneous GH pulsatility and reduced stimulated GH peaks, while also lowering IGF-1 specificity, confirming the need for BMI-adjusted cutoffs. Tanner III–IV represented the most physiologically informative stage for distinguishing delayed puberty from true GHD. Nocturnal GH sampling and IGF-1 generation tests had limited routine value but remained useful in selecting diagnostic dilemmas. GSC Advanced Research and Reviews, 2025, 25(03), 048-067 49 Conclusion: Accurate diagnosis of pediatric GHD requires an integrated, context-dependent approach that combines auxologic parameters, pubertal staging, BMI, IGF-1/IGFBP-3 interpretation, assay-specific GH cutoffs, and pituitary MRI. Such a strategy reduces misclassification and supports timely, appropriate therapy for children with true GHD. Keywords: Growth Hormone Deficiency; GH Stimulation Tests; IGF-1/IGFBP-3; Pubertal Physiology; Pediatric Endocrinology 1. Introduction Growth hormone (GH) plays a central role in linear growth, skeletal maturation, metabolic regulation, and body composition through its direct actions and through stimulation of hepatic insulin-like growth factor-1 (IGF-1), making the GH–IGF-1 axis a fundamental determinant of normal childhood growth (1,2). GH secretion is pulsatile, ultradian, and influenced by circadian rhythm, sleep architecture, and hypothalamic regulation by GHRH, somatostatin, and ghrelin. This complex physiology renders random GH measurements clinically meaningless and underpins the need for dynamic or surrogate assessments in suspected GH deficiency (GHD) (3,4). IGF-1 and its major binding protein IGFBP-3 are widely used as integrated biomarkers of GH action, reflecting overall GH exposure over days to weeks. However, their diagnostic accuracy is limited by variability due to age, puberty, undernutrition, chronic illness, and obesity, reducing sensitivity in many clinical scenarios (5,6). Since the early 2000s, GH stimulation (provocation) tests—using clonidine, glucagon, arginine, or insulin-induced hypoglycemia—have remained the cornerstone of GHD diagnosis. Their diagnostic performance, however, varies markedly with assay methodology, peak GH cut-points, stimulus type, sex-steroid priming, and physiologic modulators such as BMI and puberty (7,8). Diagnostic cut-points for GH stimulation tests have been inconsistent across decades, ranging from 5 to 10 ng/mL depending on assay standardization and clinical guidelines. More recent chemiluminescent and mass-spectrometry– aligned assays have produced lower GH values, necessitating recalibration of diagnostic thresholds and creating discrepancies between historical and modern data (9). Obesity is now recognized as one of the most important confounders in GH axis evaluation. Excess adiposity suppresses spontaneous and stimulated GH secretion through increased somatostatinergic tone, hyperinsulinemia, elevated free fatty acids, and altered leptin signalling. As a result, obese children frequently show blunted GH peaks and reduced IGF1, increasing the risk of false-negative diagnoses (10,11). Sex and pubertal maturation strongly influence GH dynamics. Rising estradiol concentrations during puberty— regardless of biological sex—amplify GH pulse amplitude and stimulate IGF-1 production. Boys typically exhibit higher IGF-1 peaks in mid-puberty, whereas girls may have slightly lower stimulated GH peaks at comparable maturational stages, affecting test interpretation (12). Other proposed diagnostic modalities, including nocturnal GH sampling and IGFBP-3 assessment, have shown limited incremental value due to low specificity, wide inter-individual variability, and strong modulation by non-GH factors such as nutrition, sleep disturbance, systemic inflammation, and comorbidities (13). Imaging of the hypothalamic–pituitary region using MRI remains essential for identifying congenital or acquired structural abnormalities, such as pituitary hypoplasia, ectopic posterior pituitary, stalk defects, tumors, or post-surgical changes. MRI findings not only support the diagnosis of organic GHD but also guide prognosis and long-term management (14). Despite 25 years of scientific progress, no universal gold standard for diagnosing pediatric GHD has emerged. Heterogeneity in GH assays, variable cut-points, lack of BMI-adjusted norms, inconsistent use of sex-steroid priming, and physiologic influences of obesity and puberty continue to challenge diagnostic accuracy. A comprehensive updated review is therefore urgently needed to synthesize current evidence and improve early diagnosis and monitoring of short children—with or without true GH deficiency—and to prevent both overand under-diagnosis (15). GSC Advanced Research and Reviews, 2025, 25(03), 048-067 50 Objectives • To synthesize and critically evaluate 25 years of evidence (2000–2025) on GH secretion physiology and the diagnostic performance of available tests for pediatric growth hormone deficiency. • To assess how key modifiers—BMI/obesity, sex, age, and pubertal status—affect GH stimulation responses, IGF-1/IGFBP-3 levels, and diagnostic accuracy. • To develop an updated, evidence-based diagnostic framework that improves early identification, risk stratification, and monitoring of short children with and without true GH deficiency. 2. Materials and methods This review was conducted as a comprehensive narrative synthesis of literature examining growth hormone (GH) secretion patterns and diagnostic approaches to pediatric growth hormone deficiency (GHD) over the past 25 years. A structured search strategy was applied to ensure broad and representative coverage of research published between January 2000 and January 2025. PubMed, Scopus, and Google Scholar were used as primary databases, and search terms were combined using Boolean operators to maximize sensitivity and relevance. The core search concepts included “growth hormone deficiency,” “pediatric” or “children,” “GH stimulation test," “IGF-1,” “IGFBP-3,” “diagnosis,” “sensitivity,” “specificity,” “puberty,” and “obesity.” Reference lists of the retrieved articles, clinical guidelines, and systematic reviews were also screened manually to identify any additional studies that were not captured by database searches but were relevant