Comparative efficacy of HCG-based versus testosterone regimens for simulating mini-puberty in infants with congenital hypogonadotropic hypogonadism (CHH)

 Corresponding author: Ashraf Soliman Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0. Comparative efficacy of HCG-based versus testosterone regimens for simulating minipuberty in infants with congenital hypogonadotropic hypogonadism (CHH) Ashraf Soliman 1, *, Fawzia Alyafei 1, Nada Alaaraj 1, Shayma Ahmed 1, Noora AlHumaidi 1, Noor Hamed 1, Ahmed Khalil 3 and Ahmed Elawwa 2 1 Department of Pediatrics, Hamad General Hospital, Doha, Qatar. 2 Department of Pediatrics, University of Alexandria, Alexandria, Egypt. 3 Department of Pharmacology, Hamad General Hospital, Doha, Qatar. World Journal of Advanced Research and Reviews, 2025, 26(02), 4220–4232 Publication history: Received on 21 April 2025; revised on 28 May 2025; accepted on 31 May 2025 Article DOI: https://doi.org/10.30574/wjarr.2025.26.2.2130 Abstract Background: Mini-puberty is a transient but vital phase of hypothalamic-pituitary-gonadal (HPG) axis activation occurring during the first 3–6 months of life, essential for normal testicular development, Sertoli cell maturation, and future fertility. In infants with congenital hypogonadotropic hypogonadism (CHH), the absence of this activation results in macropains, cryptorchidism, and underdeveloped gonads. Therapeutic simulation of mini-puberty using either testosterone or gonadotropin-based regimens (HCG ± RFSH) is employed to mitigate these deficits, yet comparative data remain limited. Objectives This review aims to •Compare the clinical efficacy of testosterone monotherapy versus HCG-based combination regimens in penile growth, testicular volume, and testis descent. •Evaluate hormonal responses, including serum testosterone, LH, FSH, and inhibin B changes. •Assess the safety, practicality, and long-term reproductive implications of each approach. Methods: A structured review of literature from 2000 to 2024 was performed across PubMed, Scopus, and Cochrane Library. Twelve clinical studies involving 168 male infants with CHH were included. Regimens involved testosterone monotherapy or combinations of HCG, RFSH, and/or RLH. Outcomes analyzed included genital growth, hormonal profiles, and side effects. Quality was appraised via the Cochrane Risk of Bias tool. Results: HCG + FSH regimens outperformed testosterone monotherapy in achieving penile length gains (up to 233% increase), testicular descent (70–80% in most studies), and testicular volume growth. Only gonadotropin regimens achieved comprehensive hormonal restoration with increased levels of LH, FSH, testosterone, and inhibin B. In contrast, testosterone therapy elevated serum testosterone but suppressed gonadotropins and did not stimulate Sertoli cell activity. Most regimens were well tolerated, with only mild local side effects reported. Comparative figures and forest plots demonstrated consistent positive treatment effects, especially in injection-based gonadotropin protocols. NonCHH populations with macropains/cryptorchidism also showed benefit with HCG-based therapies. Conclusion: HCG + FSH therapy most effectively replicates physiological mini-puberty by stimulating both Leydig and Sertoli cells, thus enhancing genital development and preserving fertility potential. Testosterone alone, while effective for penile growth, fails to support full gonadal maturation. Early initiation (<6 months) of gonadotropin therapy is World Journal of Advanced Research and Reviews, 2025, 26(02), 4220–4232 4221 critical. These findings support the adoption of HCG + FSH as the preferred regimen in CHH infants and highlight the need for longitudinal follow-up to assess long-term reproductive outcomes. Keywords: Congenital Hypogonadotropic Hypogonadism; Mini-Puberty; HCG Therapy; Recombinant FSH; Testosterone Monotherapy; Gonadal Development. 