Mineral metabolism in European children living with a renal transplant: a European society for paediatric nephrology/european renal association-European dialysis and transplant association registry study

Abstract

Background and objectives: Data on mineral metabolism in pediatric renal transplant recipients largely arise from small single-center studies. In adult patients, abnormal mineral levels are related to a higher risk of graft failure. This study used data from the European Society for Paediatric Nephrology/European Renal Association-European Dialysis and Transplant Association Registry to study the prevalence and potential determinants of mineral abnormalities, as well as the predictive value of a disturbed mineral level on graft survival in a large cohort of European pediatric renal transplant recipients.

Design, setting, participants, & measurements: This study included 1237 children (0-17 years) from 10 European countries, who had serum calcium, phosphorus, and parathyroid hormone measurements from 2000 onward. Abnormalities of mineral metabolism were defined according to European guidelines on prevention and treatment of renal osteodystrophy in children on chronic renal failure.

Results: Abnormal serum phosphorus levels were observed in 25% (14% hypophosphatemia and 11% hyperphosphatemia), altered serum calcium in 30% (19% hypocalcemia, 11% hypercalcemia), and hyperparathyroidism in 41% of the patients. A longer time since transplantation was associated with a lower risk of having mineral levels above target range. Serum phosphorus levels were inversely associated with eGFR, and levels above the recommended targets were associated with a higher risk of graft failure independently of eGFR.

Conclusions: Abnormalities in mineral metabolism are common after pediatric renal transplantation in Europe and are associated with graft dysfunction.

Keywords: calcium; epidemiology and outcomes; hyperphosphatemia; pediatric kidney transplantation; transplant outcomes.

Figure 1.

Distribution of patients with calcium, phosphorus, and PTH levels according to target levels stratified by age, post-transplant period, and eGFR. The asterisk indicates that the number of patients was too small. PTH, parathyroid hormone.

Figure 2.

Mineral levels according to eGFR. Data represent levels of calcium SD score (A), phosphorus SD score (B), and PTH (C) with 95% confidence intervals. Adjustments were made for age, sex, time since transplantation, and year of transplantation. PTH, parathyroid hormone.