Third- or second-generation parathyroid hormone assays: a remaining debate in the diagnosis of primary hyperparathyroidism.
BACKGROUND
Since the demonstration that the second-generation PTH assays, also called intact PTH assays, recognize a non-1-84 PTH fragment in addition to the intact 1-84 PTH, new PTH assays defined as third-generation assays have been commercialized. Two previous studies aimed at evaluating whether these third-generation PTH assays improved the diagnostic sensitivity for primary hyperparathyroidism (PHPT), but they yielded opposite results.


METHODS
In the present study we compared two second-generation PTH assays (the total intact PTH assay from Scantibodies Laboratory, Inc., and the intact PTH assay from Nichols Institute Diagnostics) with two third-generation assays (the cyclase-activating PTH assay also from Scantibodies Laboratory and the bio-intact PTH assay from Nichols Institute) in a series of 145 consecutive PHPT patients operated in our endocrine surgery department over a 10-month period. A group of 74 healthy subjects served as controls.


RESULTS
The diagnostic sensitivities for PHPT of the total intact, the intact, the cyclase-activating, and the bio-intact assays were 93.8%, 97.3%, 84.2%, and 89.0%, respectively, with 95% confidence intervals in the control groups of 10-46, 11-60, 8.4-34, and 9-41 ng/liter, respectively.


CONCLUSIONS
Our findings demonstrate that the diagnostic sensitivities of second- and third-generation PTH assays are similar. Third-generation PTH assays do not therefore improve the diagnosis of elevated serum PTH levels in PHPT, although there are numerical differences among the values.
Boudou
Philippe
P
Department of Hormonal Biology, Saint-Louis University Hospital, Assistance Publique-Hôpitaux de Paris, 1 avenue Claude Vellefaux, 75475 Paris Cedex 10, France. philippe.boudou@sls.aphp.fr
Ibrahim
Fidaa
F
Cormier
Catherine
C
Chabas
Almécinda
A
Sarfati
Emile
E
Souberbielle
Jean-Claude
JC
D000368:Aged; D004704:Endocrinology / Q000379:methods*; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood / Q000175:diagnosis*; D007158:Immunologic Techniques / Q000592:standards; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000031:analogs & derivatives* / Q000097:blood; D012680:Sensitivity and Specificity
C470125:PTH protein, human; D010281:Parathyroid Hormone