Abstract: A patient's health may be diagnosed by centrifuging blood samples in a transparent tube, which tube contains one or more bodies or groups of bodies such as floats, inserts, liposomes, or plastic beads of different densities. Each density-defined body carries analyte-capture binding materials such as antigens or antibodies, which are specific to an epitope, or other specific high affinity binding site on a target analyte which target analyte may be in the blood or other sample being tested; and the level of which analyte is indicative of the patient's health. At least one labeled binding material which is also specific to an epitope, or other specific high affinity binding site on the target analyte is added to the sample so as to form labeled binding material/analyte/body complexes in the sample.