RICKETS ASSOCIATED WITH ANTICONVULSANT MEDICATION

Abstract

An example of rickets associated with anticonvulsant medication is described with onset at the age of 5 years 9 months. This patient had received anticonvulsant therapy since the age of 5 months. X-rays and serum values were normal up to age 3 years 2 months. Diagnosis of rickets at age 5 years 9 months was made by decreased serum calcium and phosphorus and elevated alkaline phosphatase plus characteristic x-ray findings. Other causes of rickets were excluded. Healing occurred with oral vitamin D: 10,000 units daily for two weeks, then 2,500 units daily for four weeks. Return of calcium and phosphorus to normal and early x-ray healing had occurred in six weeks. In six months complete healing by x-ray had occurred. Alkaline phosphatase level was persistently elevated, with both bone and liver fractions increased, but finally returned to normal when 50,000 units of oral vitamin D were given daily for 30 days. A plausible mechanism appears to be increased catabolism of vitamin D due to induction of hepatic microsomal enzymes when anticonvulsant medication is given.