Symptoms and characteristics of individuals with profound hyponatremia: a prospective multicenter observational study

Objectives: To assess symptoms and characteristics of hyponatremia, the most common electrolyte disturbance in hospitalized individuals and a condition that is associated with substantial morbidity and mortality.

Design: Prospective observational multicenter study.

Setting: Two Swiss academic centers.

Participants: Individuals with profound hypoosmolar hyponatremia (sodium<125 mmol/L) (N=298).

Measurements: All symptoms and complete medical history including current medications, therapy management, and in-hospital outcomes were recorded.

Results: The median age of all participants was 71 (interquartile range (IQR) 60-80), 195 (65%) were female, and mean serum sodium value on admission was 120 mmol/L (IQR 116-123 mmol/L). Frequent clinical symptoms were nausea (n=130, 44%), acute vomiting (n=91, 30%), generalized weakness (n=205, 69%), fatigue (n=175, 59%), gait disturbance (n=92, 31%), recurrent falls (n=47, 16%), and acute falls (n=60, 20%). Fractures were reported in 11 participants (4%). More-severe symptoms such as acute epileptic seizures and focal neurological deficits were identified in 16 (5%) and 17 (5%) participants, respectively. The most common comorbidities were hypertension (n=199, 67%), congestive heart failure (n=44, 15%), chronic renal failure (n=64, 21%), pulmonary disease (82, 28%), and central nervous system disease (n=114, 38%). During hospitalization, 12 (4%) participants died, and 103 (35%) needed treatment in the intensive care unit.

Conclusion: A wide spectrum of symptoms accompanies profound hyponatremia. Most participants had moderate symptoms mirroring chronic hyponatremia with brain cell adaptation. Participants with profound hyponatremia had several comorbidities.