BALTIMORE – Performing a parathyroidectomy in kidney transplant patients before their transplant can reduce the risk of graft failure and provide other benefits, the findings of a retrospective study of 913 patients suggest.
Uremic hyperparathyroidism (UHPT) is common in patients with end-stage kidney disease, and elevated parathyroid hormone (PTH) levels have been linked with delayed graft function after kidney transplants, but current guidelines for PTH levels may not go far enough to reduce the risk of graft failure and other post–kidney transplant complications in people with elevated PTH before transplant, according to Dr. Glenda G. Callender of Yale University, New Haven, Conn., and her colleagues.
Dr. Glenda G. Callender
“Uremic hyperparathyroidism was associated with an increased risk of complications in the first year post kidney transplant,” Dr. Callender said at the annual meeting of the American Association of Endocrine Surgeons. “Pre–kidney transplant parathyroidectomy was associated with a decreased risk of post–kidney transplant graft failure. This implies that pre–kidney transplant reduction of PTH levels should be considered in patients with UPHT.”
The Yale researchers reviewed outcomes of 913 patients at their institution who had a kidney transplant from 2005 to 2014. They analyzed biochemical values before kidney transplant and at three intervals post transplant: at 1 month, 6 months, and 1 year. Among the outcomes they evaluated were calcium and PTH levels, estimated glomerular filtration rate, complications, delayed graft function, and graft failure. The overall graft survival rate was 97.8% 1 year after kidney transplantation.
Overall, 49.4% of patients (451) had a diagnosis with UHPT before kidney transplant; 6.2% of all patients (57) had parathyroidectomy before kidney transplant and another 2% (18) had parathyroidectomy at some point after their kidney transplant operations. Median baseline PTH levels were higher in the UHPT patients: 206 pg/mL vs. 159 pg/mL for the non-UHPT group, Dr. Callender reported.
The researchers captured complete data on 37 of the 57 patients who had pretransplant parathyroidectomy. Twenty-four (65% of the group) had subtotal parathyroidectomy in which 3.5 glands were removed, and 12 (32%) had fewer than 3.5 glands removed. One patient had total parathyroidectomy, she said.
Among the patients with UHPT, the median pre–kidney transplant PTH was similar between the pretransplant parathyroidectomy and the no-parathyroidectomy groups: 218 pg/mL and 180 pg/mL, respectively, Dr. Callender said.
Pre–kidney transplant diagnosis of UHPT had an odds ratio of 1.44 for complications in the first year after transplant surgery, but not necessarily a greater risk for graft function or graft failure, she said. However, those relative risks changed with the degree of PTH above normal. Patients with UHPT who had pretransplant parathyroidectomy had a lower risk of graft failure, with an odds ratio of 0.547.
Current Kidney Disease Improving Global Outcomes (KDIGO) guidelines recommend maintaining PTH levels in patients with UHPT before they have kidney transplant surgery at no more than nine times normal. To test the optimal PTH levels before kidney transplant, the researchers analyzed thresholds ranging from two to nine times the normal limit.
“A pre–kidney transplant [PTH] level greater than or equal to six times normal was associated with post-transplant graft failure but not with delayed graft function or complications in the first year post kidney transplant,” Dr. Callender said. “Although the thresholds at two and four times normal were statistically significant, there was a continued risk significant for graft failure above six times normal.”
This finding “suggests that perhaps the current KDIGO guideline of maintaining patient PTH at up to nine times normal is too liberal,” Dr. Callender said.
She acknowledged several limitations of the study: its retrospective nature, small sample size, and “many missing data points” because a wide variety of dialysis centers with varying documentation standards collected information.
“However,” Dr. Callender said, “we believe these findings support the design and implementation of a multi-institutional, prospective, randomized control trial to evaluate whether a change in management of patients with uremic hyperparathyroidism is warranted.”
Dr. Callender and her coauthors had no financial relationships to disclose.