Renal transplant and secondary hyperparathyroidism

Abstract

Objective. To investigate the impact of mineral metabolism, renal function, months on dialysis and months since transplant for predicting intact parathyroid hormone (iPTH) levels in a cohort of patients who had undergone their first renal graft with estimated glomerular filtration rates (eGFRs) of 30–60 and >60 ml/min/1.73 m². Material and methods. One hundred and twenty-eight patients (mean age 56.0±14.6 years) with an eGFR of >30 ml/min/1.73 m² were included. The median time since transplant was 88.6 months (range 2.8–403.2 months). Blood samples were collected for measurement of iPTH, 25-hydroxyvitamin D₃, 1,25-dihydroxyvitamin D₃, calcium, albumin, phosphate and creatinine. The eGFR was calculated using the formula for the modification of diet in renal disease. Results. One hundred and three patients (80%) had an elevated level of iPTH, 29 (23%) had hypercalcaemia and 42 (35%) had a 25-hydroxyvitamin D₃ level of <40 nmol/l. In stepwise backward regression, eGFR and 25-hydroxyvitamin D₃ were associated with iPTH, as follows: iPTH =24.91−(0.06×25-hydroxyvitamin D₃)−(0.16×eGFR) (R²=0.14). No associations with these two variables were, however, detected in patients with an eGFR of >60 ml/min/1.73 m². Forty patients (31%) were transplanted pre-emptively, and the iPTH concentrations were significantly lower in these patients. Conclusions. Decreasing eGFR was the single most important variable predicting iPTH level in a cohort of renal transplant patients with an eGFR of 30–60 ml/min/1.73 m², but not in patients with an eGFR of >60 ml/min/1.73 m². Patients transplanted pre-emptively had a statistically significantly lower iPTH level compared with patients who had received dialysis.

• Renal transplantation
• secondary hyperparathyroidism
• vitamin D