Resorption of soft tissue calcification: a possible mechanism of hypercalcemia

In rats with intact parathyroid glands and normal renal function, extraskeletal Ca3(PO4)2 deposits cause an increase in serum Ca2+ concentration from 4.39 +/- 0.07 to 5.24 +/- 0.13 mEq/l (p less than 0.001) and an increase in urinary excretion of calcium. In rats with acute renal failure and secondary hyperparathyroidism, Ca3(PO4)2 deposits potentiate the pre-existing elevation of serum calcium from 4.9 +/- 0.08 to 5.4 +/- 0.13 mEq/1 (p less than 0.01). In parathyroidectomized rats, Ca3(PO4)2 produce a significant increase in serum calcium from 3.39 +/- 0.07 to 4.19 +/- 0.2 mEq/1 (p less than 0.005). Induction of acute renal failure elevated the serum calcium concentration both in intact rats from 4.39 +/- 0.07 to 4.9 +/- 0.08 mEq/1 (p less than 0.01) and in parathyroidectomized rats from 3.39 +/- 0.07 to 3.85 +/- 0.15 mEq/1 (p less than 0.02). In parathyroidectomized rats with acute renal failure, Ca3(PO4)2 deposits cause an increase in serum Ca2+ concentration from 3.85 +/- 0.15 to 4.26 +/- 0.15 mEq/1 (p less than 0.05).