Impact of Resolution of Hyponatremia on Neurocognitive and Motor Performance in Geriatric Patients

This observational study investigated the impact of hyponatremia resolution on the results of a comprehensive geriatric assessment (CGA) in 150 patients with age >= 70 years and serum sodium <130 mEq/L. The test battery including Barthel index of Activities of Daily Living (ADL) and various tests of neurocognitive function, motor performance and mood stability was applied on admission and at discharge. Changes of individual test results (Delta) were analyzed and normonatremic patients matched for age, gender, and ADL served as reference group. Most CGA test results improved. The improvement was more pronounced in the hyponatremia group with respect to ADL (Delta ADL: 14.3 +/- 17.1 vs. 9.8 +/- 14.7; p = 0.002) and MMSE (Delta MMSE: 1.8 +/- 3.0 vs. 0.7 +/- 1.9; p = 0.002). Effect sizes were small (i.e., >0.2) in the overall analysis for Delta ADL and Delta MMSE and moderate (i.e., >0.5) for Delta MMSE in the euvolemic subgroup. Beneficial effects on Delta ADL and Delta MMSE were only observed in the subgroup of patients in which [Na+] was raised by >5 mEq/L and multivariable linear regression analysis confirmed [Na+] increase to be an independent predictor of MMSE improvement. Resolution of hyponatremia has a beneficial impact on the geriatric patients' overall functional status, in particular in euvolemic cases.