Effects of Demeclocycline in an Elderly Patient with Syndrome of Inappropriate Secretion of Antidiuretic Hormone（SIADH）

Antidiuretic hormone（ADH） secretion is abnormal or alters serum osmolality inpatients with syndrome of inappropriate secretion of antidiuretic hormone （SIADH）,of which the causes and treatment remain undetermined. We treated SIADH using a classical approach followed by demethylchlortetracycline（demeclocycline）. A 75–year–old hypertensive, diabetic man sustained a brain contusion. Computed tomography showed a skull fracture and subarachnoid hemorrhage, and MRI revealed a cystic pituitary tumor. Blood findings indicated traumatic syndrome of inappropriate secretion of antidiuretic hormone（SIADH）. Saline infusion and NaCl intake returned Na and Cl levels to near normal. However, the patient’s clinical status deteriorated with increasing ADH concentrations. Sodium levels were corrected with diuretics and fluid replacement. Antihypertensive, antiarrhythmic, gastrointestinal drugs were administered along with demeclocycline（450 mg/day） and drinking water was restricted. C–reactive protein（CRP）levels remained low（0.02 mg/dL） under this regime and demeclocycline was tapered to 150mg/day. The patient resumed premorbid activities after about four months and continued treatment as an outpatient. The most recent Na, Cl and K values were normal （137, 102 and 4.7 mEq/L respectively）. Demeclocycline prevents infections of the central nervous system by promoting antidiuretic hormone（ADH） secretion and reducing urine output; it also has antidiuretic action. However, the causes and treatment of this condition remain largely unknown and neither clinical trials nor double–blind controlled studies have assessed the actual mechanism（s） of demeclocycline action. Thus, the effects of demeclocycline remain questionable. We plan to investigate more effective agents against SIADH.