The role of quick bio-intact PTH(1-84) assay during parathyroidectomy for secondary hyperparathyroidism

The role of the quick PTH assay in surgery for secondary HPT is unclear because of overestimation of intact PTH(1-84) values due to the cross-reactivity of currently available first-generation PTH assays with non-PTH(1-84) fragments that accumulate in renal failure. In this study, we used a second-generation quick PTH immunometric assay that are claimed to detect the biologically active PTH(1-84) molecule with no cross-reactivity with PTH fragments to investigate the potential utility of the assay during parathyroidectomy for secondary HPT.

The study was performed on 18 patients (12 women, 6 men) between October 2004 and March 2005. EDTA serum samples were drawn via a peripheral venous catheter after induction of anesthesia (basal), and at 5, 10, and 30 min after excision of diseased parathyroid glands. Serum active PTH(1-84) was measured by the quick Bio-Intact PTH(1-84) assay, which is a two-site chemiluminometric assay.

At 30 min the quick Bio-PTH(1-84) level of 16 patients was under 45 pg/mL. Four parathyroid glands were removed macroscopically from 12 of the 16 patients, and three glands were removed from the other four patients. All patients were cured of their HPT. Four enlarged parathyroid glands were removed from a patient whose Bio-Intact PTH(1-84) at 30 min had not fallen below 45 pg/mL, and no other glands were found by further exploration. At the 6 mo follow-up examination, the first-generation intact PTH level of this patient was over 45 pg/mL, but several diagnostic imaging methods did not reveal any enlarged parathyroid glands. Three enlarged parathyroid glands from the other patient, and exploration led to the identification of an ectopic parathyroid gland at the carotid bifurcation.

The results of this prospective study show that quick Bio-Intact PTH(1-84) monitoring is a valuable new tool for use in the surgical treatment of secondary HPT. An intraoperative, quick Bio-Intact PTH(1-84) assay will be of value for the adequate prediction of surgical cure.