Severe hyponatremia due to trimethoprim-sulfamethoxazole-induced SIADH.

Hyponatremia, a serum sodium level of <135 mEq/L, is the most common electrolyte abnormality occurring in 5%-35% of hospitalized patients. It is a predictor of increased morbidity and mortality. Diuretics, psychotropic, and antiepileptic drugs are commonly implicated in drug-induced hyponatremia. Trimethoprim-sulfamethoxazole and spironolactone are two commonly prescribed drugs; unfortunately, most providers are unfamiliar with these two drugs causing hyponatremia. Simultaneous use of trimethoprim-sulfamethoxazole and spironolactone can cause serious drug interactions that increase the risk of hyponatremia, hyperkalemia, and overall mortality. Despite recommendations to avoid using these two drugs concurrently, many healthcare providers continue to prescribe them together. We report a case of an elderly female with severe hyponatremia caused by trimethoprim-sulfamethoxazole superimposed on a chronic but stable mild hyponatremia.

Unusual presentation of a small cell lung cancer with bilateral breast metastases: Case report and a brief review of the literature.

Small cell lung cancer (SCLC) is a smoker's disease and occurs almost exclusively in smokers. SCLC is a high-grade neuroendocrine tumor and commonly presents as a central tumor with bulky mediastinal adenopathy. It is notorious for causing widespread disease and paraneoplastic syndromes. The usual sites of metastasis include the liver, brain, bone, and adrenals. SCLC presenting with breast metastasis is unusual; however, there are reports of unilateral and bilateral breast metastases. SCLC with bilateral breast metastases is extremely rare, with only five previously reported cases available in the literature. We are taking this opportunity to report and add to the growing literature on the unusual presentation of a small cell lung cancer with bilateral breast metastases.