Objective:The second generation intact parathyroid hormone (iPTH) assay is the most widely used method for the measurement of PTH which detect both full-length(1~84)PTH and(7~84)PTH. Whereas,the third generation whole PTH(wPTH)assay has been demonstrated to be specific for the measurement of(1~84)PTH with high attention from the clinic. This research was aimed to explore the features of intraoperative levels of plasma iPTH,(1~84)PTH,(7~84)PTH in chronic kidney disease complicated with secondary hyperparathyroidism(SHPT) patients with parathyroidectomy(PTX). Methods:Intraoperative levels of plasma iPTH,(1~84)PTH,(7~84)PTH in 58 severe SHPT patients who received total PTX+autotransplantation were recorded. Plasma iPTH and(1~84)PTH levels were measured by the second and third generation assays,respectively. Circulating(7~84)PTH levels were calculated by subtracting the(1~4)PTH values from the iPTH values. Results:Plasma iPTH,(1~84)PTH,(7~84)PTH levels were closely associated with each other(P < 0.001) at baseline,10 and 20 minutes after removing the last parathyroid gland. After PTX,plasma levels of iPTH,(1~84)PTH,(7~84)PTH had dropped to(19.3 ± 9.5)%,(12.7 ± 8.1)%,(26.7 ± 12.1)%,respectively at 10 minutes,(14.1 ± 5.9)%,(7.9 ± 4.4)%,(20.9 ± 8.5)% at 20 minutes respeatively. Conclusion:The third generation PTH assays were closely correlated with the second generation assays. PTX can significantly abate the levels of plasma different PTH fragments in severe SHPT patients,and intraoperative concentration of plasma(1~84)PTH was decreased more rapidly than iPTH and(7~84)PTH.