[Osteomalacia and antiepileptic drugs: study on the pathogenesis].

Severe osteomalacia with secondary hyperparathyroidism was observed in a 19-year-old mentally retarded girl, who had been treated for several years with antiepileptic drugs. Vitamin D3 orally administered in low doses led to complete reversal of all symptoms and normalization of blood chemistry, X-ray pictures demonstrated healing of all lesions. It is suggested that the alterations of vitamin-D metabolism occuring during the administration of phenobarbital and hydantion are of importance only in patients with an already lowered intake of vitamin D3 or reduced exposure to ultraviolet rays.