25OH Vitamin D Total, RIA CT, 384 tests

At first calibrators, controls and samples (serum or heparin plasma) are pre-treated to release 25OH Vitamin D2 and 25OH Vitamin D3 from Vitamin D Binding Protein (DBP). A fixed amount of 125I labelled 25OH Vitamin D competes with the 25OH Vitamin D2 and 25OH Vitamin D3 from treated samples, controls or calibrators, for a fixed amount of a specific monoclonal antibody sites immobilized to the lower and inner surface of plastic tubes. After 2 hours incubation at room temperature on a tube shaker, an aspiration step terminates the competition reaction. The tubes are then washed twice and aspirated again. A calibration curve is plotted and the total 25 OH Vitamin D (D2 and D3) concentrations of the samples are determined by dose interpolation from the calibration curve.