Hyponatremia in geriatric inhospital patients: effects on results of a comprehensive geriatric assessment.
OBJECTIVE
To study whether geriatric patients with mild-to-moderate hyponatremia (≤131 mmol/l) reveal different outcomes in structured tests for functional and cognitive impairments, depression and malnutrition compared to normonatremic patients.


METHODS
Single-center, retrospective case control study.


METHODS
The study was conducted in a Geriatric Evaluation and Management Unit of a Department for Geriatrics and Internal Medicine.


METHODS
We included 2,880 elderly patients (75.6% female, mean age 78.6 ± 6.98 years), consecutively admitted to the GEMU primarily or from another hospital or emergency department. Results were compared between a group of 129 patients with mild-to-moderate hyponatremia (118-131 mmol/l) and an age- and sex-matched control group of 129 patients with normal serum sodium values (>135 mmol/l). To assess functional and cognitive status, depression and malnutrition we used standardized tests of a geriatric assessment.


RESULTS
16.7% (n = 477) of the total 2,880 patients were hyponatremic (≤135 mmol/l), 4.5% (n = 129) revealed moderate hyponatremia. Compared to the control group, these patients had significantly worse results in all tests of the Geriatric Assessment, including Activities of Daily Living, Mini Mental State Examination, Clock Completion Test, Geriatric Depression Score, Tinetti Mobility Test and the Timed Up&Go Test and the Mini Nutritional Assessment. Comorbidities were assessed by the Charlson Comorbidity Index and the Cumulative Illness Rating Scale with no significant difference between the two groups. The hyponatremic patients received significantly more medications than the normonatremic control group, but we could not find a significant difference with respect to the use of a distinct single drug therapy.


CONCLUSIONS
We were able to demonstrate that geriatric patients with mild-to-moderate hyponatremia revealed a significantly worse outcome in all standardized tests of the geriatric assessment compared to a normonatremic control group. Serum sodium levels should therefore be considered when interpreting common tests of geriatric assessment.
Department of Geriatrics and Internal Medicine, Hospital Hochzirl, Zirl, Austria. markus.gosch@tilak.at
Markus
M
Gosch
Birgit
B
Joosten-Gstrein
Hans-Jürgen
HJ
Heppner
Monika
M
Lechleitner
D000058:Accidental Falls / Q000517:prevention & control; D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D001317:Austria; D016022:Case-Control Studies; D003071:Cognition; D003863:Depression; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D007010:Hyponatremia / Q000209:etiology / Q000503:physiopathology* / Q000523:psychology*; D007297:Inpatients; D008297:Male; D015596:Nutrition Assessment; D012189:Retrospective Studies