Acute Severe Euvolemic Hyponatremia Caused by Segmental Pulmonary Thromboembolism and Complicated by COVID-19 Infection: A Case Report

Hyponatremia is frequently encountered in clinical practice. Euvolemic hyponatremia (syndrome of inadequate antidiuresis, SIAD) represents diagnostic and management challenges regarding etiology unraveling, gradual acute substitution, and later causal treatment. Here we present a case of severe SIAD caused by segmental pulmonary thromboembolism and manifested as acute psychosis. COVID-19 complicated the course of the disease acquired in hospital settings. By simultaneous treatment of pulmonary thromboembolism, gradual substitution of hyponatremia, and treatment of COVID-19, the patient completely recovered biochemically and mentally. Even experienced clinicians are confused about diverse clinical manifestation of SIAD. Attentive correction of hyponatremia and treatment of its etiology are the mainstays of SIAD management.