A sensitive radioimmunoassay using a monoclonal antibody that is equipotent for ercalcitriol and calcitriol (1,25-dihydroxy vitamin D2 and D3)

E. Barbara Mawer, Jacqueline L. Berry, J. Paul Cundall, Pamela E. Still, Anne White

    Research output: Contribution to journalArticlepeer-review

    Abstract

    A monoclonal antibody has been used in a sensitive radioimmunoassay that measures 1, 25-dihydroxyvitamin D2 (ercalcitriol) and 1, 25-dihydroxyvitamin D3 (calcitriol) with equal potency. This important characteristic has not been reported for any other radioimmunoassay for 1, 25-dihydroxyvitamin D. The two forms can be assayed in human serum together or individually after HPLC separation. Sample preparation entails acetonitrile extraction followed by C18-Sep-pak chromatography and HPLC. The assay measures 98% of added analyte, and achieves inter- and intra-assay coefficients of variation of 10.7% at 34 pg/ml and 7.8% at 81 pg/ml respectively. The limit of detection is 1.25 pg/tube and 50% displacement of bound ligand is achieved at 14 pg/tube. The reference interval is 20-50 pg/ml, mean 35. The correlation between results from the monoclonal radioimmunoassay and an established polyclonal antibody method was r = 0.98, slope 0.99. The assay has particular application in patients treated with vitamin D2 since 1, 25-dihydroxyvitamin D2 can now be measured accurately in the presence of 1, 25-dihydroxyvitamin D3. © 1990.
    Original languageEnglish
    Pages (from-to)199-209
    Number of pages10
    JournalClinica Chimica Acta
    Volume190
    Issue number3
    Publication statusPublished - 15 Oct 1990

    Keywords

    • 1, 25-Dihydroxyvitamin D2 (ercalcitriol) 1, 25-Dihydroxyvitamin D3 (calcitriol)
    • Monoclonal antibody
    • Radioimmunoassay

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