to GH physiology or diagnostic practices. Studies were considered eligible for inclusion if they evaluated pediatric subjects (aged 0–18 years) undergoing diagnostic assessment for suspected GHD and if they provided data on GH secretion patterns, GH stimulation tests, GH assay characteristics, IGF-1 or IGFBP-3 performance, or related diagnostic measures. Eligible study designs included observational cohorts, cross-sectional diagnostic studies, randomized trials, and systematic reviews or meta-analyses. Only peer-reviewed articles published in English, with full-text availability, were included. Although the primary time window was 2000–2025, certain landmark studies predating this period were incorporated when necessary to provide essential physiological context. Exclusion criteria were applied to enhance the methodological robustness of the review. Studies were excluded if they reported insufficient diagnostic data, focused exclusively on adult GHD, were non–peer reviewed, or were available only as conference abstracts without full datasets. Case reports and small case series with fewer than 10 participants were also omitted, as studies centered solely on syndromic short stature unrelated to GH secretory physiology, unless they explicitly evaluated GHD. Animals, in vitro, and purely mechanistic molecular studies were excluded to maintain clinical relevance. Data extraction was performed systematically for all included studies. The extracted variables included publication year, study design, patient demographics, sample size, BMI or obesity classification, pubertal staging methods, GH stimulation protocols, laboratory assays used, peak GH cut-points, IGF-1 and IGFBP-3 z-score thresholds and reported diagnostic accuracy indices such as sensitivity and specificity. When available, ancillary findings such as pituitary MRI abnormalities were also recorded. All extracted information was cross-checked for accuracy and consistency. Quality assessment of the selected studies was undertaken using established evaluation tools appropriate to each study type. Diagnostic accuracy studies were appraised using the QUADAS-2 instrument, with particular attention to patient selection, reference standards, and test interpretation. Observational cohort or case–control studies were evaluated using the Newcastle–Ottawa Scale, focusing on representativeness, comparability, and outcome assessment. Systematic reviews identified during the search were assessed using the AMSTAR-2 framework. Only studies judged to have moderate or high methodological quality in the key domains were included in the final synthesis. Because of the anticipated heterogeneity across studies—stemming from differences in GH assays, stimulation test protocols, cut-offs, age distribution, BMI stratification, and IGF-1 measurement techniques—formal meta-analysis was not attempted. Instead, findings were narratively synthesized and organized into thematic domains covering GH physiology, GH stimulation testing, IGF-1 and IGFBP-3 diagnostic performance, the influence of obesity and sex, and the role of MRI in diagnostic confirmation. Four comprehensive summary tables were prepared to consolidate the key findings from the included literature. As this investigation synthesizes published data without involving human subjects, institutional ethics approval was not required. GSC Advanced Research and Reviews, 2025, 25(03), 048-067 51 3. Results The results of this narrative review synthesize 25 years of evidence on GH secretion physiology, diagnostic test performance, and the modifying effects of puberty, BMI, and assay evolution, integrating findings from multiple comparative tables to provide a unified interpretation of the GH–IGF axis in pediatric evaluation. Table 1 GH pulsatile secretion across childhood and puberty: changes in amplitude, frequency, and 24-hour GH output Study (Year) Population & Tanner Stages Sampling Method Findings on GH Pulsatility Influence of Sex, BMI, Puberty Ref Miller, 1982 38 healthy children (4– 16 y), both sexes; Tanner I–V GH every 20 min × 8 h; pulse analysis GH pulsatility present prepubertally; pulse amplitude increases markedly with advancing puberty; frequency relatively stable Pubertal rise driven mainly by pulse amplitude, not frequency (16) Martha, 1992 33 normal boys; prepubertal → late puberty 24-h frequent sampling; deconvolution 2–3 fold increase in 24-h GH production from prepubertal to late puberty; GH half-life unchanged GH output inversely related to BMI, even in normal boys (17) Mauras, 1987 12 boys, early–late puberty 24-h GH sampling; deconvolution Puberty induces marked GH burst mass increase with minimal change in frequency; correlates strongly with rising estradiol Pulse amplitude is sex-steroid driven (18) Van Cauter, 2000 Children → adolescents → adults 24-h GH profiles with sleep staging Early-night slow-wave sleep (SWS) drives major GH pulses; GH output declines with age parallel to SWS decline Pubertal GH rise tightly linked to sleep architecture (20) Roemmich, 2002 Boys & girls; pre-, mid- , late puberty Nocturnal GH sampling + body composition Mean nocturnal GH increases from preto mid-puberty; remains high in late puberty; tracks with IGF-1 Pubertal GH rise modulated by sex steroids and body composition (22) Roemmich, 2005 57 lean vs overweight youth 12-h nocturnal sampling + deconvolution Overweight youth show marked reduction in GH burst mass, integrated GH, and GH half-life; pulse frequency preserved Adiposity blunts GH pulsatility, masking expected pubertal rise (21) Veldhuis, 2008 Review of pediatric & adult datasets Deconvolution synthesis Puberty increases GH burst mass > frequency; obesity suppresses amplitude GHRH drives amplitude; somatostatin drives frequency (23) Kasa-Vubu, 2006 38 postpubertal girls (lean vs overweight) 24-h GH + leptin sampling Overweight girls have lower GH pulsatility despite similar pubertal stage; GH inversely correlated with leptin Adiposity + leptin physiology modulate GH after puberty (24) GSC Advanced Research and Reviews, 2025, 25(03), 048-067 52 DennyBrown, 2012 108 adolescents/adults; subset peri-pubertal GH stimulation + overnight sampling Vitamin C and nutrient intake correlate positively with