Syndrome of inappropriate antidiuresis (SIAD) in a patient with rectal carcinoma undergoing preoperative radiation.

摘要

We report a first case of the syndrome of inappropriate antidiuretic hormone secretion occurring following preop-erative radiation for rectal carcinoma. The syndrome of inappropriate antidiuretic hormone secretion (SIADH) consists of hyponatremia, inappropriately elevated urine osmo-lality (>200 mOsm/kg), excessive urinary sodium excretion (>30 mEq/L) and decreased serum osmolality. SIADH is a known paraneoplastic syndrome, which may result from numerous types of cancer, including small cell lung cancer, gastrointestinal cancer and lymphoma. Small cell lung carcinoma alone accounts for 75% of all cases of SIAD caused directly by tumours. It has also been known to occur as a complication of chemotherapy use, including vinca alkaloids or cyclophosphamide. It has been described only once before in conjunction with rectal carcinoma.