Aging and Health Research (Mar 2022)
Exploring hyponatremia in older hospital in-patients: Management, association with falls, and other adverse outcomes
Abstract
Background: Hyponatremia is a common electrolyte disorder in older people. We investigated management of hyponatremia, and the association between admission hyponatremia, fall at admission, and other adverse outcomes, in older in-patients, a group less extensively studied to date. Methods: This retrospective observational study included consecutive older medical patients ≥75 years admitted over a six-week period. Primary outcome measure was fall at admission. Secondary outcomes included fractures, functional dependence/assistance to mobilize at discharge, and death. Results: Amongst 452 included patients (mean age 83.9 years), serum sodium at admission ranged from 113 mmol/L to 163 mmol/L, median 139 mmol/L (interquartile range [IQR] 136–141 mmol/L). In total, 16.7% (72/432) had hyponatremia at admission, which was mild (130-134 mmol/L) in 86%. Most (44/72) cases of hyponatremia remained uncorrected by discharge. In the hyponatraemic group, ‘routine investigations’ were variably performed- renal/liver profiles (98.9%), thyroid profiles (55.6%), serum glucose (87.5%), chest X-ray (91.7%). Other hyponatremia-specific investigations- urinary sodium and osmolarity (13.9%), serum osmolarity (15.3%) and serum cortisol (6.9%)- were not commonly checked, although osmolarity and urinary variables were assessed more frequently when sodium<130 mmol/L than if milder hyponatremia. Management appeared to be sub-optimal, with risk medications ceased infrequently and remedial treatment infrequently initiated; we did not have data regarding fluid restriction. On adjusted analyses, hyponatremia was not associated with fall at admission (aOR 0.54, 95% CI 0.24–1.22, p = 0.10) or other secondary outcomes. Conclusions: Although hyponatremia was under-investigated and sub-optimally managed, it did not appear to be associated with adverse outcomes in this cohort. Interventional trials should target the association between hyponatremia management, rectification and longer-term outcomes.
