Phosphate depletion therapy in two ectopic calcification syndromes.

Ectopic calcification may be a complication of a wide variety of pathologic conditions. Subcutaneous calcification frequently results in restriction of motion at joints in addition to cosmetic deformity. Parenchymal tissue calcification may result in decreased organ function. Dietary phosphate restriction and total body phosphate depletion with aluminum containing antacids were used in an attempt to decrease the deposition of subcutaneous calcium phosphate which occurs with two separate syndromes. Two subjects with hyperphosphatemic tumoral calcinosis were studied by metabolic balance, by long-term clinical evaluation, and routine laboratory and radiographic techniques before and after 1 year of phosphate depletion. One patient with a newly described syndrome--normocalcemic, hypercalciuric, subcutaneous calcification--was similarly studied. The etiology of this disorder is unknown. No consistent clinically significant evidence of regression of the lesions was noted in either syndrome, although one patient with tumoral calcinosis did demonstrate some regression of his lesions. It is not clear if this response failure was due to the intrinsic nature of the diseases or to failure of patient compliance secondary to a relatively unpalatable diet.