Blood sample assay method
The invention provides an enzymatic method for measuring the concentration of one or more analytes in the plasma portion of a blood derived sample, containing a first and a second component, where said second component interferes with the measurement of said first component. The method includes: i) diluting the sample with a reagent mixture; ii) substantially removing blood cells; iii) using a reagent which serves to temporarily prevent reaction of the second component, to generate a blocked second component; iv) causing the selective reaction of a constituent of each analyte to directly or indirectly generate detectable reaction products, where one of the analytes is the first component; v) monitoring the detectable reaction product or products; vi) relating an amount of the detectable product or products and/or a rate of formation of the detectable product or products to the concentration of each analyte, where the concentration of at least the first component is related to a corresponding detectable reaction product by means of estimating an un-measurable (fictive) endpoint. Step iii) may be carried out at any stage up to and including step iv) but before steps v) or vi). The reagent of step iii) may be applied to the sample separately or may be included in a reagent mixture during steps i) or iv). A corresponding kit is also provided.
1. A kit for use in determining the concentrations of at least three different analytes in a sample comprising HDL and non-HDL, wherein said HDL interferes with the measurement of said non-HDL if said HDL is present and unblocked, said kit comprising:
a) a first reagent mixture formulated to dilute said sample;
b) a cell separation unit;
c) a first blocking reagent that temporarily and/or competitively prevents reaction of HDL in said sample, thereby producing blocked HDL;
d) a second reagent mixture comprising a first converting enzyme that converts a first analyte to a first detectable product;
e) a third reagent mixture comprising a second converting enzyme that converts a second analyte to a second detectable product; and
f) a fourth reagent mixture comprising a third converting enzyme that converts a third analyte to a third detectable product.
2. The kit of claim 1 wherein said first reagent mixture comprises said first blocking reagent.
3. The kit of claim 1 wherein one of said at least three different analytes is total cholesterol, total triglycerides, or non-HDL associated cholesterol.
4. The kit of claim 1 wherein said sample is whole blood.
5. The kit of claim 1 wherein said sample is a plasma portion of a blood sample.
6. The kit of claim 1 wherein said first blocking reagent blocks HDL for at least 60 seconds.
7. The kit of claim 1 wherein one of said at least three different analytes is non-HDL triglycerides.
8. The kit of claim 1 wherein one of said at least three different analytes is non-HDL phospholipids.
9. The kit of claim 1 wherein one of said at least three different analytes is non-HDL cholesterol.
10. The kit of claim 1 wherein said indirect products are detectable photometrically.
11. The kit of claim 1 further comprising computer readable media comprising instructions for performing an algorithm to predict an unmeasurable or fictive end-point for an enzymatic reaction.
12. The kit of claim 1 further comprising a lysing agent.
13. The kit of claim 1 further comprising a detergent.
14. The kit of claim 1 further comprising a calibrator or control sample.
15. The kit of claim 1 wherein said first blocking reagent reacts with HDL to produce blocked HDL.
16. The kit of claim 1 wherein said cell separation unit removes blood cells from a sample diluted with said first reagent mixture.