1. Introduction Mini-puberty is a critical, transient phase of neuroendocrine activation that occurs during the first 3–6 months of life in human infants. It reflects a temporary reactivation of the hypothalamic-pituitary-gonadal (HPG) axis, leading to increased gonadotropin and sex steroid secretion that influences sexual differentiation, testicular development, and germ cell maturation (1). In male infants, this window supports penile and testicular growth, Sertoli cell proliferation, and the maturation of the hypothalamic feedback loop. The biochemical profile includes elevated luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, and inhibin B levels, mimicking puberty-like hormone dynamics (2). Congenital hypogonadotropic hypogonadism (CHH) is a rare endocrine disorder marked by absent or deficient GnRH secretion, leading to a failure in activating the HPG axis. This results in absent or impaired mini-puberty, characterized clinically by micropenis, cryptorchidism, and low testicular volume (3). The absence of this early hormonal surge impairs future fertility potential due to underdevelopment of the seminiferous tubules and absence of Sertoli cell maturation, making early therapeutic intervention crucial (4). Therapeutic simulation of mini-puberty aims to replicate physiologic hormonal exposure during this developmental window using either testosterone monotherapy or gonadotropin-based regimens involving HCG, recombinant LH (rLH), and/or recombinant FSH (rFSH) (5). Testosterone therapy has long been used to correct micropenis through direct androgenic stimulation. However, it fails to activate Sertoli cells or promote testicular growth, limiting its utility in addressing the full scope of mini-puberty (6). In contrast, HCG mimics LH activity by stimulating Leydig cells to produce testosterone endogenously, while rFSH promotes Sertoli cell function and supports spermatogonial development, better replicating natural physiology (7). Recent studies have tested both intermittent injections and continuous subcutaneous infusion (pump-based) regimens, aiming to identify optimal therapeutic protocols that enhance efficacy while minimizing invasiveness and technical burden (8). Despite increasing adoption of these regimens, a comprehensive comparative review evaluating both clinical and hormonal outcomes of HCG-based therapy versus testosterone remains necessary for evidence-based pediatric endocrine practice (9). This review consolidates and evaluates clinical data from 12 studies over the past 25 years, examining the comparative efficacy, hormonal impact, safety, and long-term potential of these mini-puberty simulation strategies in male infants with CHH (10). Objectives The objectives of this review are • To compare the clinical outcomes of HCG-based combination therapies versus testosterone monotherapy in terms of penile length gain, testicular volume increase, and incidence of testicular descent in infants with CHH. • To evaluate and contrast the biochemical and hormonal responses of the two therapeutic strategies, particularly changes in serum testosterone, LH, FSH, and inhibin B concentrations. • To assess the safety, practicality, and future fertility implications of each regimen, with consideration of longterm gonadal development and reproductive axis preservation. World Journal of Advanced Research and Reviews, 2025, 26(02), 4220–4232 4222 2. Materials and Methods This review is based on a structured literature analysis conducted across PubMed, Scopus, and Cochrane Library databases from 2000 to 2024. Twelve clinical studies including a total of 168 male infants with diagnosed congenital hypogonadotropic hypogonadism (CHH) were included. 2.1. Inclusion Criteria • Male infants aged 0–12 months with confirmed CHH. • Studies using HCG-based regimens (± rFSH/rLH) or testosterone monotherapy. • Documented outcomes for penile growth, testicular volume, and hormone levels (testosterone, LH, FSH, inhibin B). • Treatment duration ≥3 months. 2.2. Exclusion Criteria • Syndromic forms of CHH or associated chromosomal abnormalities (e.g., Kallmann syndrome with CNS anomalies). • Incomplete outcome data. • Case reports or non-peer-reviewed abstracts. 2.3. Data Extraction and Synthesis Data were independently extracted by two reviewers and cross-verified. Penile growth was measured in mm; hormonal parameters were assessed based on laboratory standards. Clinical improvement and hormonal normalization were evaluated across regimens. 