Hyponatremia due to adrenal insufficiency and the syndrome of inappropriate antidiuretic hormone secretion: clinical cases

Hyponatremia is defined as a serum sodium concentration below 135 mEq/L. It is one of the most common electrolyte imbalances, potentially leading to significant morbidity and even mortality. Early recognition is crucial to prevent severe complications; however, clinical diagnosis is often challenging due to the nonspecific nature of symptoms. In most cases, hyponatremia results from water retention, which dilutes sodium concentration in the extracellular fluid and plasma. One key factor to consider in the diagnostic process is cortisol deficiency, which can contribute to the development of this condition. The primary causes of hyponatremia include adrenal insufficiency and the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Adrenal insufficiency disrupts sodium homeostasis due to a deficiency in glucocorticoids and mineralocorticoids, leading to sodium loss and hypovolemia. The condition may develop due to autoimmune processes, infections, or as a consequence of adrenal surgery. Meanwhile, SIADH is characterized by excessive secretion of antidiuretic hormone, causing water retention and hypotonic hyponatremia. This syndrome can result from malignancies, central nervous system disorders, pulmonary diseases, or the use of certain medications. Hyponatremia presents with a broad spectrum of clinical manifestations, ranging from mild fatigue and nausea to severe neurological impairment, including seizures and coma. The severity of symptoms often correlates with both the degree and the rate of sodium decline. In this publication, we present two clinical cases of symptomatic hyponatremia: one caused by adrenal insufficiency and the other associated with SIADH. We analyze diagnostic approaches, including laboratory tests and imaging studies, as well as therapeutic strategies aimed at addressing the underlying causes. Treatment modalities range from fluid management and hormone replacement therapy to pharmacological interventions, depending on the etiology and severity of the condition. Recognizing the underlying cause of hyponatremia is essential for effective management and improving patient outcomes.