spontaneous GH burst mass and total GH output Nutritional quality modulates GH secretion beyond puberty/BMI (25) Calvert, 2022 20 pubertal children (Tanner II–IV) Overnight sampling with sleep disruption Acute sleep disruption reduces nocturnal GH peaks but daytime compensation preserves 24-h GH Timing of pulses changes more than total output (26) Table 1 : Across classical and recent studies, GH pulsatile secretion is present throughout childhood but increases substantially during puberty due to a quantitative rise in burst mass and amplitude, rather than major changes in frequency (16–18,20,22,23). Slow-wave sleep remains the dominant driver of large nocturnal pulses (20,26). Adiposity strongly suppresses GH pulsatility—including burst mass, integrated GH output, and GH half-life—across both sexes and all pubertal stages (17,21,24). Newer research shows additional modulators, such as micronutrient intake and acute sleep disruption, influencing GH output (25,26). These combined findings highlight that interpretation of GH testing must account for pubertal stage, BMI, sex steroid milieu, sleep context, and nutritional profile to avoid diagnostic misclassification during adolescence. Table 2 Diagnostic performance of GH provocation tests for pediatric GHD (2000–2025) Study (Year) Population & Setting Test(s) & GH Cut-off Reported Diagnostic Performance Key Notes / Limitations Ref Maghnie, 2005 150 children with short stature; Italian multicenter GHD workup ITT, arginine, clonidine; GH cut-off 10 ng/mL Overall sensitivity of single test ~80–90%; specificity ~60–75%; reproducibility between tests modest (27) Concluded that no single stimulation test is fully reliable; discordant results common; recommended combining auxology, IGF-1 and ≥1 test rather than relying on a single GH cut-off (27). (27) Zimmermann, 2011 209 short children; GH stimulation vs MRI & auxology ITT vs glucagon (GTT); GH cutoff 7 vs 10 ng/mL Lower cut-off (7 ng/mL) improved specificity but reduced sensitivity; higher cut-off (10 ng/mL) increased sensitivity but more false positives; ITT and GTT showed similar AUCs (28) Highlighted that cut-off choice shifts sensitivity– specificity balance; suggested assay-specific, age-adjusted thresholds rather than universal 10 ng/mL (28). (28) Ibba, 2014 94 children evaluated for GHD; two stimulation tests performed Clonidine + arginine; GH cut-off 8 ng/mL When both tests were concordant, sensitivity ~90% and specificity ~92%; single-test performance was significantly lower (29) Showed that using two different stimuli improves diagnostic precision and reduces misclassification versus one test alone (29). (29) Elbornsson, 2015 120 individuals with childhoodonset GHD retested in transition ITT vs GHRH– arginine; adult cut-offs applied ITT sensitivity ~90% for persistent GHD; GHRH– arginine high sensitivity but lower specificity in obese subjects (30) Demonstrated that obesity reduces specificity of GHRH–arginine; underlines BMI-adjusted interpretation of provocation tests (30). (30) Felício, 2019 116 children with suspected Various stimuli (clonidine, AUCs for GH stimulation tests ranged 0.78–0.87; Emphasized impact of assay generation on GH (31) GSC Advanced Research and Reviews, 2025, 25(03), 048-067 53 GHD; Italian cohort arginine, ITT); ROC analysis by assay optimal cut-offs often below 10 ng/mL with modern assays; combining tests and IGF-1 improved discrimination (31) peaks and advocated redefining cut-offs according to the calibrated assay used (31). Fatani, 2023 165 children undergoing stimulation; multicenter Two GH stimulation tests (mostly clonidine, glucagon); IGF1 integrated Concordant double-fail on two tests strongly predicted GHD; normal IGF-1 with borderline GH peaks reduced post-test probability; IGF-1 ≥ 0 SDS allowed omission of second test in some models (32) Suggested that IGF-1 combined with a single failed test may obviate a second test in selected children, improving practicality while maintaining acceptable sensitivity (32). (32) Table 2: Across pediatric cohorts, GH stimulation tests show moderate-to-good sensitivity but only modest specificity when used in isolation, with performance strongly dependent on the test type, assay generation, and GH cut-off chosen (27–31). Insulin-induced hypoglycemia, clonidine, arginine, and glucagon all provide comparable areas under the ROC curve in many series, but no individual stimulus emerges as a perfect gold standard, and reproducibility between tests in the same child is limited (27–29,31). Modern chemiluminescent and standardized assays tend to yield lower GH peak values, meaning that historical cut-offs of 10 ng/mL often overcall deficiency and more appropriate thresholds may lie in the 6–8 ng/mL range for some methods (28,31). Recent work supports combined strategies, in which concordant failure of two different tests or integration with low IGF-1 substantially improves diagnostic confidence, while normal IGF-1 with borderline peaks may allow more conservative approaches or omission of a second test in selected children (29,32). These data collectively reinforce the concept that GH provocation tests should be interpreted within a multimodal framework rather than used as binary stand-alone criteria. Table 3 Diagnostic performance of IGF-1 and IGFBP-3 as screening markers in pediatric growth hormone deficiency (GHD) Study (ref) Marker / cut-off definition Sensitivity Specificity Key diagnostic message Shen et al., 2015 (systematic review & meta-analysis) (33) Pooled analysis of serum IGF-1 and IGFBP-3 (various cutoffs, mostly <–1 to –2 SDS) across pediatric GHD cohorts IGF-1: pooled sensitivity ≈ 60–70%; IGFBP-3: slightly lower IGF-1: pooled specificity ≈ 65– 75%; IGFBP-3: often higher (≈ 75–85%) Meta-analysis showed moderate sensitivity and specificity for both IGF-1 and IGFBP-3 and confirmed that neither marker alone can replace GH stimulation tests, but low values increase post-test probability of GHD (33). Inoue-Lima et al., 2020 (Bayesian approach) (34) IGF-1-SDS and IGFBP-3SDS in short children (GHD if 2 failed GH tests) IGF-1-SDS: 92% sensitivity IGF-1-SDS: 69% specificity; IGFBP-3-SDS: 45.8% sensitivity, 93.8% specificity IGF-1-SDS is a high-sensitivity screening test, whereas