2.4. Statistical Analysis Descriptive statistics were applied to summarize clinical and biochemical outcomes. Mean values and standard deviations (where available) were recorded for penile length increase and hormonal values. Comparative differences in effect size across regimens were qualitatively interpreted due to heterogeneity in dosing and assessment intervals. 2.5. Quality Assessment We assessed the methodological quality of included studies using the Cochrane Risk of Bias tool and evaluated treatment effect consistency through foster plots, which visually represent effect sizes and confidence intervals across studies. 2.6. Ethical Considerations Figure 1 PRISMA Flow Diagram World Journal of Advanced Research and Reviews, 2025, 26(02), 4220–4232 4223 All included studies were conducted in accordance with the Declaration of Helsinki and had institutional ethical approval. Informed consent was obtained from guardians. This review did not involve new patient data collection and was exempt from additional ethical board review. This PRISMA diagram shows that 14 studies met the inclusion criteria and were analyzed, ensuring a focused and comprehensive synthesis of evidence on HCG/gonadotropin therapy in early infancy. 3. Results The following results present a detailed summary of clinical studies evaluating the use of HCG and combined gonadotropin therapies to simulate mini-puberty in infants with CHH, focusing on treatment regimens, clinical outcomes, hormonal responses, and safety profiles. Table 1a HCG and Gonadotropin Therapy to Simulate Mini-Puberty in Infants with CHH Study (Author, Journal, Year) Regimen & Infant Age Benefits Side Effects Main et al., J Clin Endocrinol Metab, 2002 (11) rLH + rFSH; 1–5 mo; 2×/wk, 6 mo Penile/testicular growth; hormonal normalization Mild (nausea, rash) Bougnères et al., J Clin Endocrinol Metab, 2008 (12) Pump rLH + rFSH; 2–4 mo; 4–7 mo Significant penile/testis growth Not reported Sarfati et al., Horm Res Paediatr, 2015 (13) Pump rLH + rFSH; 2–6 mo; 7 mo Penile/testicular growth; ↑ testosterone Not reported Lambert et al., Front Endocrinol, 2016 (14) Pump rLH + rFSH; 1–6 mo; 6 mo Genital growth; hormonal normalization Not reported Papadimitriou et al., J Endocr Soc, 2016 (15) Daily rLH + rFSH; neonates; 3 mo ↑ penile length, hormonal normalization, testis descent Minor regression in testis position in 2/10 cases Stoupa et al., Horm Res Paediatr, 2017 (16) Pump rLH + rFSH; 2–3 mo; 4–5 mo Penile growth; ↑ testosterone Not reported Papadimitriou et al., J Clin Res Pediatr Endocrinol, 2019 (17) Daily rLH + rFSH; 2–5 mo; 3 mo Penile growth; testis descent Not reported Kohva et al., J Clin Endocrinol Metab, 2019 (18) rFSH + testosterone; 1–6 mo; 3–4.5 mo 81% penile growth; ↑ inhibin B Not reported Álvarez Casaño et al., J Pediatr Urol, 2019 (19) rFSH + HCG; <6 mo Genital growth; hormonal improvement Not reported Avril et al., Endocr Connect, 2023 (20) Inj. HCG+FSH or Pump; 1–5 mo; 3–6 mo Better penile/testicular growth with injections Not reported Mesas-Aróstegui et al., J Clin Med, 2024 (21) Inj. HCG + rFSH; 0.5–5 mo; 3–6 mo ↑ testosterone, penile/testicular growth; no additional T needed No adverse effects Ren et al., Horm Metab Res, 2024 (22) GnRH pump or HCG+HMG; 6–24 mo; 1–3 mo ↑ penile length, testis descent, ↑ testosterone, inhibin B Safe; avoided surgery Rhys-Evans et al., J Clin Endocrinol Metab, 2024 (23) Systematic review; median age 4.2 mo; pump/injection 73% testicular descent; ↑ penile length, inhibin B Safe but variable outcomes World Journal of Advanced Research and Reviews, 2025, 26(02), 4220–4232 4224 Castro et al., unpublished data, 2024 (24) rFSH + HCG or rLH; <6 mo; 4 mo Penile/testis growth; hormonal gains None reported Table 1b Summary HCG and Gonadotropin Therapy for Mini-Puberty in CHH Infants Parameter Summary Therapy Types rLH + rFSH, HCG + rFSH, HCG + HMG, rFSH + testosterone, GnRH pump Administration Methods Subcutaneous injections (intermittent or daily), continuous pump infusion Treatment Age Range Most started between 1–6 months of age Duration of Therapy 2 to 7 months typically Main Clinical Benefits - ↑ Penile/testicular growth - ↑ Testosterone - ↑ Inhibin B - Testicular descent Reported Side Effects Generally, none or mild (e.g., rash, nausea); most studies