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eBook details
- Title: Unexpected Serum Parathyroid Hormone Profiles in Some Patients with Primary Hyperparathyroidism (Technical Briefs)
- Author : Clinical Chemistry
- Release Date : January 01, 2006
- Genre: Chemistry,Books,Science & Nature,
- Pages : * pages
- Size : 189 KB
Description
Second-generation parathyroid hormone (PTH) assays, also termed intact PTH assays, measure not only PTH(184) but also a PTH fragment that resembles PTH(7-84) (1). To date, 2 new commercial third-generation assays have been developed: the Cyclase Activating PTH IRMA (Scantibodies Laboratory, Inc.) and the Nichols Advantage[R] chemiluminescent Bio-Intact PTH assay (Nichols Institute Diagnostics). These assays do not cross-react with N-terminally truncated PTH fragments, including PTH(7-84) (2,3). In accordance with these observations, PTH concentrations were lower when measured with third-generation than with second-generation assays in healthy individuals (4-6), in patients with primary hyperparathyroidism (PHPT) (4, 6, 7), and in dialysis patients (8). However, 2 recent reports described PTH concentrations that were higher when measured with third- than with second-generation assays in 3 patients with parathyroid carcinoma (9) and in 1 patient with severe PHPT (10). In this report, we present a similar PTH profile in 7 women with PHPT [group 1; mean (SD) age, 57.2 (13.5) years; range, 37-74 years] whose PTH concentrations were evaluated simultaneously with both thirdand second-generation PTH assays. These patients were from a group of 145 consecutive PHPT patients [28 men and 117 women; mean age, 61.7 (13.2) years], living in Paris and its suburbs (4), who underwent surgery in our Endocrine Surgery Department during a 10-month period. A group of 74 healthy persons (14 men and 60 women) from the same area [age, 62.2 (4.6) years] served as the control group for determination of the reference interval for each PTH assay tested. All of the control individuals had a serum 25-hydroxyvitamin D (25-OHD) concentration 50 nmol/L. This investigation was approved by the local ethics committee and was conducted in accordance with the guidelines published in the Helsinki Declaration. Informed consent was obtained from all participants. Blood samples were collected after an overnight fast, just before the patients entered the operating room, and after surgery. Samples were centrifuged at 4[degrees]C, and serum aliquots were promptly frozen at -80'C. The length of this procedure never exceeded 2 h because the stability of PTH measured with the third-generation assays is shorter than that measured with second-generation assays (2,5). We used standard methods to measure calcium, phosphate, albumin, and creatinine and RIA (DiaSorin) to measure serum 25-OHD concentrations in PHPT patients and in the control group. Serum PTH was measured with 4 different assays, based on 2-site immunometric methods: the Duo PTH IRMA (Scantibodies Laboratory, Inc.), which includes 2 different assays-the total intact and the cyclase-activating PTH assays; and 2 immunochemiluminometric assays from Nichols Institute Diagnostics, the Nichols Advantage[R] chemiluminescent intact and biointact PTH assays. The total intact PTH (T-iPTH) and intact PTH (iPTH) assays are second-generation assays, whereas the cyclase-activating PTH (CA-PTH) and Bio-Intact PTH (Bio-iPTH) assays are third-generation assays. Briefly, both second- and thirdgeneration PTH assays use purified goat polyclonal antibodies. Two types of antibodies were used. Capture antibodies, common in both generations of assays, were directed against the PTH(39-84) region and differed in their interaction with the solid phase: antibodies immobilized on polystyrene-coated beads (Scantibodies) or biotinylated antibodies reacting with streptavidin-coated particles (Nichols). Detection antibodies, specific to each generation, were directed either against the PTH(1-34) region in second-generation assays, or against the PTH(1-6) region in third-generation assays. These antibodies were labeled with either iodine (Scantibodies) or acridinium ester (Nichols). In each case, assays were run according to the manufacturer's protocol, and analytical characteristics for these PTH assays have been reported previously (2, 5, 6,11).
 "Unexpected Serum Parathyroid Hormone Profiles in Some Patients with Primary Hyperparathyroidism (Technical Briefs)" by Clinical Chemistry # Book PDF Kindle ePub Free){kind=link}