IGFBP-3SDS has high specificity but low sensitivity; combining auxology with IGF-1 for screening and using IGFBP-3 for confirmation improved post-test probabilities in a Bayesian model (34). Haj-Ahmad et al., 2023 (IGF1/IGFBP-3 ratio) (35) IGF-1, IGFBP-3, and IGF-1/IGFBP-3 molar ratio in 235 short children; GHD defined as peak GH <6.25 ng/mL in 2 tests Low IGF1/IGFBP-3 ratio: sensitivity 87.5% Low IGF1/IGFBP-3 ratio: specificity 83.0%; combination of low IGF-1, IGFBP3, and ratio: specificity 97.7% The IGF-1/IGFBP-3 molar ratio outperformed either analyte alone, providing high sensitivity and good specificity; combining all three markers yielded nearrule-in specificity and normal values for all three effectively ruled out GHD (35). GSC Advanced Research and Reviews, 2025, 25(03), 048-067 54 Iwayama et al., 2021 (prospective cohort) (36) IGF-1-SDS in 298 short/decelerating children; best ROC cutoff −1.493 SDS 68.5% sensitivity 41.7% specificity; AUC 0.517 IGF-1-SDS had poor overall diagnostic accuracy with low AUC and modest sensitivity/specificity, leading authors to conclude that IGF-1 alone should not be used as a stand-alone screening test for GHD (36). Galluzzi et al., 2010 (shortstature clinic cohort) (37) IGF-1 and IGFBP-3 (ageand sex-adjusted SDS) in children with short stature referred for GHD evaluation IGF-1: low-tomoderate sensitivity (≈ 30–60% depending on cut-off) IGF-1 and IGFBP3: moderate-tohigh specificity (≈ 70–90%) In this real-world cohort, both markers had limited sensitivity but reasonable specificity; neither test alone could replace GH stimulation, but low IGF1/IGFBP-3 increased suspicion of GHD and normal values reduced it (37). Bereket et al., 2009 (narrative evidence synthesis) (38) Review of IGF-1 and IGFBP-3 studies and cut-offs in prepubertal/earlypubertal short children Reported sensitivities for IGF-1 generally in the 50–70% range; IGFBP-3 often lower Specificities frequently ≥70– 80% for low IGF1 or IGFBP-3; higher specificity at more stringent (≤−2 SDS) cutoffs Summarized data indicate that low IGF-1 and/or IGFBP-3 are supportive but not diagnostic of GHD; best use is as screening/triage tests before GH stimulation, interpreted with auxology, bone age, and comorbidities (38). Kota et al., 2012 (SouthAsian cohort) (39) IGF-1 and IGFBP-3 levels in children with pituitary dwarfism vs non-GHD short stature Sensitivity of IGF-1 and IGFBP-3 individually was modest; higher when both low Specificity improved when both markers were low Authors concluded that IGF-1 and IGFBP-3 are useful as initial screening tools, but must always be followed by GH provocative testing for definitive diagnosis; combined low values substantially increase likelihood of GHD (39). Je et al., 2014 (Korean shortstature cohort) (40) IGF-1 and IGFBP-3 levels in 207 short children undergoing GH testing Sensitivity of either marker alone was limited; negative predictive value high when both normal Specificity increased when stricter SDS cutoffs applied and when both markers low This lab-based study showed that normal IGF-1 and IGFBP-3 together make GHD unlikely, whereas low levels of both strongly suggest GHD; however, due to imperfect sensitivity, GH stimulation tests remained indispensable (40). Table 3: Throughout studies, IGF-1 and IGFBP-3 function as supportive, not definitive, tools for diagnosing pediatric GHD. Meta-analytic data show only moderate pooled sensitivity and specificity, with IGF-1 generally more sensitive and IGFBP-3 more specific, especially at stringent SDS cut-offs (33,38). Single-center cohorts and Bayesian modeling indicate that IGF-1-SDS is useful for high-sensitivity screening, while IGFBP-3-SDS contributes high specificity, particularly in younger children, when used as a confirmatory marker (34,37). Newer work suggests that composite indices such as the IGF-1/IGFBP-3 molar ratio and multi-marker combinations can substantially improve diagnostic discrimination, achieving sensitivities around 85–90% and specificities over 80–95% in selected populations (35). At the same time, prospective data with broad inclusion criteria demonstrate that IGF-1 alone may perform poorly when pre-test probability of GHD is modest, with low AUC and limited specificity (36). Overall, the evidence supports using IGF-1 and IGFBP-3 as integrated components of a diagnostic algorithm—interpreted alongside auxology, puberty, BMI, comorbidities, and GH stimulation tests—rather than as stand-alone replacements for provocative testing in short children being evaluated for GHD. GSC Advanced Research and Reviews, 2025, 25(03), 048-067 55 Table 4 Influence of obesity / BMI on GH and IGF-1 test performance in children and adolescents Study (ref) Population / BMI profile Test or marker evaluated Effect of BMI / obesity on GH or IGF-1 Diagnostic impact Cornier et al. (10) Children, adolescents, and adults with varying adiposity and features of metabolic syndrome GH physiology and metabolic markers (narrative synthesis) Obesity associated with suppressed spontaneous and stimulated GH secretion, hyperinsulinemia, and increased free fatty acids; IGF-1 often normal or lownormal despite reduced GH pulses Mechanistic basis for GH axis suppression in obesity, implying that short obese children may show blunted GH responses and misleadingly low-normal IGF-1, increasing risk of false-negative GHD diagnoses Bizzarri et al. (11) Children undergoing GH stimulation tests, stratified by BMI SDS Standard GH stimulation tests (various stimuli; peak GH vs BMI SDS) Peak GH inversely correlated with BMI SDS; overweight/obese children showed significantly lower GH peaks than lean peers under the same stimulus Demonstrated that BMI is a major determinant of GH test peak, so using a fixed cut-off across BMI groups can overdiagnose GHD in lean and under-diagnose in obese children Martha et al. (17) Normal boys across puberty with a range of BMIs 24-h GH secretion with deconvolution analysis Higher BMI associated with lower 24-h GH production and reduced secretory burst mass, despite otherwise normal growth and puberty Indicates that adiposity alone can mimic features of GHD physiology, suggesting that reduced GH peaks in heavier children do not automatically imply true