Chronic hyponatremia: a new risk factor for fragility fractures in the elderly?

ÓRgÃO O ICIAL DA SOCIEDADE PORTUgUESA DE REUMATOLOgIA 308 CARTA AO EDITOR Ch onic hypona emia: a new isk ac o o agili y ac u es in he elde ly? ACTA REUMATOL PORT. 2015;40:308-309 To he Edi o , Mul iple isk ac o s o os eopo o ic ac u e, inclu - ding os eopo osis and alls, a e widely known. I is also clea ha os eopo o ic ac u es impose a signi ican mo bidi y and mo ali y in he elde ly, wi h majo mone a y cos s associa ed. Recen s udies sugges ha ch onic hypona emia (se um [Na+] < 135mEq/L), albei sligh (se um [Na+] = 125-134 mEq/L), may be associa ed wi h alls, os- eopo osis and ac u es. PubMed sea ch o “(“os eo- po osis” OR “ ac u e” OR “ alls”) AND “hypona e - mia”“ (Ma ch 1s 2014, las i e yea s, english) e ie ed h ee dozen esul s. Se e al s udies ha e shown associa ions be ween ch onic hypona emia and alls, ac u es o os eo- po osis: • Falls incidence in elde ly people wi h mild ch onic hypona emia is signi ican 1 • Hypona emia is no associa ed wi h lowe bone mine al densi y1(despi e he ela ion be ween hy- pona emia and os eopo osis sugges ed by a p e i- ous c oss-sec ional su ey2) • Hypona emia incidence in elde ly pa ien s admi ed o ac u e seconda y o acciden al all is conside a - ble3 • Hypona emia is e y p e alen in elde ly pa ien s wi h agili y ac u e.4 Bu , can hypona emia pe se cause bone disease? In- deed, se e al s udies ha e shown ha ch onic hy- pona emia may be an independen isk ac o o alls, ac u es and os eopo osis due o inc eased p obabili- y o alls1[adjus ed odds a io (aOR) 1.35], os eo- po osis2[aOR 2.85 o hip os eopo osis], ac u e3[OR 4.16] and os eopo o ic ac u e5[OR 1.46], and he in- c eased isk o inciden non e eb al ac u e1[adjus - ed haza d a io (aHR) 1.34 95% CI 1.08-1.68, Hen iques M1 1. Medical Depa men , Physical and Rehabili a ion Medicine Depa men , Na y’s Physical Educa ion Cen e; No h Lisbon Hospi al Cen e – Sain Ma y’s Hospi al p=0.009] and e eb al ac u e1(combined p e alen and inciden ) [aOR 1.61, 95% CI 1.00-2.59, p=0.049]. Fu he mo e, ch onic hypona emia is associa ed wi h inc eased likelihood o in-hospi al dea h a e hip ac- u e (OR 3.64)6and inc eased all-cause mo ali y isk (aHR 1.21, 95% CI 1.03-1.43, p=0.022)1. Labo a o y s udies indica e ha hypona emia s imu la es os eoclas ogenesis7and animal model s u - dies associa e hypona emia wi h dec eased hickness o co ical bone and inc eased numbe o os eoclas s2. The e a e al eady p oposals o he mechanism o bone disease induced by ch onic hypona emia in humans (Figu e 1)8. This ques ion seems o be p oblema ic conside ing ha ch onic hypona emia is a common diso de in he elde ly8and usually asymp oma ic (75-80% o cases7): 7.2% o pa ien s a ending o he i s ime in p ima y ca e o 49.2% o hose obse ed o he i s ime in he hospi al9, 10% o pa ien s admi ed o he eme gency oom (ER),10 7% o ambula o y elde ly up o 53% o ins i u ionalized elde ly2. Mo eo e , he elde ly a e subjec o si ua ions o g ea e p opensi y o ch onic hypona emia ins alla- ion, as polypha macy (e.g. diu e ics, an idep essan s, an iepilep ics, p o on pump inhibi o s) and diseases (e.g. synd ome o inapp op ia e sec e ion o an idi- u e ic ho mone (± 50% o ch onic hypona emia ca - ses), diabe es melli us, hypo hy oidism, hepa ic ci - hosis, conges i e hea ailu e, kidney disease)8. Physicians who ollow elde ly pa ien s should be awa e o he associa ion be ween bone disease and ch o nic hypona emia. As he measu emen o