Diffuse calcinosis and intradermal tophi in a uremic pateint: effect of low-calcium hemodialysis and mechanism of hypercalcemia.

Soft tissue calcification is a frequent complication in end-stage renal disease (ESRD) patients with a high serum calcium-phosphate product, but systemic involvement of both the visceral organs and skin is rarely seen. We report on a newly diagnosed ESRD patient with gouty nephropathy who had initial presentations of extensive intradermal tophi, diffuse calcinosis, and hypercalcemia. He received maintenance hemodialysis (HD) with low-calcium dialysate (1.25 mEq/l) for 11 months. Although the above complications diminished, serum calcium remained elevated. Thereafter, unexpected cervical lymphadenitis from a Mycobacterium tuberculosis (TB) infection with high extra-renal production of calcitriol was found. Serum calcium levels normalized only after anti-TB treatment for 2 months. We thought that this patient might have had occult TB infection before the start of HD, which resulted in calcitriol production and hypercalcemia. In addition, concomitant hyperphosphatemia in chronic renal failure contributed to severe diffuse calcinosis. After the initiation of HD therapy, both the elevated serum calcitriol levels and accelerated resolution and mobilization of diffuse calcinosis from low-calcium HD contributed to persistent hypercalcemia.