Clinical utility of an immunoradiometric assay for parathyroid hormone (1-84) in XXXX .

@entity1 @entity459 @entity1472 @entity460 @entity3243 @entity652 @entity461
The reliable diagnosis of @entity459 depends on the measurement of @entity461 . The @entity461 assays in widespread use measure not only the hormone but also hormone fragments, thus limiting the clinical utility of the assays. A new immunoradiometric assay (IRMA) using an antigenic determinant at the extreme @entity1472 -terminal of the @entity461 molecule detects only full-length @entity461 (1-84). We compared three @entity461 assays and determined the presence of @entity461 (1-84) and @entity461 fragments in serum and @entity3243 of @entity1 with @entity459 . We studied 56 @entity1 with @entity459 . @entity461 levels were increased in 63% using the midmolecule RIA; in 73% in the "intact" IRMA; and in 96% in the @entity461 (1-84)-IRMA. The @entity461 (1-84)-IRMA correlated with the other assays (midmolecule RIA R = +0.736; P < 0.0001; "intact"-IRMA R = +0.951; P < 0.0001) and indices of disease activity (serum @entity460 R = +0.511, P < 0.0001; alkaline phosphatase R = +0.489, P = 0.001; and radius bone density R = -0.366, P < 0.01). In 21 consecutive @entity1 undergoing parathyroidectomy, 18 had @entity3243 . Intact @entity461 was higher than @entity461 (1-84)-IRMA in both serum and glandular homogenates from these @entity1 . Similar proportions of @entity461 (1-84) and hormone fragments were found in both @entity652 [66 +/- 3% of "intact" @entity461 -reflected @entity461 (1-84) and sera (73 +/- 2% of "intact" @entity461 reflected @entity461 (1-84)]. We conclude that the @entity461 (1-84)-IRMA offers improved diagnostic sensitivity in @entity1 with @entity459 than other currently available assays. This study also provides evidence that both @entity461 (1-84) and @entity461 fragments are produced in @entity3243 and that peripheral metabolism of hormone and fragment does not alter the proportion of bioactive hormone.
