Mineralization defect but no effect on hypercalcemia during clodronate treatment in secondary hyperparathyroidism

In four patients with severe secondary hyperparathyroidism, treatment with clodronate caused no decrease in serum calcium. In one of the patients treatment for seven months was associated with a severe mineralization defect which was not caused by aluminium. This lesion was reversible upon termination of clodronate treatment. In a single patient without hyperparathyroidism, a precipitous decrease in serum calcium was observed due to clodronate. However, long-term treatment with clodronate did not ameliorate ectopic calcification in this patient. It is concluded that in severe secondary hyperparathyroidism, clodronate does not always decrease serum calcium. Our experience suggest that clodronate like other bisphosphonates may inhibit bone mineralization.