Lipoprotein fractions in idiopathic hyperlipoproteinaemia.
The purpose of the study was an assessment of the lipid and protein composition of very low density lipoproteins (VLDL) in hyperlipoproteinaemias type IIa, IIb, III and IV. Besides that, cholesterol was determined in low density lipoproteins (LDL) and high density lipoproteins (HDL). Fifty-seven patients with idiopathic hyperlipoproteinaemia and nineteen subjects without lipid metabolism disturbances were studied. The VLDL fraction was obtained by ultracentrifugation of the serum. The LDL and HDL fractions were separated by precipitation. A raised value of the LDL:HDL cholesterol ratio was found in hyperlipoproteinaemias type IIb, III and IV. Positive correlations between the concentrations of lipid and protein components of the VLDL fraction were found in hyperlipoproteinaemias type IIa, IIb, IV and in normolipaemia, which suggests maintained proportions between VLDL components. The high proportion of cholesterol in the VLDL fraction in relation to other components in type III hyperlipoproteinaemia indicates an abnormal composition of this fraction.