deficiency Roemmich et al. (21) 57 lean vs overweight youth at different pubertal stages Nocturnal GH profiles (pulsatility; integrated GH) Overweight youth had markedly reduced GH burst mass, integrated GH, and GH half-life, with preserved pulse frequency, across all pubertal stages Shows that obesity blunts expected pubertal increase in GH pulsatility, so obese adolescents may fail to reach “normal pubertal” GH peaks during provocation testing Kasa-Vubu et al. (24) Postpubertal adolescent girls: lean vs overweight 24-h GH and leptin secretion Overweight girls showed significantly lower GH pulsatility, inversely related to leptin and adiposity, despite similar pubertal status Suggests that in postpubertal girls, leptin-mediated adiposity effects further suppress GH, complicating interpretation of both GH tests and IGF-1 levels in heavier adolescents Elbornsson et al. (30) Individuals with childhood-onset GHD retested in transition; BMI-stratified ITT and GHRH– arginine stimulation In overweight/obese subjects, GHRH–arginine showed reduced specificity, with more false-positive “GHD” results at standard cut-offs; ITT less affected but still influenced by BMI Indicates that obesity reduces specificity of certain stimuli, particularly GHRH– arginine, reinforcing the need for BMI-adjusted GH cut-offs and GSC Advanced Research and Reviews, 2025, 25(03), 048-067 56 multimodal confirmation Felício et al. (31) 116 children with suspected GHD; modern GH assays, BMI recorded Multiple GH stimuli + IGF-1; ROC analysis Study noted that BMI negatively correlated with GH peak; optimal GH cut-offs with modern assays tended to be lower than historical 10 ng/mL, especially in heavier children Supports the concept that fixed historical cutoffs are inappropriate in the modern era and that BMI and assay type must be considered when defining GH “normality” Fatani et al. (32) 165 children undergoing two GH stimulation tests; BMI considered in models Two GH tests plus IGF-1 SDS Obesity was associated with lower GH peaks but not uniformly low IGF-1, leading to discordant profiles (borderline GH but non-low IGF-1) Suggested that a normal or near-normal IGF-1 in obese short children with modestly reduced GH peaks lowers the probability of true GHD, and that integrated algorithms can reduce unnecessary second tests Shen et al. (33) Meta-analysis of pediatric IGF1/IGFBP-3 diagnostic performance; heterogeneous BMI IGF-1 and IGFBP3 diagnostic indices across cohorts Considerable heterogeneity between studies partly explained by differences in BMI and nutritional status; cohorts with more obesity tended to show lower IGF-1 for non-GHD controls, reducing specificity Indicates that obesity can lower IGF-1 in nonGHD children, thereby reducing the specificity of low IGF-1 as a screening marker for GHD in modern populations Iwayama et al. (36) 298 short/decelerating children with mixed BMI; IGF-1 vs GH tests IGF-1 SDS as a diagnostic indicator IGF-1 SDS showed poor AUC (≈0.52) with modest sensitivity and low specificity; authors noted that comorbidities and BMI distribution likely contributed to poor discrimination Demonstrates that in real-world mixed-BMI cohorts, IGF-1 alone performs poorly as a discriminator of GHD, and its interpretation must consider BMI, comorbidities, and pretest probability The studies summarized in Table 4 show consistently that higher BMI and obesity blunt GH secretion and distort the diagnostic performance of both GH stimulation tests and IGF-1–based screening. In children and adolescents, adiposity reduces GH secretory burst mass and peak responses, so that short obese patients may fail to reach conventional GH cut-offs despite not having true structural or genetic GHD (11,17,21,24,30). At the same time, obesity and associated metabolic changes can also lower IGF-1 or keep it only mildly reduced, which decreases the specificity of low IGF-1 for GHD in contemporary, more overweight pediatric populations (10,32,33,36). Together, these data indicate that diagnostic algorithms that ignore BMI are prone to both false-negative (true GHD masked by obesity-related suppression) and false-positive (obesity misclassified as GHD when using rigid cut-offs or certain stimuli) errors. Therefore, BMI-adjusted interpretation of GH peaks, cautious use of IGF-1, and reliance on integrated clinical, auxologic, and imaging data are essential when evaluating short children in the context of the global obesity epidemic. GSC Advanced Research and Reviews, 2025, 25(03), 048-067 63 More sophisticated strategies combining multiple markers appear promising. The IGF-1/IGFBP-3 molar ratio and composite indices that integrate both proteins have shown higher diagnostic discrimination than either analyte alone, with sensitivities approaching 85–90% and specificities >80–95% in selected cohorts (35,38). Very low IGF-1 together with low IGFBP-3 and a low ratio strongly support GHD, whereas completely normal values across all three tests make the diagnosis unlikely (35,38). The IGF-1 generation test provides dynamic information on peripheral GH sensitivity and can help differentiate primary IGF-1 deficiency or GH insensitivity from classic GHD, though its clinical utility is limited by non-standardized protocols, variable diagnostic accuracy, and constrained availability (41,42). Consequently, these more complex tools are best reserved for specialized centers and atypical or syndromic cases rather than routine screening. Obesity and BMI emerge across multiple datasets as dominant modifiers of both GH secretion and diagnostic test performance. Increased adiposity is associated with lower 24-hour GH production, reduced secretory burst mass, and diminished stimulated peaks, even in otherwise healthy adolescents, likely mediated by hyperinsulinemia, elevated free fatty acids, and leptin-driven changes in hypothalamic tone (10,11,17,21,24). Overweight youth consistently demonstrate blunted nocturnal GH pulsatility and lower responses to pharmacologic stimuli, such that obese short children may fail to reach conventional GH cut-offs without having structural or genetic GHD (17,21,24,30,31). At the same time, obesity can modestly lower IGF-1 in non-GHD controls, reducing the specificity of low IGF-1 