Florid rickets developed in chicks receiving doses of diphenylhydantoin
analogous to doses used in humans as anticonvulsants, vitamin D3 being
given in amounts sufficient for normal bone mineralization in controls. The
changes in the bones were directly related to the dose of diphenylhydantoin
and inversely related to the dose of vitamin D3. Bone mineralization was
assessed by roentgenography, histological examination, microradiography,
and measurement of bone ash. Of these methods, roentgenography was the
least sensitive. Rachitic changes were detectable by light microscopy and
microradiography in chicks whose skeletons appeared normal
roentgenographically. Roentgenographic evidence of rickets became
detectable only when the rickets was far advanced. Rickets developed at
serum levels of diphenylhydantoin similar to those found in patients taking
anticonvulsant medication.