Fractional intestinal calcium absorption in epileptics on anticonvulsant therapy. Short-term effect of 1,25-dihydroxycholecalciferol and 25-hydroxycholecalciferol.

Fractional intestinal 47Ca calcium absorption (alpha) in 12 epileptic outpatients receiving chronic high-dose anticonvulsant therapy was reduced (p less than 0.05) compared to 12 matched normal controls. Six of the epileptics were treated orally with 0.5 microgram of 1,25-dihydroxycholecalciferol (1,25-DHCC) per day and six with 10 microgram of 25-hydroxycholecalciferol (25-HCC) per day for 10 days. The alpha was determined before and after treatment and compared with the effect of 0.5 microgram of 1,25-DHCC per day given for 10 days to 6 controls. An increase of the same order in alpha was found in all groups (p less than 0.05). No changes were observed in the serum levels of calcium, phosphorus, alkaline phosphatase or iPTH during treatment. Urinary calcium excretion was low in the epileptic patients and rose during treatment. The investigation demonstrates that the sensitivity of the intestine to 1,25-DHCC is normal in epileptic patients on anticonvulsant therapy and that 1,25-DHCC and 25-HCC in the given doses had an equal effect on the reduced intestinal calcium absorption.