Fluid Replacement Versus Fluid Restriction in COVID-19 Associated Hyponatremia

Hyponatremia is one of the most frequently observed electrolyte abnormalities in coronavirus disease 2019 (COVID-19). Literature describes syndrome of inappropriate anti diuretic hormone (SIADH) as the mechanism of hyponatremia in COVID-19 requiring fluid restriction for management. However, it is important to rule out other etiologies of hyponatremia in such cases keeping in mind the effect of an alternate etiology on patient management and outcome. We present a case of hypovolemic hyponatremia in a patient with COVID-19, which unlike SIADH, required fluid replacement early in the disease course for its correction. A 52-year-old Filipino gentleman presented with a three-week history of diarrhea and symptomatic hyponatremia. There was no history of fever or respiratory symptoms. Physical examination revealed a dehydrated and confused middle-aged gentleman. Labs revealed lymphopenia, thrombocytopenia, and severe hyponatremia (108 mmol/L). Blood cultures and stool workup were negative. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nasopharyngeal swab was positive. Hyponatremia workup excluded SIADH. The patient had hypovolemic hyponatremia due to gastrointestinal (GI) losses and was managed with saline infusion for correction of hyponatremia with improvement in his clinical status. Hyponatremia in COVID-19 is not only secondary to SIADH but can also be due to other etiologies. Hypovolemic hyponatremia should be distinguished from SIADH as these conditions employ different management strategies, and early diagnosis and management of hypovolemic hyponatremia affects morbidity and mortality.