title: 1,25-Dihydroxyvitamin D in biological fluids: a simplified and sensitive assay.
abstract: A competitive binding assay for 1,25-dihydroxyvitamin D [1,25-(OH2D] in plasma has been developed in which intestinal cytosol preparations from rachitic chicks are used as the binding protein. A new method of extraction and two new chromatographic procedures are used for this assay. The method is sensitive to as little as 10 picograms of 1,25-(OH)2D, and triplicate assays can be done on 5 milliliters of plasma. This assay shows that in the plasma of normal adult subjects there is a 1,25-(OH)2D concentration of 29 +/- 2 picograms per milliliter, while none can be detected in the plasma of nephrectomized subjects and end-stage renal failure patients.
mesh_terms: D000367:Age Factors; D001667:Binding, Competitive; D004100:Dihydroxycholecalciferols / Q000097:blood*; D004386:Duodenum / Q000378:metabolism; D004872:Ergocalciferols / Q000031:analogs & derivatives / Q000097:blood*; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood*; D007413:Intestinal Mucosa / Q000378:metabolism; D007676:Kidney Failure, Chronic / Q000097:blood; D011955:Receptors, Drug; D012279:Rickets / Q000378:metabolism
chemical_list: D004100:Dihydroxycholecalciferols; D004872:Ergocalciferols; D006887:Hydroxycholecalciferols; D011955:Receptors, Drug