We propose to investigate human in vivo lipoprotein metabolism using radiolabeled apolipoproteins on plasma lipoproteins. Paired kinetic studies using dual-labeled iodinated lipoproteins and apolipoproteins are performed in healthy volunteer controls with normal lipids and subjects with dyslipidemia under controlled metabolic conditions. Studies are designed to formulate metabolic pathways in patients with undefined genetic disorders of lipid metabolism as well as in healthy volunteers to provide original insights into normal and pathologic metabolic pathways. All kinetic data is computer analyzed to provide quantitative data and facilitate direct comparison of multiple studies.