Timely parathyroidectomy (PTx) that avoids removal of too much parathyroid tissue may help preserve renal graft function among kidney transplant recipients with hyperparathyroidism by avoiding steep drops in intact parathyroid hormone (iPTH), according to investigators.
In a retrospective study, 48 of 892 kidney transplant recipients underwent PTx after transplantation, most commonly to relieve hypercalcemia and graft calcifications. The procedure was successful in 47 patients, with serum iPTH falling from a median of 394 to 21 pg/mL, Margret Patecki, MD, of Hannover Medical School in Germany, and colleagues reported in BMC Nephrology.
Patients had a mean estimated glomerular fitration rate (eGFR) of 60 mL/min/1.73 m2 before PTx. By 3 months after PTx, eGFR had declined significantly to 46 mL/min/1.73 m2, but held steady at 50 and 49 mL/min/1.73 m2 at 1 and 3 years, respectively. The median annual eGFR change was −0.5 mL/min/1.73 m2 before PTx and +1.0 mL/min/1.73 m2 afterward. No patient had complete recovery of renal function and none experienced graft loss within 3 years of PTx. At 15 years, graft survival and annual eGFR loss appeared comparable for kidney transplant recipients who underwent PTx and those who did not.
“Our study clearly shows that renal graft function stabilizes in patients with parathyroidectomy,” Dr Patecki and colleagues stated.
On multivariable analysis, high iPTH levels and higher eGFR before PTx predicted eGFR loss after PTx. The eGFR before surgery and the iPTH decrease after surgery predicted lower graft function at 12 months after PTx.
The average eGFR loss was 14 mL/min/1.73 m2. Consequently, PTx can be considered safe only in patients with an eGFR greater than 30 mL/min/1.73 m2, Dr Patecki’s team reported. Otherwise, they noted, expected eGFR after PTx will be in the range of stage 5 chronic kidney disease.
Timely PTx and precise resection appear crucial in preserving renal function, they noted. Surgery should be performed before iPTH spikes too high to avoid the loss of eGFR that occurs as a result of a steep drop in iPTH afterward. To prevent below normal iPTH levels and hypocalcemia after surgery, it is important to avoid removal of too much parathyroid tissue. Intraoperative iPTH monitoring may help in this regard, according to the authors.
In this study, PTx consisted of subtotal resection in 14 cases, total resection with autotransplantation in 28 cases, and total resection without autotransplantation in 4 cases (2 cases had missing information). One third of patients required calcium supplementation at 1 year after PTx and three-quarters were treated with vitamin D. Hyperparathyroidism recurred in 5 patients. One patient required 2 PTx procedures.
Current guidelines do not give specific recommendations regarding target iPTH values following parathyroidectomy, timing of the procedure after kidney transplantation, and the extent of parathyroid tissue removal, the authors noted.
Patecki M, Scheffner I, Haller H, Gwinner W. Long-term renal graft outcome after parathyroidectomy – a retrospective single centre study [published online February 18, 2020]. BMC Nephrol 21:53. doi: 10.1186/s12882-020-01723-x