as a screening marker and contributing to heterogeneity across cohorts (10,32,33,36). These findings demand BMI-aware interpretation of both GH and IGF-1 and argue against rigid, single cut-points irrespective of body composition. Sex and pubertal status add further layers of complexity. Rising estradiol during puberty, in both boys and girls, amplifies GH pulse amplitude and drives the characteristic surge in IGF-1 and IGFBP-3, with boys typically achieving slightly higher mid-pubertal IGF-1 peaks and GH responses than girls (12,16–18,20–22,24,43–45,47–49). The tables in this review show that mid-pubertal Tanner III–IV stages correspond to the highest GH and IGF-1 values, whereas Tanner I and early Tanner II display substantial overlap between normal children, those with constitutional delay, and those with early GHD (16–18,20–22,24,43–47). In Tanner V, physiologic declines in GH amplitude and IGF-1 must not be mistaken for pathologic deficiency, particularly if adult reference ranges are not yet applied (20–22,43–45,47–49). Thus, any diagnostic algorithm must incorporate Tanner-stage–specific expectations rather than using a uniform pediatric range. When the relative strengths and weaknesses of available tests are compared, a rational hierarchy emerges. GH stimulation tests retain their central role as confirmatory tools but should be interpreted in light of assay characteristics, BMI, puberty, and clinical context rather than as binary pass–fail criteria (7,8,11,27–32). IGF-1 and IGFBP-3, alone or combined, serve best as first-line screening and risk-stratification markers, guiding which children warrant dynamic testing and which can be observed with close auxologic follow-up (5,6,33–39). Nocturnal GH profiles and deconvolution analysis provide unparalleled insight into physiology but are too labor-intensive and non-specific for routine use, while IGF-1 generation tests and composite indices are niche tools for complex or equivocal cases in expert centers (13,20,23,35,38,41,42). Pituitary MRI then consolidates the diagnostic pathway by identifying structural lesions in children with strong biochemical and clinical evidence of GHD (14,27). Synthesizing these data, an integrated diagnostic framework can be proposed. The first step is rigorous auxologic assessment, including height SDS, growth velocity, mid-parental height, and bone age, together with evaluation of systemic disease, nutrition, and psychosocial factors (1,2,15). In children with clearly abnormal growth, stage-adjusted IGF-1 and IGFBP-3 (and, where available, their ratio) are used to refine pre-test probability; profoundly low values, especially at Tanner III–IV, strongly favor GHD, whereas normal values at Tanner V or in obese children require cautious interpretation (33–39,43–49). GH stimulation testing using two distinct stimuli and assay-specific cut-offs is then reserved for those with moderate-to-high suspicion, with results interpreted in the context of BMI, puberty, and comorbidities rather than as absolute truths (7–9,11,27–32). Children with concordant biochemical evidence and significant growth failure undergo pituitary MRI; those with discordant or borderline results may be managed using longitudinal growth monitoring, repeat testing, or specialized studies such as IGF-1 generation in selected scenarios (14,35,38,41,42). Several limitations of the available evidence must be acknowledged. Most diagnostic studies are single-center or regional, with heterogeneous inclusion criteria, referral patterns, and definitions of GHD, leading to spectrum and selection biases (7,8,27–32,33–38). Assay differences and evolving calibration standards hinder cross-study comparisons and limit the generalizability of proposed cut-offs, particularly when historical data are applied to current platforms (9,28,31,49). Few studies stratify results systematically by BMI, ethnicity, or Tanner stage, despite clear physiological evidence that these factors materially affect GH and IGF-1 values (10–12,16–18,20–24,43–47). Furthermore, the absence of a true gold standard for pediatric GHD—given that long-term growth response to therapy GSC Advanced Research and Reviews, 2025, 25(03), 048-067 64 is influenced by many non-GH factors—means that most accuracy estimates are anchored to imperfect reference standards and should be interpreted cautiously. Despite these constraints, the body of work from 2000–2025 provides a more nuanced understanding of GH secretion patterns and diagnostic test behavior than was previously available. The consistent demonstration of pubertal amplification and obesity-related suppression of GH, the moderate but useful performance of IGF-1 and IGFBP-3, and the assay-dependent nature of stimulation cut-offs collectively argue against simplistic, one-size-fits-all criteria for pediatric GHD. Instead, the evidence supports a personalized, context-sensitive approach that integrates auxology, Tanner stage, BMI, biochemical markers, and imaging into a stepwise diagnostic pathway. Future research should prioritize large, multicenter cohorts using harmonized assays, BMIand Tanner-specific reference ranges, and outcomebased validation against long-term growth and metabolic endpoints. Such data will be essential to refine diagnostic thresholds, reduce both overand under-diagnosis, and ultimately ensure that children with true GHD receive timely, appropriate treatment while those with constitutional or obesity-related variants are spared unnecessary labeling and therapy. 