MSIA-SRM assay for parathyroid hormone and vitamin D binding protein: correlation with clinical immunoassay methods and application to clinical samples

Contact: David Taylor Dept. of Clinical Biochemistry King’s College Hospital London SE5 9RS davidtaylor8@nhs.net We have developed multiplexed, high-throughput, quantitative and precise SRM assays for both PTH and VDBP. The MSIA-SRM approach allows rapid and automated enrichment to achieve high sensitivity (ng/L) and selectivity. Simultaneous monitoring of intact and variant PTH species allows the precise quantification of active and inactive forms. Correlation of the PTH MSIA-SRM assay using only the N-terminal peptide (aa 1-13) with the traditional immunoassay confirms that commercial immunoassays overestimate the amount of active PTH. Further, no evidence for PTH(7-84) was found in the data set. Further work will validate the utility of VDBP measurement in the routine assessment of vitamin D status. !"#$"%"&#'(')&