[Differentiation of VLDL subfraction in the diagnosis of type III hyperlipoproteinaemias (author's transl)].

Type III hyperlipoproteinaemias are characterized by "floating" beta-lipoproteins. In lipid electrophoresis these are present as a VLDL subfraction (beta-VLDL). They can also be detected chemically on the basis of the cholesterol/triglyceride ratio of the serum or the corresponding VLDL serum fraction. In the present work, the diagnostic value of these ratios is compared with that of E III peptide loss from VLDL-apolipoproteins, which is thought to be specific for type III hyperlipoproteinaemias. Of 42 persons with a VLDL subfraction, seven showed a loss of the peptide. In these persons, the cholesterol/triglyceride quotient was 0.94+/-0.45 for the whole serum, and 0.59+/-0.25 for the serum VLDL fraction. The quotient for VLDL cholesterol/serum triglyceride was 0.43+/-0,21, and the electrophoretic mobility of the VLDL subfraction was 0.38+/-0.04. Investigation of the VLDL-cholesterol/triglyceride quotient gave four (10%) false positives, while the quotient for VLDL-cholesterol/serum triglyceride gave ten (24%) false positives. This comparison shows that the criteria used for identification of "floating" beta-VLDL subfraction are only indirectly useful in the diagnosis of type III hyperlipoproteinaemia.