Impact of parathyroidectomy timing on graft function after kidney transplantation

W.Y. van der Plas, P. von Forstner, M. El Moumni, E.Y. Koh, D.D. Dulfer, T.M. van Ginhoven, J.I. Rotmans, N.M. Appelman-Dijkstra, A. Schepers, E.J. Hoorn, J.T.H.M. Plukker, L. Vogt, A.F. Engelsman, E. Nieveen van Dijkum, S. Kruijff, R.A. Pol, M.H. de Borst

Friday 16 march 2018

14:20 - 14:30h at Willem Burger Zaal

Categories: Clinical, Session (parallel)

Parallel session: Parallel session 18: Clinical

Background

Hyperparathyroidism (HPT) is common in end-stage renal disease (ESRD). Parathyroidectomy (PTx) is the treatment of choice for ESRD patients with severe medical therapy-resistant HPT. However, whether the timing of PTx (before or after kidney transplantation, KTx) influences graft function is subject of debate, and studies addressing this subject have been underpowered. We aimed to assess the impact of PTx timing (before or after KTx) on graft function in a large multicenter cohort study.

Methods

Patients with ESRD-related HPT who underwent both PTx and KTx between 1994 – 2015 were included in a retrospective multicenter cohort study in four Dutch university medical centers. Two groups were formed and compared according to treatment sequence: PTx before KTx (PTxKTx) and PTx after KTx (KTxPTx). Primary endpoint was estimated glomerular filtration rate (eGFR, CKD-EPI) measured at 3 and 6 months and 1, 3 and 5 years after KTx in ml/min/1.73m². The correlation between the timing of PTx and KTx and the course of renal function was assessed using generalized estimating equations (GEE).

Results

The PTxKTx group consisted of 102 (55.1%) and the KTxPTx group of 83 (44.9%) patients. Recipient age, donor type (living vs. postmortal), PTx type (total vs. subtotal), and pre-KTx PTH level were significantly different between groups. Patients in the PTxKTx group received a kidney transplant after a median of 23 (interquartile range [IQR], 11 to 38) months. In the KTxPTx group, PTx followed after 30 (IQR, 15 to 74) months after KTx. An unadjusted GEE model showed that the timing of PTx was not correlated with graft function over time (mean difference -1.2 ml/min/1.73m², 95% confidence interval [CI] -8.6 to 6.2, p=0.75). The sequence of PTx in relation to KTx also did not influence the post-transplant course of eGFR over time after adjustment for center, donor and recipient age and sex, cold ischemia time, number of HLA mismatches, donor type and PTx type, pre-emptive vs. post-dialysis KTx, and PTH prior to KTx (mean difference -0.18 ml/min/1.73m², 95% CI: -16.9 to 16.6, p=0.98).

Conclusions

In this relatively large multicenter cohort study, timing of PTx, before or after KTx, does not independently impact graft function over time. Our findings support the approach to postpone PTx in patients with mildly elevated PTH levels until after KTx, given the spontaneous regression of HPT in more than half of patients after successful KTx.