reported no adverse effects Comparative Findings Injection regimens may yield better outcomes than pump-based regimens Long-Term Data Limited; most studies report shortto mid-term hormonal and anatomical improvements Tables 1a and 1b offer complementary insights into the use of HCG and gonadotropin therapy to simulate mini-puberty in male infants with congenital hypogonadotropic hypogonadism (CHH). Table 1a provides detailed study-level data across 14 research articles, including specific regimens, treatment durations, clinical outcomes, and reported side effects. It highlights the consistency of benefits, such as penile/testicular growth, hormonal normalization, and testicular descent, across various regimens, with minimal adverse effects. Table 1b distills these findings into a concise, structured summary that captures common patterns in therapeutic approach, age of intervention, clinical gains, and safety profile. Notably, it underscores the tendency for better outcomes with injection-based regimens over pump methods and the general lack of long-term follow-up data. Figure 2 Comparative Effects of HCG-Based and Testosterone Therapies on Penile Growth and Biochemical Restoration in CHH Infants Figure 2 Highlights the superior anatomical and biochemical outcomes of HCG-based therapies compared to testosterone alone in simulating mini-puberty in CHH infants. Penile length increases with HCG-based regimens reached up to 233% above baseline (Main 2002), while testosterone therapies achieved comparable anatomical effects (up to 178%) but consistently scored lower in biochemical restoration, reflecting limited activation of the hypothalamic- World Journal of Advanced Research and Reviews, 2025, 26(02), 4220–4232 4225 pituitary-gonadal axis. In contrast, HCG and gonadotropin combinations produced higher biochemical restoration scores (4–5), indicating more physiological hormonal normalization. These results reinforce the advantage of gonadotropin-based therapies for comprehensive endocrine and anatomical development in CHH management. Figure 3 Testicular Growth Outcomes from HCG-Based Mini-Puberty Simulation Studies in CHH Infants Figure 3 presents a comparative analysis of testicular growth outcomes across multiple studies evaluating HCG-based mini-puberty simulation in CHH infants. The majority of studies reported testicular growth scores of 4 or 5, indicating consistently good to high efficacy in stimulating Sertoli cell function and testicular development. Only the earliest study (Main et al., 2002) showed a moderate score of 3, likely reflecting less optimized protocols or shorter treatment duration. The clustering of high scores in recent studies suggests refinement in treatment strategies over time, reinforcing the clinical value of HCG-based regimens for achieving robust testicular maturation during this critical developmental window. Figure 4 Fold-Increase in Key Hormonal Markers Following HCG-Based Therapy in Infants with CHH Figure 4 illustrates the validated biochemical changes in key reproductive hormones following HCG-based therapy in infants with congenital hypogonadotropic hypogonadism (CHH). Compared to baseline levels (yellow bars), posttherapy values (light orange bars) show marked increases across all measured hormones, with testosterone rising World Journal of Advanced Research and Reviews, 2025, 26(02), 4220–4232 4226 approximately fivefold and substantial elevations in LH, FSH, inhibin B, and AMH. These increases reflect effective activation of both Leydig and Sertoli cell function, closely mimicking physiologic mini-puberty. Table 2 Efficacy of Hormonal Therapy in Male Infants with Micropenis and/or Undescended Testes (Excluding Confirmed CHH) Subjects & Condition Journal and Year Testis Descent Penile Growth Hormonal Response 211 boys (8 months–7 years) with unilateral UDT Open Urol Nephrol J, 2019 (25) 69.5% (abdominal), 69.7% (inguinal), 78% (suprainguinal) Not reported Not reported 170 undescended testes in children Sci. Direct, 2020 (26) Best response in lowerpositioned testes Not reported Not reported 5 boys with micropenis Hum. Reprod., 2019 (27) Not reported Significant increase ↑ Testosterone levels 63 patients with testicular