24-25-dihydroxyvitamin-d-3 and Calcium-Metabolism-Disorders

Reliable assays to determine the vitamin D metabolites are useful aids in the study of disorders involving vitamin D metabolism, and in the evaluation of the response in patients receiving vitamin D treatment. We report here the establishment in our laboratory of a method capable of measuring 25(OH)D, (including 25(OH)D2 and 25(OH)D3), 1,25(OH)2D and 24,25(OH)2D in a single blood sample. The method involves methanol/dichloromethane extraction and Sephadex LH-20 chromatography. The monhydroxylated fraction was purified on Lipidex 5000 and separated in 25(OH)D2 and 25(OH)D3 on high pressure liquid chromatography (HPLC), followed by ultra violet absorbance (UV) detection. The dihydroxylated fraction was separated by HPLC and quantified by protein-binding assays. The method is precise and accurate. The vitamin D metabolites were measured in different groups of patients and in normal subjects.

Topics: 24,25-Dihydroxyvitamin D 3; Calcifediol; Calcitriol; Calcium Metabolism Disorders; Chromatography, Gel; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Humans; Radioligand Assay; Reference Values

Male Wistar rats that were experimentally hypokinetic were fed 24,25(OH)2D3 or 1,25(OH)2D3 separately or in combination to determine the effect on bone growth and on bone formation and resorption. It was shown that these parameters of bone metabolism are influenced by these metabolites of vitamin D3 by their effect on bone sensitivity to their activity and perhaps in the regulation of bone histogenesis.

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Bone Development; Calcitriol; Calcium Metabolism Disorders; Cholecalciferol; Dihydroxycholecalciferols; Epiphyses; Femur; Growth Plate; Immobilization; Male; Movement; Phosphorus Metabolism Disorders; Rats; Rats, Inbred Strains