Hypophosphatemia and Reyeʼs syndrome

Hypophosphatemia may occur in Reye's syndrome. We retrospectively studied 42 patients with Reye's syndrome to determine the frequency and degree of hypophosphatemia, to identify possible causes, and to determine whether hypophosphatemia was related to the severity of disease or mortality. Nineteen (46%) patients were hypophosphatemic at the time of hospital admission. Five of these had a serum phosphorus level less than 2.5 mg/dl and three were 1.5 mg/dl or less. During the subsequent hospital course, 32 (78%) patients developed hypophosphatemia. It was of moderate degree (2.5 mg/dl or less) in 20 patients, and was severe (1.5 mg/dl or less) in eight patients. Hypophosphatemia correlated with concurrent hyperglycemia but not with other potential causes studied. The degree of hypophosphatemia during treatment roughly paralleled the severity of illness but was not a predictor of outcome. The need for treatment of hypophosphatemia in Reye's syndrome has not been established, and hypocalcemia as a complication of excess phosphate infusion should be avoided.