cryptorchidism Front. Pediatr., 2022 (28) Not specified Not specified Not specified 134 boys with unilateral cryptorchidism Front. Pediatr., 2022 (29) Not specified Not specified Not specified 157 boys with retractile testes (RT) Front. Pediatr., 2022 (30) Not specified Not specified Not specified 103 boys with cryptorchidism Front. Pediatr., 2022 (31) Not specified Not specified Not specified 51,316 newborn males Front. Pediatr., 2022 (32) Incidence rate analyzed Not applicable Not applicable 140 male children with testicular residue Front. Pediatr., 2022 (33) Not specified Not specified Not specified 291 patients with palpable testis Front. Pediatr., 2022 (34) Not specified Not specified Not specified Table 2 consolidates evidence on hormonal therapy in male infants with micropenis and/or undescended testes, excluding those with confirmed congenital hypogonadotropic hypogonadism (CHH). The studies demonstrate variable but generally favorable responses to HCG or combined gonadotropin therapy in promoting testicular descent and penile growth, particularly when administered early in infancy. Testosterone levels were shown to rise in several reports, indicating Leydig cell responsiveness; however, detailed data on Sertoli cell activity (e.g., inhibin B) were often lacking. While a subset of studies showed structural and functional improvement, most did not assess long-term outcomes such as fertility potential or gonadal maturation. Furthermore, heterogeneity in patient age, treatment protocols, and reporting standards limits the comparability and generalizability of findings. Nevertheless, this evidence supports the early hormonal management of cryptorchidism and micropenis in non-CHH contexts to optimize developmental outcomes. Table 3 Comparative Overview of Hormonal Therapies for Micropenis and/or Undescended Testes in Infants Aspect HCG Alone HCG + FSH (or LH/FSH) Testosterone Mechanism of Action Stimulates Leydig cells → ↑ Testosterone Stimulates Leydig (via HCG) + Sertoli (via FSH) Direct androgen receptor stimulation Penile Growth Moderate (↑ in most studies) Strong (greater and more sustained) Moderate to strong (rapid response) Testicular Volume Minimal to moderate ↑ Significant ↑ with Sertoli cell maturation No consistent change World Journal of Advanced Research and Reviews, 2025, 26(02), 4220–4232 4227 Testis Descent Partial improvement Best response (up to 70–80% descent) Minimal effect Hormonal Profile ↑ Testosterone only ↑ Testosterone, LH, FSH, Inhibin B ↑ Testosterone; LH/FSH suppressed Fertility Potential Unclear; Sertoli stimulation absent Preserved via Sertoli and germ cell activation No preservation (Sertoli inactivation) Ease of Administration Easy (injections 2–3×/week) Injections or pump (more complex) Simple IM/gel application Timing Sensitivity More effective if started <6 months Best if initiated <6 months Less dependent on timing Side Effects Mild (nausea, redness, rarely gynecomastia) Mild (well tolerated in most studies) Local pain, skin irritation, behavioral shifts Literature Support Moderate (Refs 15, 19, 25, 26) Strong (Refs 12, 15, 18, 21, 23, 24, 27–29) Moderate (Refs 18, 20, 27) This comparison clearly illustrates that while all three treatments—HCG alone, HCG + FSH, and testosterone—can induce penile growth to varying degrees, only the combination of HCG + FSH replicates the full hormonal milieu of minipuberty by activating both Leydig and Sertoli cells. This dual action not only enhances penile and testicular development but also improves testicular descent and preserves future fertility potential, as evidenced by normalized inhibin B levels and sustained testicular volume gains. In contrast, testosterone monotherapy, although simple and effective in promoting rapid penile enlargement, fails to stimulate the broader hypothalamic-pituitary-gonadal axis and does not support germ cell maturation. HCG monotherapy offers a moderate middle ground, with some androgenic benefits but limited impact on Sertoli cell function. Therefore, for optimal endocrine and reproductive outcomes, HCG + FSH should be the preferred regimen, especially when treatment is initiated during the early postnatal window (<6 months). Table 4 Cochrane Risk of Bias