Long-term renal graft outcome after parathyroidectomy - a retrospective single centre study

Abstract

Background: Surgical correction of hyperparathyroidism after kidney transplantation has been associated with significant graft function decline. We examined the effects of parathyroidectomy on short- and long-term graft function and its potential predictors.

Methods: For this retrospective, monocentric study we identified 48 (5.5%) out of 892 patients from our protocol biopsy program who received renal transplantation between 2000 and 2007, with parathyroidectomy after transplantation. Data from up to three years after parathyroidectomy was collected and analyzed with multivariable linear regression analyses.

Results: Main indications for parathyroidectomy were hypercalcemia and graft calcifications. Parathyroidectomy was successful in 47 patients, with a median drop in serum intact parathormone (iPTH) from 394 to 21 pg/ml. Mean estimated glomerular fitration rate (eGFR) before parathyroidectomy was 60 ± 26 ml/min. At three months after parathyroidectomy, the eGFR was 46 ± 18 ml/min (p < 0.001) but remained stable at one and three years (50 ± 20; 49 ± 20 ml/min). The median annual eGFR change was - 0.5 ml/min before and + 1.0 ml/min after parathyroidectomy. Multivariable modeling identified high iPTH levels and higher eGFR before parathyroidectomy as predictors of the eGFR drop after parathyroidectomy. Lower graft function twelve months after parathyroidectomy was predicted by the eGFR before and the iPTH drop after surgery.

Conclusions: These results indicate that the extent of parathyroidectomy is critical and too much lowering of iPTH should be avoided by timely parathyroidectomy, before reaching extreme high iPTH values. In view of the observed loss of eGFR, parathyroidectomy can be considered safe in patients with an eGFR above 30 ml/min.

Keywords: Hypercalcemia; Hyperparathyroidism; Kidney function; Parathyroidectomy; Renal transplantation.

Fig. 1

Intact parathormone levels before and after parathyroidectomy. Blue lines represent individual values; the red line represents the median course of all patients. iPTH; intact parathormone

Fig. 2

Serum calcium before and after parathyroidectomy. Green lines represent individual values; the red line represents the mean

Fig. 3

Correlation between parathormone levels and serum calcium before and after parathyroidectomy. Note different scales for iPTH values pre- and post-parathyroidectomy. iPTH; intact parathormone

Fig. 4

eGFR before and up to 3 years after parathyroidectomy. Black lines represent individual eGFR values, the red line the mean eGFR. eGFR estimated glomerular filtration rate