Compounds containing lipids and proteins (see LIPID; PROTEIN). Most lipids in blood PLASMA are present in this form, and are characterised, according to their densities, as very low (VLDL), intermediate (IDL), low (LD), high (HDL) and very high (VHDL). Concentrations of lipoproteins are key factors in assessing the risk of cardiovascular disease (see HEART, DISEASES OF).