Diphosphonate therapy in nephrocalcinosis.

4 patients with nephrocalcinosis were treated with disodium ethane 1-hydroxy-1, 1-diphosphonate (EHDP) for a period of 13 months. No clinical side-effects were observed and growth proceeded normally. Radiographic changes of osteitis fibrosa cystica developed in 1 child and bone biopsy in 2 children showed defective osteoid mineralisation. It is suggested that EHDP prevented further crystal deposition in 3 children but did not prevent non-calcium stone formation in the 4th child. In view of this and the development of histological and radiographic evidence of osteomalacia and/or secondary hyperparathyroidism in these patients the value of EHDP remains dubious. On the other hand its use may be justified when rapidly increasing calcification is expected, as for example in hyperoxaluria.