[Differential diagnostic problems resulting from massive doses of vitamin D and suspected pituitary dwarfism in the father of a child with vitamin-D-resistant rachitis (author's transl)].

A 1.8-year-old female child with retarded statomotor development and growth was reported. Radiologically and chemically, a rachitis was found which clearly improved following administration of 600,000 U. vitamin D3. Examination of the father who was thought to be suffering from pituitary dwarfism revealed hypophosphatemia and radiologic signs of osteomalacia. The diagnosis of a hypophosphatemic vitamin-D-resistant rachitis in this child could only be established with certainty during the course of the following months.