Syndrome of inappropriate antidiuretic hormone secretion and ectopic ACTH production in small cell lung carcinoma.

Background: Small cell lung carcinoma (SCLC) is frequently associated with a paraneoplastic syndrome.

Methods: We report on a rare case of SCLC presenting with syndrome of inappropriate antidiuretic hormone (SIADH) secretion and ectopic ACTH production. In accordance with the endocrine evaluation, immunohistochemical staining of the tumour was positive for ADH and ACTH. Chemotherapy with etoposide and carboplatin induced a nearly complete remission.

Conclusions: Simultaneous secretion of ADH and ACTH is infrequently reported with only five cases described in the literature. SIADH in patients with ectopic ACTH syndrome may be underdiagnosed due to the antagonistic hormone actions of cortisol and ADH on renal sodium excretion.