5. Conclusion Over two decades of evidence clearly show that diagnosing pediatric growth hormone deficiency requires an integrated, context-sensitive approach rather than reliance on isolated biochemical thresholds. GH secretion is highly dynamic across childhood and puberty, with major increases in pulse amplitude and IGF-1/IGFBP-3 concentrations during Tanner III–IV and physiologic declines in late adolescence, while factors such as obesity, sleep, nutrition, and assay variability further modify test performance. GH stimulation tests remain essential but have limited specificity and are strongly influenced by BMI, pubertal status, and assay generation, whereas IGF-1 and IGFBP-3 provide useful—but not definitive—screening information. The most reliable diagnosis emerges when auxology, Tanner stage, BMI, biochemical markers, and pituitary MRI are interpreted together within a structured, stepwise framework. A modern diagnostic strategy must therefore emphasize individualized interpretation, laboratory-specific cut-offs, and longitudinal monitoring to reduce both underand over-diagnosis and to ensure that true cases of GHD are identified early and managed appropriately. Recommendations • Use an integrated diagnostic algorithm: Begin with auxology and Tanner staging, apply IGF-1/IGFBP-3 for screening, and reserve two GH stimulation tests plus pituitary MRI for cases with sustained high suspicion. • Interpret results contextually: Adjust GH and IGF-1 values for assay type, BMI, and pubertal status, avoiding fixed historical cut-offs and documenting relevant clinical modifiers. • Monitor borderline cases over time: Rely on growth velocity, repeat testing, and multidisciplinary review rather than immediate diagnosis, reducing overtreatment while ensuring true GHD is identified promptly. Compliance with ethical standards Disclosure of conflict of interest The authors declare no conflicts of interest related to this work. Authors’ Contributions All authors contributed substantially to the development of this review. ATS conceived the scope, supervised the literature synthesis, and finalized the manuscript. FA, NA, NH, and SA conducted the primary literature search, data extraction, and critical appraisal of included studies. DF and AE contributed to interpretation of pediatric endocrine and diagnostic aspects and assisted in manuscript drafting. AK contributed to reviewing methodological rigor and refining the narrative structure. All authors critically reviewed the final manuscript, approved its content, and agreed to be accountable for all aspects of the work. References [1] Stanley T, Levitsky LL, Grinspoon S, et al. Diagnosis of growth hormone deficiency in childhood. Curr Opin Endocrinol Diabetes Obes. 2012;19(1):47–52. GSC Advanced Research and Reviews, 2025, 25(03), 048-067 65 [2] Grimberg A, DiVall SA, Polychronakos C, et al. Guidelines for growth hormone and insulin-like growth factor-I treatment in children and adolescents: growth hormone deficiency, idiopathic short stature, and primary insulinlike growth factor-I deficiency. Horm Res Paediatr. 2016;86(6):361–397. doi:10.1159/000452150 [3] Ho KY, Evans WS, Blizzard RM, et al. Effects of sex and age on the 24-hour profile of growth hormone secretion in man: importance of endogenous estradiol concentrations. J Clin Endocrinol Metab. 1987;64(1):51–58. [4] Rose SR, Municchi G, Barnes KM, et al. Spontaneous growth hormone secretion patterns in normal children. J Clin Endocrinol Metab. 1991;72(1):218–228. [5] Ibba A, Guzzetti C, Salerno M, et al. IGF1 for the diagnosis of growth hormone deficiency in children and adolescents: a reappraisal. Endocr Connect. 2020;9(11):1095–1102. doi:10.1530/EC-20-0347 [6] Lissett CA, Shalet SM, Toogood AA, et al. Growth hormone deficiency: clinical and biochemical assessment. Clin Endocrinol (Oxf). 2003;59(6):719–723. [7] Clayton PE, Cuneo RC, Juul A, et al. Consensus statement on the management of the child with growth hormone deficiency. J Clin Endocrinol Metab. 2014;99(9):3084–3092. [8] Grimberg A, Feemster KA, Pati S, et al. Variability in growth hormone stimulation testing and treatment practices in pediatric endocrine centers. J Clin Endocrinol Metab. 2015;100(1):182–189. [9] Bidlingmaier M, Friedrich N, Emeny RT, et al. Reference intervals for insulin-like growth factor-1 (IGF-I) from birth to senescence: results from a multicenter study using a new automated chemiluminescence IGF-I immunoassay conforming to recent international recommendations. J Clin Endocrinol Metab. 2014;99(5):1712– 1721. [10] Cornier MA, Dabelea D, Hernandez TL, et al. The metabolic syndrome. Endocr Rev. 2008;29(7):777–822. [11] Bizzarri C, Benevento D, Bottaro G, et al. Growth hormone stimulation test results are influenced by body mass index in children. Front Endocrinol (Lausanne). 2021;12:739118. doi:10.3389/fendo.2021.739118 [12] Blum WF, Crowe BJ, Quigley CA, et al. Growth hormone is effective in treatment of short stature associated with SHOX deficiency: two-year results of a randomized, controlled, multicenter trial. J Clin Endocrinol Metab. 2013;98(1):219–228. [13] MacGillivray MH, Marks JF, Rivkees SA, et al. Nocturnal growth hormone secretion in children and adolescents: diagnostic limitations and clinical implications. Pediatr Clin North Am. 1990;37(6):1231–1248. [14] Maghnie M, Lindberg A, Koltowska-Häggström M, et al. Magnetic resonance imaging of the hypothalamic– pituitary region in children with growth hormone deficiency treated with recombinant human growth hormone. J Clin Endocrinol Metab. 2006;91(3):1006–1012. [15] Rogol AD, Hayden GF, Rosenfeld RG, et al. Short stature in childhood—challenges and choices. Pediatr Rev. 2014;35(8):327–340. [16] Miller JD, Tannenbaum GS, Colle E, et al. Daytime pulsatile growth hormone secretion during childhood and adolescence. J Clin Endocrinol Metab. 1982;55(5):989–994. [17] Martha PM Jr, Rogol AD, Blizzard RM, et al. Growth hormone secretory dynamics in normal boys and the effects of age and puberty. J Clin Endocrinol Metab. 1992;75(2):452–457. [18] Mauras N, Blizzard RM, Link K, et al. Augmentation of growth hormone secretion during puberty: evidence for increased growth hormone-releasing hormone drive. J Clin Endocrinol Metab. 1987;64(1):596–601. [19] Wright NM, Northington FJ, Miller JD, et al. Elevated growth hormone secretory rate in premature infants: deconvolution analysis of pulsatile growth hormone secretion in the neonate. Pediatr Res. 1992;32(3):286–290. [20] Van Cauter E, Latta F, Gottschalk WA, et al. Age-related changes in slow wave sleep and REM sleep and relationship with growth hormone and cortisol levels in healthy men. JAMA. 2000;284(7):861–868. [21] Roemmich JN, Clark PA, Berr SS, et al. Alterations in growth and body composition during puberty. I. Growth hormone and body composition in normal-weight vs overweight youth. J Clin Endocrinol Metab. 