Radioreceptor Assay for 1α,25-Dihydroxyvitamin D3

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Science  15 Mar 1974:
Vol. 183, Issue 4129, pp. 1089-1091
DOI: 10.1126/science.183.4129.1089


A competitive protein binding assay with a sensitivity of 80 picograms has been developed for 1α,25-dihydroxyvitamin D3, the hormonal form of vitamin D3. lα,25-Dihydroxyvitamin D3 displaced tritiated hormone from a cytosol-chromatin receptor preparation isolated from chick small intestine, providing a simple assay for the hormone. The concentration of lα, 25-dihydroxyvitamin D3 in human plasma, as determined by this assay, is approximately 6 nanograms per 100 milliliters; in patients with renal disease the concentration of this kidney-produced hormone is significantly lower.