Endocrine Abstracts

Context: Hyponatremia is a hormonal disorder of water metabolism encountered in 2% of community dwelling adults in America and in over 15-20% of hospitalized adults.^1,2 Hyponatremia leads to increase in risk of falls, cognitive deficits, gait disturbances, loss of independence, prolongation of hospital stay and mortality among older patients admitted to hospitals.³

Objective: To determine in-hospital mortality among older patients admitted to the hospital with concomitant hyponatremia and to assess length of hospital stay and degree of independence at discharge from hospital

Methods: This was an observational cohort recruited from the medical and allied wards of a tertiary care teaching hospital in India. Older patients (≥60 years) with documented hyponatremia (Serum Sodium < 135 mEq/l) who provided informed consent were included. Patients with suspected pseudohyponatremia and those with functional impairments prior to hospitalization were excluded. A similar number of age and gender matched older patients without hyponatremia during hospital stay were recruited as a control group. Demographic and clinical data was noted from the patients’ records. Primary outcome measured was in-hospital mortality. Other outcomes included length of hospital stay (LOHS) and loss of independence recorded on the day of discharge by assessment of Katz index of independence (KII) in daily living.⁴ A lower score indicates loss of independence.

Results: Hundred and twenty-five patients with hyponatremia and an equal number of controls were consented. Mean age (68.8±7.7 vs.68.2±6.5 years P-value=0.8) and male gender (57.6% vs.56.8% P-value=0.8) were comparable and mean serum sodium were 127.1±5.5 vs 137.9±2.5 mEq/l respectively among cases vs. controls (P-value<0.0001). In-hospital mortality was higher among patients with hyponatremia (20(16%) vs. 11(8.8%), P-value=0.08) but not statistically significant. LOHS was longer (8.4±5.7 vs. 5.0±2.8 days, P-value<0.0001) and KII scores were lower (3.9±1.9 vs. 4.8±1.5, P-value=0.0003) among cases. Severe functional impairment at discharge (KII <2) was significantly higher among cases (29.5% vs. 13.1%, P-value=0.006). Significant positive correlation was seen between serum sodium and KII scores (correlation coefficient -0.28, P value=0.003) suggesting increasing loss of independence at discharge with lower sodium values.

Conclsions: Older patients with hyponatremia during hospitalization were less likely to survive the hospital stay and spend longer time in hospital. Loss of independence was significantly associated with both presence of hyponatremia and co-related with the severity of hyponatremia.

References: 1. J Appl Lab Med. 2021;6(1):63-78.

2. Am J Med. 2006;119(7 Suppl 1): S30-S35.

3. QJM. 2009;102(3):175-182.

4. JAGS, 31(12), 721-726