Blood sample assay method

Inventors

Faaren, Arne Ludvig • Frantzen, Frank • Nordhei, Arne Kristian • Sundrehagen, Erling • Ørning, Lars

Assignees

Abbott Rapid Diagnostics International ULC

Abstract

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.

Core Innovation

The document describes an enzymatic point-of-care blood assay for measuring cholesterol associated with a non-HDL component in the plasma portion of a blood-cell containing sample. The sample contains both a non-HDL component and an HDL component, which also comprises cholesterol, and the method measures the concentration associated with the non-HDL component without requiring a non-HDL calibration standard.

The method dilutes the sample, substantially removes blood cells to provide a substantially cell free sample, and contacts the sample with a blocking reagent for the HDL component. The blocking reagent temporarily blocks access to cholesterol from the HDL component while cholesterol from the non-HDL component remains accessible to a cholesterol converting enzyme, and the sample is then contacted with at least one converting enzyme that reacts specifically with the cholesterol associated with the non-HDL and generates one or more detectable reaction products.

Rather than requiring a measurable reaction end-point, calibrators, or dried reagents, the method monitors the detectable reaction product or products and relates the amount of detectable product to the concentration of the cholesterol associated with the non-HDL component by estimating an un-measurable (fictive) endpoint using an algorithm. The algorithm-estimated fictive endpoint is used to estimate the concentration of non-HDL-associated cholesterol, and the HDL blocking step can be carried out at a stage up to and including the converting-enzyme step but before product monitoring or concentration relating.

Claims Coverage

The independent claim is clm-00001. It contains three core inventive features: measuring non-HDL-associated cholesterol without a non-HDL calibration standard, temporary HDL blocking combined with non-HDL selective conversion, and product monitoring with concentration determination via an algorithm estimating an un-measurable (fictive) endpoint. Dependent claims add constraints and refinements, including cell-free sample constraints, filtration, specific HDL blocking reagent characteristics, sample volume limits, and algorithm forms.

Across clm-00001, the claim coverage centers on measuring non-HDL-associated cholesterol in blood without requiring a non-HDL calibration standard by combining dilution and substantially cell-free sample preparation, temporary HDL blocking to keep HDL cholesterol inaccessible while non-HDL cholesterol remains accessible to a cholesterol converting enzyme, and detecting conversion products while using an algorithm to estimate a fictive un-measurable endpoint for concentration determination.

Stated Advantages

Documented Applications