Sodium abnormalities are present in more than half of adult patients upon admission to a hospital for COVID-19, with hyponatremia being more prevalent than hypernatremia, a recent study shows.

Moderate/severe hypernatremia is associated with an increased risk for in-hospital mortality, and both hyponatremia and hypernatremia are associated with an increased hospital length of stay, according to investigators.

The study, by Jamie S. Hirsch, MD, of the Donald and Barbara Zucker School of Medicine at Hofstra/Northwell in Great Neck, New York, and colleagues, studied 9946 patients aged 18 years or older admitted with COVID-19 across 13 hospitals in the metropolitan New York region. Of these, 3532 (35.5%) had mild hyponatremia, 904 (9.1%) had moderate/severe hyponatremia, 319 (3.2%) had mild hypernatremia, and 383 (3.8%) had moderate/severe hypernatremia, the investigators reported online in Nephrology Dialysis Transplantation.

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The proportion of patients who experienced in-hospital mortality was highest for those with moderate or severe hypernatremia (60.6%), followed by mild hypernatremia (51.1%), moderate/severe hyponatremia (28.9%), mild hyponatremia (23.2%), and normonatremia (22.6%).

Compared with the patients who had normonatremia, those with moderate/severe hyponatremia had significant 26% increased odds of in-hospital mortality after adjusting for demographics, comorbid conditions, and illness severity. The association did not persist after correcting for glucose levels. Patients with moderate/severe hypernatremia had significant 2-fold increased odds of in-hospital mortality, an association that persisted after correcting for glucose levels.

Among survivors, the median length of stay varied by sodium category: 5.8, 6.4, 8.8, 7.1, and 8.8 days for patients with normonatremia, mild hyponatremia, moderate/severe hyponatremia, mild hypernatremia, and moderate/severe hypernatremia, respectively.

Patients with either hyponatremia or hypernatremia were more likely to have hospitals stays of at least 7 days compared with patients who had normal sodium levels.

The investigators defined normonatremia as a serum sodium level (in mEq/L) of 136-144; mild and moderate/severe hyponatremia as levels of 130-135 and less than 130, respectively, and mild and moderate/severe hypernatremia as levels of 145-149 and 150 or higher, respectively.

Dr Hirsch and colleagues acknowledged that their study was limited by its retrospective and observational design. “Thus, the results only reflect the association of dysnatremias with in-hospital death in COVID-19, but do not infer causal relationship.”


Hirsch JS, Uppal NN, Sharma P, et al. Prevalence and outcomes of hyponatremia and hypernatremia in patients hospitalized with COVID-19. Published online March 16, 2021. Nephrol Dial Transplant. doi:10.1093/ndt/gfab067