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

Abstract

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 (Δ) 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 (ΔADL: 14.3 ± 17.1 vs. 9.8 ± 14.7; p = 0.002) and MMSE (ΔMMSE: 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 ΔADL and ΔMMSE and moderate (i.e., >0.5) for ΔMMSE in the euvolemic subgroup. Beneficial effects on ΔADL and ΔMMSE 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.

Serum Sodium in Relation to Various Domains of Cognitive Function in the Elderly US Population

“…In this study, cognitive impairment was de ned as a modi ed Mini-Mental Status score less than 84 or a Trail Making Test Part B time greater than 233 seconds (9). In addition, a study conducted in 150 patients aged 70 years and older from the University Hospital Cologne, showed that resolution of hyponatremia (< 130 mmol/L) by > 5 mmol/L was signi cantly associated with an increase in MMSE scores (ΔMMSE: 1.8 ± 3.0 vs. 0.7 ± 1.9; p = 0.002) (23). Reversibility has also been reported in previous animal studies mentioned below (24,25).…”

Mild hyponatremia is associated with low skeletal muscle mass, physical function impairment, and depressive mood in the elderly

“…In clinical practice, it is particularly important to know that the elderly with mild hyponatremia have low physical function because, as mentioned above, mild hyponatremia often goes unnoticed by patients and physicians and physicians are often hesitant to treat asymptomatic mild hyponatremia with SNa ≥130 mEq/L. However, a previous study reported a significant improvement in activities of daily living and cognition among geriatric patients effectively treated for hyponatremia [ 27 ]. Mild hyponatremia in the elderly deserves more of our attention.…”

Serum sodium in relation to various domains of cognitive function in the elderly US population

“…In this study, cognitive impairment was defined as a modified Mini-Mental Status score less than 84 or a Trail Making Test Part B time greater than 233 s [ 9 ]. In addition, a study conducted in 150 patients aged 70 years and older from the University Hospital Cologne, showed that resolution of hyponatremia (< 130 mmol/L) by > 5 mmol/L was significantly associated with an increase in MMSE scores (ΔMMSE: 1.8 ± 3.0 vs. 0.7 ± 1.9; p = 0.002) [ 24 ]. Reversibility has also been reported in previous animal studies mentioned below [ 25 , 26 ].…”