Summary Across Key Domains (for Studies on HCG/Gonadotropin Therapy in CHH) Cochrane Domain Summary Across Studies Estimated Risk Level Randomization process Most studies were observational or small cohort trials. Randomization was rarely applied or not reported. Moderate to high risk Allocation concealment Not clearly described in the majority; likely absent due to study design (case series/single-arm studies). High risk Blinding (participants/personnel) Blinding was generally not performed due to obvious treatment effects (e.g., genital growth). High risk Blinding of outcome assessment Lab-based hormonal assays reduce detection bias; however, penile/testicular measurements may have subjective bias. Moderate risk Incomplete outcome data Most studies reported complete short-term outcome data, but long-term follow-up was lacking. Low to moderate risk Selective outcome reporting Most studies reported key hormonal and anatomical outcomes, though fertility or spontaneous puberty was omitted. Moderate risk Other biases (e.g., sample size, funding) Small sample sizes (<25 per study), non-randomized design, and single-center data reduce generalizability. Moderate to high risk The Cochrane risk of bias assessment indicates that the overall methodological quality of studies evaluating HCG/gonadotropin therapy in CHH infants is moderate to low. Most studies were observational or small cohort trials with limited use of randomization and allocation concealment, introducing potential selection bias. Blinding was often World Journal of Advanced Research and Reviews, 2025, 26(02), 4220–4232 4228 not feasible due to the visible effects of treatment, such as genital growth, further increasing performance and detection bias. While objective hormonal assays reduce some measurement bias, subjective assessment of anatomical outcomes remains a concern. Short-term data were generally complete, but long-term follow-up was lacking, and reporting of outcomes like fertility or spontaneous puberty was inconsistent. Additionally, small sample sizes and single-center designs limit the external validity of findings. Despite these limitations, the consistency of clinical and biochemical improvements across studies adds credibility to the reported benefits. Figure 5 Foster Plot of Effect Sizes and Confidence Intervals in Studies of HCG/Gonadotropin Therapy for CHH Infants The Foster plot displays effect sizes and 95% confidence intervals for 14 studies evaluating HCG/gonadotropin therapy in infants with congenital hypogonadotropic hypogonadism (CHH). Each point represents a study, with horizontal bars indicating the confidence interval range. The majority of studies cluster around the mean effect size (marked by a red dashed line), reflecting consistent and favorable treatment outcomes across different cohorts. Narrower confidence intervals in some studies suggest greater statistical precision, typically associated with larger sample sizes, while wider intervals in smaller studies reflect the expected variability. Overall, the plot supports the robustness and reproducibility of the therapeutic effect. 4. Discussion The findings of this review highlight the superior efficacy of HCG-based combination therapies, particularly those involving rFSH, in replicating the physiological and clinical outcomes of mini-puberty in infants with congenital hypogonadotropic hypogonadism (CHH). These therapies consistently achieved greater penile and testicular growth, testicular descent, and hormonal normalization compared to testosterone monotherapy. This supports the first objective of the study, which aimed to assess clinical improvements in genital development across treatment modalities. HCG + FSH regimens led to testicular descent rates as high as 70–80% and significant increases in testicular volume, which are seldom observed with testosterone alone (12, 15, 18, 21, 23). While testosterone showed some efficacy in penile lengthening (18, 20), it failed to stimulate Sertoli cell development and testicular maturation, essential for longterm reproductive potential. These findings are consistent with early work by Main et al. (11) and expanded in more recent trials by Mesas-Aróstegui et al. (21) and Ren et al. (22).