Evolution of hyperparathyroidism after renal transplantation in children - Effect of pre-emptive transplantation and duration of dialysis

Background. The main causes of secondary hyperparathyroidism in end-stage renal disease are supposed to disappear after renal transplantation thanks to good graft function, but the regression of the glandular hyperfunction often takes a long time. The aim of the present work was to evaluate the possible role of the duration of dialysis in the outcome of parathyroid function after renal transplantation in children. Methods and results. The study was based on data from calcium-phosphate metabolism before and over a 90-day period after renal transplantation in 41 children. Patients were divided into: group I, pre-emptive transplantation (n = 17), and group II, dialysis prior to transplant (n = 24). Groups were matched for age, sex, causes of chronic renal failure, duration of ischaemia time and immunosuppressive treatment. No significant difference was noted with respect to all assessments of serum Ca, P, 25OHD and Mg between the two groups. On the other hand, PTH was statistically different both before and after renal transplantation, while glomerular filtration rate and tubular function tests were identical. Conclusion. It is therefore suggested that children submitted to pre-emptive transplantation achieve normal PTH levels sooner than dialysed children, which might denote an 'inappropriate PTH secretion' in the latter group. Skeletal resistance to PTH, low density of calcitriol receptor in parathyroid and/or nodular rather than diffuse hyperplasia of the gland could be speculated to explain such conclusions.