Disturbances in mineral metabolism after successful renal transplantation

Abnormalities of mineral metabolism remain a clinical problem after successful renal transplantation. These disturbances may be the result of derangements in divalent ion, parathyroid hormone (PTH) and/or vitamin D metabolism. We therefore measured serum Ca, phosphorus, PTH and 1,25-dihydroxyvitamin D [1,25(OH)2D] levels and fractional intestinal Ca absorption (alpha) in 6 patients before and after successful transplantation (early, less than or equal to 6 months). 3 were reexamined later (late, greater than or equal to 24 months after transplantation). The patients exhibited decreased serum levels of 1,25(OH)2D and alpha before the renal transplantation. In the early stages, renal transplantation reduced serum phosphorus from 5.55 +/- (SD)1.96 to 2.96 +/- 0.95 mg/dl (p less than 0.02); this was accompanied by a rise in serum 1,25(OH)2D from 8.7 +/- 1.5 to 26.3 +/- 8.4 pg/ml (p less than 0.005). The calcemic response to PTH infusion became normal, since the increment in serum Ca rose from 0.45 +/- 0.21 mg/dl before transplantation to 1.03 +/- 0.18 mg/dl early after transplantation. Although the mean value for alpha increase significantly from 0.263 +/- 0.048 to 0.402 +/- 0.175 (p less than 0.05), alpha was subnormal in 3 patients (alpha less than 0.37). Urinary Ca was high in 3 patients, and it exceeded absorbed Ca (from intestines) in 4 patients (indicative of negative Ca balance). Serum PTH fell significantly but remained above normal. It was hoped that late after transplantation, when patients were maintained on smaller doses of oral glucocorticoids, these abnormalities would be ameliorated. However, hypercalciuria was found in 2 of 3 patients.(ABSTRACT TRUNCATED AT 250 WORDS)