Cefdinir Induced Syndrome of Inappropriate Release of Antidiuretic Hormone

Abstract

Antidiuretic hormone (ADH) is secreted by the posterior pituitary gland. Unsuppressed release of ADH leads to hyponatremia. This condition is referred to as syndrome of inappropriate antidiuretic hormone secretion (SIADH). Here we present the first case report of cefdinir-induced SIADH. A 76 year-old male was prescribed cefdinir for a urinary tract infection. Two days later he fell and sustained a fracture of C1, his sodium was notably 128 mmol/L. Seven days later he presented again to the emergency room with generalized weakness, headaches, and decreased appetite and was found to have a sodium level of 116 mmol/L. Serum osmolality was appropriately decreased at 243 mOsmol/kg, urine osmolality was not maximally dilute at 422 mOsmol/kg, and urine sodium was 94 mmol/L. On presentation, cefdinir was held and he received ceftriaxone for the first 48 hours of his admission, after which this was also stopped. He was treated with urea powder and received one dose of tolvaptan with progressive improvement in sodium levels allowing for discharge. On post exposure day 27 serum sodium level normalized (142 mmol/L), without the need for urea powder and all symptoms resolved. This is the first reported case of SIADH associated with cefdinir though there have been scant case reports [1] of cephalosporins causing SIADH