Abstract: The present invention provides methods and reagents for assessing lipoprotein metabolism. The methods provided are applicable for use on multiple samples in a clinical laboratory, thus obviating the need for sophisticated instrumentation, such as flow cytometry. Selected cell types in a test sample are uniformly labelled with a detectable reporter substance, so that they may later be enumerated. Pre-determined lipoprotein receptors associated with the cells of interest are labelled with a receptor-selective marker, thereby to determine the number of lipoprotein receptors per cell in the test sample. Selected cells of interest are conveniently separated from the test sample by binding thereto a specific binding substance attached to a solid support. The specific binding substance binds specifically with a characteristic determinant of the cell subset of interest. The remainder of the test sample may be washed away or discarded.