Early history of familial hypophosphataemic vitamin D-resistant rickets. Report of three cases observed since birth.

Three patients with familial hypophosphataemic vitamin D-resistant rickets (FHR) born to affected mothers have been clinically, radiologically and biochemically observed since birth. The value of the different early diagnostic signs is evaluated, and the efficiency of early phosphate and vitamin D treatment is discussed. Our observations suggest the following conclusions: Infants of FHR affected mothers can be diagnosed as having the disease by careful physical examinations and by a pathological increase of serum alkaline phosphatase with normal serum calcium, before radiological signs of rickets occur. The serum phosphate concentrations in early infancy are variable and of little or no diagnostic help. Early treatment is useful to cure or even to avoid rickets and to normalize serum alkaline phosphatase, but not hypophosphataemia. In spite of some favorable results, the influence of early started treatment on growth and leg deformities is difficult to assess due to the variations of individual expressivity of the disease.