Significance of monitoring Bio-Intact PTH (1-84) during parathyroidectomy for secondary hyperparathyroidism.

Background: The Bio-Intact PTH (1-84) assay has recently been developed to specifically measure the intact PTH (1-84) molecule, and in this study we used it to investigate sequential changes in serum Bio-Intact PTH (1-84) levels during parathyroidectomy for secondary HPT.

Material And Methods: The subjects of this study were 70 patients (41 women, 29 men) who underwent parathyroidectomy between April 2002 and March 2005. Ethylene diamine tetraacetic acid serum samples were drawn via a peripheral venous catheter after induction of anesthesia (basal), and at 5, 10, and 30 min after diseased glands excision. Serum active PTH (1-84) was measured by the Bio-Intact PTH (1-84) assay, which is a two-site chemiluminometric assay.

Results: When 4 or more diseased parathyroid glands were removed, the basal of Bio-Intact PTH (1-84) level in patients without persistent HPT (52 cases) was 539 +/- 355 pg/mL. The level of the Bio-Intact PTH (1-84) at 30 min after sufficient parathyroidectomy had decreased to less than 45 pg/mL, whereas the Bio-Intact PTH (1-84) level in patients with persistent HPT at 30 min was greater than 45 pg/mL (3 cases). After removal of three or fewer diseased parathyroid glands (15 cases), the Bio-Intact PTH (1-84) at 30 min in patients without persistent HPT (13 cases) was less than 45 pg/mL. The 2 patients whose the Bio-Intact PTH (1-84) at 30 min was greater than 45 pg/mL underwent reoperation, and residual enlarged parathyroid gland in the neck was removed.

Conclusions: The Bio-Intact PTH (1-84) level at 30 min after parathyroidectomy seems to be useful for judging whether the parathyroidectomy is complete irrespective of the number of glands removed from patients with secondary HPT. When only three diseased parathyroid glands are removed, the surgeon can decide whether to continue or stop neck exploration according to the level of Bio-Intact PTH (1-84) at 30 min.