Recurrent renal salt wasting in a child treated with carboplatin and etoposide

Background. Nephrotoxicity of carboplatin is rare, especially in children with normal renal function. A 3-year-old boy had localized esthesioneuroblastoma and received 2 courses of carboplatin (200 mg/m2/day during a 1-hour infusion for 3 consecutive days) associated with etoposide (150 mg/m2/day after carboplatin). Because of a good tumor response, a second course was given 21 days later. Complete surgical excision and local irradiation were performed. However, the tumor recurred a few months later, and the patient subsequently died of the disease. Methods. Renal function initially was assessed by standard baseline chemistry and technetium-panetetic acid (Tc-DTPA) clearance. Follow-up included ionic controls and tubular exploration during the episodes of hyponatremia. Results. Hyponatremia occurred 4 days after completion of the first course and resolved after intravenous supplementation. It recurred 20 days after the second course despite salt and magnesium prehydration and posthydration and resolved 17 days later. No glomerular dysfunction was noticed. The association of urinary bicarbonate loss with elevated N-acetyl-β-glucosaminidase suggested a proximal tubular damage. Conclusions. Standard doses of carboplatin may lead to recurrent renal salt wasting in children with initially normal renal function.