|A Quantitative Mass Spectrometry-Based Assay for the Clinical Analysis of Parathyroid Hormone and Its Heterogeneous Oxidized and Truncated Post Translational Modifications|
: 145 : 2016.04.01 16:32
|일시 : 2016.03.30 17:00|
|소속 : University of Melbourne|
|발표자 : Gavin E. Reid|
|장소 : R404|
Parathyroid hormone (PTH) plays a critical role in the regulation of circulating blood calcium levels, and serves as a biomarker of secondary hyperparathyroidism associated with the diagnosis of disorders such as vitamin D deficiency or chronic kidney disease (CKD), and for monitoring the effectiveness of treatment e.g., hemodialysis. Immuno-chemiluminescent assays for full length (i.e., 1-84) PTH have historically been problematic due to variable standardization, cross reactivity with truncated PTH fragments (e.g., 7-84), and variable correlations with biological parameters. A recent report that PTH may be oxidized in vivo further complicates these issues, since oxidized PTH is biologically inactive.
To overcome these challenges, I will describe in this presentation the development and application of an alternate strategy for analysis of a series of clinical hemodialysis patient plasma samples, involving immunoaffinity enrichment, liquid chromatography–tandem mass spectrometry (LC-MS/MS), and a novel dual isotope-labeled internal standard quantitation approach to (i) quantitatively determine the nature of circulating full length and truncated PTH and their individual oxidized isoforms, (ii) differentiate between in vivo and ex vivo oxidative modifications, and (iii) evaluate the effects of PTH oxidation on current immunochemiluminescent PTH assays.