Hypocalcemia immediately after renal transplantation.

BACKGROUND: After renal transplantation (RTX), hypercalcemia, mainly due to persistent hyperparathyroidism, and hypophosphatemia, caused by the improved ability to excrete phosphorus in the renal tubules, are expected. However, immediately after RTX, a transient reduction in serum calcium (Ca) levels has been previously reported, the reason for which is not clear.

PATIENTS AND METHODS: In 21 patients receiving ABO compatible living donor kidney transplants, serum levels of Ca, phosphorus, intact parathyroid hormone (iPTH), 1,25-dihydroxyvitamin D, and tacrolimus were measured within three wk after RTX, along with urinary Ca and phosphorus excretion. The immunosuppressive regimen consisted of a three-drug combination including a glucocorticoid, a calcineurin inhibitor, and an antimetabolite agent.

RESULTS: Serum Ca levels declined significantly during the first post-operative week. Urinary Ca excretion increased immediately after RTX and gradually normalized. Increased urinary Ca excretion did not correlate with serum levels of iPTH and tacrolimus.

CONCLUSIONS: Immediately after RTX, regardless of serum iPTH and tacrolimus levels, transient increases in urinary Ca excretion and hypocalcemia were observed. Administration of glucocorticoids is one potential cause of inappropriate urinary Ca wasting.