[Early diagnosis and early treatment of hypophosphatemic vitamin D-resistant rickets].

This is a report on two children with hypophosphatemic vitamin D-resistant rickets born to affected mothers diagnosed at the age of one and three months, respectively. The most important diagnostic criterium is the reduced value of the transport maximum of phosphorus in relation to glomerular filtration rate. At the age of one and six months, respectively, therapy with 1.25 (OH)2D3 and phosphate was started with the result of normal growth of length, radiological healing of rickets and normalisation of alkaline serum-phosphatase, but persistently low fasting values of serum-phosphorus during the time of observation up to twelve and twenty-four months of age, respectively in both children. The therapy with 1.25 (OH)2D3 and phosphate has a positive effect on intestinal absorption of phosphorus, because the serum-phosphorus is significantly elevated to the age corrected normal range two hours after oral administration of phosphate. There were no negative effects during therapy. It seems, therefore, that early diagnosis and therapy with 1.25 (OH)2D3 and phosphate is successful in healing this rare form of rickets.