Evolution of PTH assays.
PTH metabolism is complex and the circulating forms include the intact 1-84 molecule as well as several carboxyl-terminal fragments. The first generation of PTH assays included several types of competitive assays, with specificities that spanned carboxyl, mid-region and amino-terminal portions of the molecule. The limitations of these assays and the methodological evolution led to the description of 2nd generation non-competitive immunometric assays for PTH in the late 80's, based on the recognition of the PTH molecule by two different antibodies, one directed against de amino-terminal and other against the carboxyl-terminal segments. The observation that in some circumstances "long" carboxyl-terminal segments were also measured by 2nd generation assays led to the development of 3rd generation assays based on amino-terminal specific antibodies that are specific for the first amino acids, measuring only the molecular forms that activate PTH1R. The practical and cost-benefit advantages of these assays are still debatable. The recent observation that carboxyl-terminal fragments of PTH have biological activity via a distinct receptor than PTH1R, points to the future need of more than one assay in order to evaluate parathyroid hormone function.
Vieira
José Gilberto H
JG
Laboratorio Fleury, São Paulo, SP, Brasil. jose.vieira@fleury.com.br
Kunii
Ilda
I
Nishida
Sônia
S
D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000276:immunology*; D000918:Antibody Specificity; D001681:Biological Assay; D002118:Calcium / Q000097:blood; D006801:Humans; D006961:Hyperparathyroidism / Q000175:diagnosis* / Q000276:immunology; D010281:Parathyroid Hormone / Q000032:analysis / Q000737:chemistry / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology*; D011863:Radioimmunoassay; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000276:immunology* / Q000378:metabolism
D000911:Antibodies, Monoclonal; C470125:PTH protein, human; C473449:PTH1R protein, human; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D044168:Receptor, Parathyroid Hormone, Type 1; D002118:Calcium