Three Synchronous Tumors Discovered in SIADH Investigation

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) is a common cause of euvolemic hyponatremia which has many possible etiologies such as tumors (mainly lung cancers). We present a case of a 79-year old women hospitalized due to microcytic anemia with transfusion need and hyponatremia due to SIADH. Three primary tumors without known metastasis were discovered. The case shows the importance of studying causes of hyponatremia. LEARNING POINTS: Hyponatremia is a common electrolytic disorder during hospitalization and is associated with greater mortality. Correction of hyponatremia, cause can be devastating unless the underlying causes are investigated as it can be caused by severe diseases. Cancer must be excluded in the absence of an obvious etiology of SIADH (drugs, pulmonary and nervous system disorders).