se um sodium is a simple, a ailable and inexpensi e p oce- du e, i should be achie ed in elde ly pa ien s wi h in- c eased isk o hypona emia, p esen ing clinical symp- oms consis en wi h hypona aemia, o which a e ob- se ed in he ER o bone inju y8. Upon he hypona emia diagnosis i ’s necessa y o es ablish he app op ia e ea men . In he asymp o - ma ic cases i ’s ecommended, a leas , he iden i ica ion ÓRgÃO O ICIAL DA SOCIEDADE PORTUgUESA DE REUMATOLOgIA 309 Hen iques M o e e sible causes o p e en ecu ence and luid es - ic ion o 0.5 o 1L/day. Selec i e asop essin ece p o V2 an agonis s may be a ea men op ion in he u- u e. Bene i s o p e en ion, diagnosis and e ec i e ea - men o ch onic hypona emia in alls, os eopo osis and ac u e isk, as quali y o li e, a e ye o p o e8. Fo his, new p ospec i e s udies a e needed. Ch onic hypona emia may p esen i sel as a new and impo an independen isk ac o o alls, ac u - es and os eopo osis in he elde ly. Tha said, medical communi y should be ale o his p oblem and in es in p e en ion, diagnosis and ea men ! CoRREspondEnCE o Moisés Hen iques Es ada da Luz nº199, 6º D o 1600-155 Lisboa, Po ugal E-mail: [email p o ec ed] REFEREnCEs 1. Hoo n EJ, Ri adenei a F, an Meu s JB, e al. Mild hypona e- mia as a isk ac o o ac u es: he Ro e dam S udy. J Bone Mine Res. 2011;26(8):1822-1828. 2. Ve balis JG, Ba sony J, Sugimu a Y, e al. Hypona emia-indu- ced os eopo osis. J Bone Mine Res. 2010;25(3):554-563. 3. Kengne FG, And es C, Sa a L, e al. Mild hypona emia and isk o ac u e in he ambula o y elde ly. Q J Med. 2008; 101:583-588. 4. Cumming K, Hoyle GE, Hu chison JD, Soiza RL. P e alence, in- cidence and e iology o hypona emia in elde ly pa ien s wi h agili y ac u es. PLoS One. 2014;9(2):e88272. 5. A ampa zis S, Gae cke LM, Funk GC, e al. Diu e ic-induced hypona emia and os eopo o ic ac u es in pa ien s admi ed o he eme gency depa men . Ma u i as. 2013;75(1):81-86. 6. Hagino T, Ochiai S, Wa anabe Y, e al. Hypona emia a ad- mission is associa ed wi h in-hospi al dea h in pa ien s wi h hip ac u e. A ch O hop T auma Su g. 2013;133(4):507-511. 7. Ba sony J, Sugimu a Y, Ve balis JG. Os eoclas esponse o low ex acellula sodium and he mechanism o hypona emia-in- duced bone loss. J Biol Chem. 2011;286(12):10864-10875. 8. Ayus JC, Neg i AL, Kalan a -Zadeh K, Mo i z ML. Is ch onic hypona emia a no el isk ac o o hip ac u e in he elde - ly? Neph ol Dial T ansplan . 2012;27(10):3725-3731. 9. Hawkins RC. Age and gende as isk ac o s o hypona emia and hype na emia. Clin Chim Ac a. 2003;337(1-2):169-172. 10. A ampa zis S, F auchige B, Fiedle GM, e al. Cha ac e is ics, symp oms, and ou come o se e e dysna emias p esen on hos pi al admission. Am J Med. 2012;125(11):1125.e1-1125. e7. In e io limi o se um [Na+] o impai ed gai (134mEq/L) and educed a en ion (132mEq/L) 1/3 o o al body Na+ is in he bones; 40% o bone [Na+] is exchangeable o blood ci cula ion ↓ gai balance + ↓ a en ion + men al con usion ↓ bone mine aliza ion + ↑ os eoclas s ac i i y CNS impai men Os eopo osis Falls Bone agili y Ch onic Hipona emia Bone ac u e In e io limi o se um [Na+] o impai ed gai (134mEq/L) and educed a en ion (132mEq/L) 1/3 o o al body Na+ is in he bones; 40% o bone [Na+] is exchangeable o blood ci cula ion ↓ gai balance + ↓ a en ion + men al con usion ↓ bone mine aliza ion + ↑ os eoclas s ac i i y CNS impai men Os eopo osis Falls Bone agili y Ch onic Hipona emia Bone ac u e FIGURE 1. Mechanism o bone disease induced by ch onic hypona emia in humans