Serum alkaline phosphatase and urinary hydroxyproline values in children receiving phenobarbital with and without vitamin D.

Concentrations of serum alkaline phosphatase and total urinary hydroxyproline were measured in 36 children to study the effect of phenobarbital administration with respect to the development of rickets in patients receiving anticonvulsive medications over prolonged periods of time. Administration of phenobarbital led to the appearance of increased AP and HOP values very early in the course of treatment and without any obvious bone changes suggestive of rickets; a single large oral dose of vitamin D had no appreciable effects in restoring the biochemical derangement. On the other hand, the administration of vitamin D in a daily dose of 4,000 IU for a period of two months hampered the appearance, or restored already existing changes of latent rickets, in children receiving anticonvulsive medication. The results in the present study favor the concept that phenobarbital administration is implicated in the development of rickets. The need for simultaneous daily administration of supplements of vitamin D in subjects receiving anticonvulsive drugs is stressed.