Intra-operative monitoring of parathyroid hormone (ioPTH) by a low-cost central laboratory second generation assay accurately predicts disease persistence in patients undergoing surgery for secondary hyperparathyroidism (SHPT), according to a new Italian study.
Carlo Vulpio, MD, and colleagues from Catholic University of the Sacred Heart in Rome, reviewed ioPTH decay in 42 hemodialysis patients undergoing parathyroidectomy (PTx) at their institution from 2007 to 2014. All patients had PTH levels above 800 pg/mL with hypercalcemia and/or hyperphosphoremia refractory to medical treatment. Fifteen patients underwent subtotal PTx and 27 total PTx, all without autotransplantation. Five samples were taken for ioPTH monitoring, including during pre-intubation, post-manipulation of parathyroid glands, and at 10, 20, and 30 minutes after gland excision.
No difference in ioPTH decline was observed between patients having subtotal or total PTx, according to results published online in Clinical Biochemistry. As such, ioPTH will not help select patients who need immediate or delayed parathyroid autotransplantation.
Combining absolute and percentage ioPTH decay at 30 minutes after excision of the parathyroid glands was highly accurate in predicting persistent SHPT (i.e., 100% sensitivity, 92% specificity, 100% negative predictive value, and 93% accuracy). Persistent SHPT was defined as PTH levels above 65 pg/mL at 1 week, 6 months, and 12 months after surgery.
According to the researchers, ioPTH monitoring using a central laboratory parathyroid hormone assay “is useful and accurate to define whether PTx is complete, irrespective of the number of glands removed and the type of PTx performed.” Gauging surgical success, however, would still require consensus on factors such as timing and thresholds. In this study, ioPTH concentrations of 166 pg/mL and above and percentage greater than 12% remaining at 30 minutes after excision predicted persistent SHPT.
Conflicting results have been reported with ioPTH. Previous research has found that intact and whole parathyroid hormone assays predicted surgical failure similarly.