Syndrome of Inappropriate Secretion of Antidiuretic Hormone Found by Preoperative Electrolyte Analysis

Abstract

To the Editor A 73-year-old woman, scheduled for extraction of 9 teeth under general anesthesia, had a serum sodium concentration of 137 mEq · L−1 at another hospital 3 weeks earlier. Preoperative blood analysis revealed a serum sodium concentration of 124 mEq · L−1, serum osmolality 260 mOsm · L−1, urinary sodium concentration 48 mEq · L−1 with a urinary osmolality of 822 mOsm · L−1, and serum arginine vasopressin concentration of 1.4 pg · mL−1 (normal range, 0.3–3.5 pg · mL−1). Thyroid and adrenal functions were normal. History included dementia, cerebral infarction, cerebellar atrophy, osteoporosis, lumbar and pelvic fractures, and chronic lymphocytic leukemia with anemia, and she had been bedridden in a hospital for several years. The medication history from the previous hospital disclosed that tablets of combined sulfamethoxazole and trimethoprim (Bactramin®) had been added because of the oral infection and a diagnosis of syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with these drugs was suspected.1,2 Discontinuing these drugs, additional salt intake, fluid restriction, and infusion of hypertonic saline (3% NaCl) increased serum sodium concentration to 136 mEq · L−1 by the day before surgery.3,4 General anesthesia and surgery were uneventful and 6 days later, the patient was discharged from our hospital. The patient consented to publication of this report. Diagnosing SIADH based on clinical findings is difficult because of the lack of signs of excessive volume of extracellular fluid.2 In this case, SIADH was identified by chance based on preoperative electrolyte analysis. Drug-induced SIADH can occur with administration of vincristine, tricyclic antidepressants, opioids, antipsychotic drugs, carbamazepine, and selective serotonin reuptake inhibitors.2 To our knowledge, however, no reports have described SIADH induced by sulfamethoxazole and trimethoprim. If preoperative examination shows that hyponatremia is present preoperatively, additional measurements of serum osmolality, urinary sodium concentration, urinary osmolality, and serum arginine vasopressin level are warranted to clarify whether this finding is associated with SIADH. Kazuna Sugiyama, DDS, PhD Atsushi Kohjitani, DDS, PhD Yoko Iwase, DDS, PhD Yozo Manabe, DDS, PhD Department of Dental Anesthesiology Kagoshima University Graduate School of Medical and Dental Sciences Kagoshima, Japan [email protected]