DISTURBANCES IN MINERAL METABOLISM AFTER SUCCESSFUL RENAL-TRANSPLANTATION

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  • 1 January 1985
    • journal article
    • research article
    • Vol. 11  (3) , 167-172
Abstract
Abnormalities of mineral metabolism remain a clinical problem after successful renal transplantation. These disturbances may be the result of derangements in divalent Fe, parathyroid hormone (PTH) and/or vitamin D metabolism. Serum Ca, phosphorus, PTH and 1,25-dihydroxyvitamin D [1,25(OH)2D] levels and fractional intestinal Ca absorption (.alpha.) were measured in 6 patients before and after successful transplantation (early, .ltoreq. 6 mo.). There were reexamined later (late, .gtoreq. 24 mo. 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 P from 5.55 .+-. (SD) 1.96 to 2.96 .+-. 0.95 mg/dl (P < 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 < 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. increased significantly from 0.263 .+-. 0.048 to 0.402 .+-. 0.175 (P < 0.05), .alpha. was subnormal in 3 patients (.alpha. < 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. Hypercalciuria was found in 2 of 3 patients. Serum PTH remained elevated in all 3 patients despite adequate creatinine clearance. Fasting hypercalciuria (> 0.1 mg/100 ml glomerular filtration) was encountered in 2 of 3 patients. Apparently parathyroid stimulation, hypercalciuria and subnormal intestinal Ca absorption may persist in some patients after successful renal transplantation in the face of a rise in serum 1,25(OH)2D and improved skeletal responsiveness to PTH. The exact cause of these disturbances remains to be elucidated.