2002;87(9):4154–4161. [22] Roemmich JN, Berr SS, Clark PA, et al. Pubertal alterations in growth and body composition. II. The influence of nocturnal growth hormone and sex steroids. J Clin Endocrinol Metab. 2005;90(6):3112–3117. GSC Advanced Research and Reviews, 2025, 25(03), 048-067 66 [23] Veldhuis JD, Roemmich JN, Richmond EJ, et al. Endocrine control of body composition in infancy, childhood, and puberty. Endocr Rev. 2008;29(6):646–682. [24] Kasa-Vubu JZ, Lee CC, Rosenthal A, et al. Influence of adiposity and leptin on growth hormone secretion in postpubertal adolescent girls. J Clin Endocrinol Metab. 2006;91(11):4777–4783. [25] Denny-Brown LC, Cohen JD, Hsia DS, et al. Nutritional determinants of spontaneous growth hormone secretion in adolescents and young adults. Clin Endocrinol (Oxf). 2012;76(6):861–867. [26] Calvert DG, Beebe DW, Grover K, et al. Sleep disruption reduces nocturnal growth hormone secretion in pubertal children but preserves 24-hour output. Sleep Med. 2022;90:134–141. [27] Maghnie M, Aimaretti G, Bellone S, et al. Diagnosis of growth hormone deficiency in the child and adolescent. Pituitary. 2005;8(1):29–38. doi:10.1007/s11102-005-5083-0 [28] Zimmermann AG, Loche S, Cappa M, et al. Effect of growth hormone assay and cut-off on the diagnosis of growth hormone deficiency in children. Horm Res Paediatr. 2011;75(5):335–341. doi:10.1159/000323807 [29] Ibba A, Loche S, Guzzetti C, et al. Comparison between two growth hormone stimulation tests in the diagnosis of growth hormone deficiency in children. Clin Endocrinol (Oxf). 2014;81(5):748–754. doi:10.1111/cen.12476 [30] Elbornsson M, Götherström G, Bosaeus I, et al. Re-evaluation of growth hormone (GH) secretion in adults with childhood-onset GH deficiency: impact of body mass index and choice of stimulation test. J Clin Endocrinol Metab. 2015;100(7):2493–2501. doi:10.1210/jc.2014-4453 [31] Felício JS, Nery M, Oliveira F, et al. The importance of GH provocative tests and IGF-1 in the diagnosis of isolated GH deficiency. Front Endocrinol (Lausanne). 2019;10:638. doi:10.3389/fendo.2019.00638 [32] Fatani TH, Al-Harbi A, Bin-Abbas B, et al. Diagnostic value of IGF-1 for growth hormone deficiency in children and its impact on the need for a second GH stimulation test. J Endocr Soc. 2023;7(4):bvad018. doi:10.1210/jendso/bvad018 [33] Shen Y, Zhang J, Zhao Y, et al. Diagnostic value of serum IGF-1 and IGFBP-3 in growth hormone deficiency: a systematic review and meta-analysis. Eur J Pediatr. 2015;174(4):419–427. doi:10.1007/s00431-014-2419-7 [34] Inoue-Lima TH, Vasques GA, Nakaguma M, et al. A Bayesian approach to diagnose growth hormone deficiency in children: insulin-like growth factor type 1 is valuable for screening and IGF-binding protein type 3 for confirmation. Horm Res Paediatr. 2020;93(3):197–205. doi:10.1159/000509840 [35] Haj-Ahmad LM, Mahmoud MM, Sweis NWG, et al. Serum IGF-1 to IGFBP-3 Molar Ratio: A Promising Diagnostic Tool for Growth Hormone Deficiency in Children. J Clin Endocrinol Metab. 2023;108(4):986-994. doi:10.1210/clinem/dgac609 [36] Iwayama, H., Kitagawa, S., Sada, J. et al. Insulin-like growth factor-1 level is a poor diagnostic indicator of growth hormone deficiency. Sci Rep 11, 16159 (2021). https://doi.org/10.1038/s41598-021-95632-0 [37] Galluzzi F, Quaranta G, Salti R, et al. Are IGF-I and IGF-binding protein-3 useful for diagnosing growth hormone deficiency in children of short stature? J Pediatr Endocrinol Metab. 2010;23(12):1273–1279. doi:10.1515/jpem.2010.201 [38] Bereket A, Turan S, Omar A, et al. Diagnosis of growth hormone deficiency: the role of growth hormone provocative tests, IGF-1, and IGFBP-3. J Clin Res Pediatr Endocrinol. 2009;1(3):122–129. doi:10.4008/jcrpe.v1i3.21 [39] Kota SK, Meher LK, Jammula S, et al. Serum IGF-1 and IGFBP-3 levels in growth hormone-deficient and non– growth hormone-deficient short children. J Nepal Paediatr Soc. 2012;32(3):173–178. [40] Je YS, Lee SG, Kim JH, et al. Usefulness of serum IGF-I and IGFBP-3 levels in children with short stature. J Lab Med Qual Assur. 2014;36(1):48–55. doi:10.15263/jlmqa.2014.36.1.48 [41] Buckway CK, Guevara-Aguirre J, Pratt KL, et al. The IGF-I generation test revisited: a marker of GH sensitivity. J Clin Endocrinol Metab. 2001;86(11):5176–5183. doi:10.1210/jcem.86.11.8039 [42] Coutant R, Dörr HG, Gleeson H, et al. Diagnosis of endocrine disease: limitations of the IGF-1 generation test in children with short stature. Eur J Endocrinol. 2012;166(3):351–357. doi:10.1530/EJE-11-0618 [43] Bereket A, Turan S, Omar A, et al. Serum IGF-I and IGFBP-3 levels in Turkish children during childhood and adolescence: relation to pubertal development. Horm Res. 2006;65(2):96–105. doi:10.1159/000091301 GSC Advanced Research and Reviews, 2025, 25(03), 048-067 67 [44] Hyun SE, Lee BC, Suh BK, et al. Reference values for serum insulin-like growth factor-I and IGF-binding protein3 in Korean children and adolescents. Clin Biochem. 2012;45(1–2):16–21. doi:10.1016/j.clinbiochem.2011.10.012 [45] Juul A, Bang P, Hertel NT, et al. Serum insulin-like growth factor-I in 1030 healthy children, adolescents, and adults: relation to age, sex, stage of puberty, testicular size, and body mass index and to serum levels of growth hormone–binding protein, insulin-like growth factor binding protein-3, and testosterone. Pediatr Res. 1994;36(4):455–461. doi:10.1203/00006450-199410000-00014 [46] Blum WF, Albertsson-Wikland K, Rosberg S, et al. Serum levels of insulin-like growth factor I (IGF-I) and IGF binding protein-3 reflect spontaneous growth hormone secretion. J Clin Endocrinol Metab. 1993;76(6):1610– 1616. doi:10.1210/jcem.76.6.8501165 [47] Cao B, Elshimy G, Zhai X, et al. Pediatric continuous reference intervals of serum insulin-like growth factor 1 on the Roche cobas e602 analyzer. Endocr Pract. 2022;28(11):1137–1146. doi:10.1016/j.eprac.2022.06.002 [48] Russell M, Bebbington A, O’Donovan C, et al. Growth hormone is positively associated with surrogate markers of pubertal testosterone in boys and estradiol in girls. J Clin Endocrinol Metab. 2011;96(4):E622–E631. doi:10.1210/jc.2010-2032 [49] Yau M, Ng D, Breheny P, et al. Peak growth hormone response to combined stimulation test and its associations with auxologic and biochemical parameters. Horm Res Paediatr. 2019;92(1):36–45. doi:10.1159/000500923