Diagnosis of Type IllHyperlipoproteinemia

Sera of normal subjects and of patients with different typesof hyperlipoproteinemiawere dividedintofive groups accordingto the amountof intermediate lipoproteins in the f3-pre-f3-region after electrophoresis of serum and the very-low-density lipoprotein (VLDL)fraction. These sera were further studied as to the lipid composition of their VLDL and as to the outcome of different diagnostic tests for type Ill hyperlipoproteinemia. Application of the diag- nostic methods revealed that the percentage of positive findingsgradually increasedfrom group ito 5. (loup 5 met all the criteria and the patients in this groupwere therefore characterizedas havingtype Ill hyperlipoproteinemia.The patientsin group4, althoughnot meetingall the criteria for type Ill, were nevertheless considered as such, the elec- trophoretic patternbeingdecisive.The resultssuggestthat two different forms of type III may exist. The results of the methods used for the diagnosis of type Ill hyperlipopro- teinemia appeared to be related to the serum concentra- tions of cholesterolandtriglycerides.During therapy, there are changesin the electrophoretic characteristics of serum and the VLDL-fraction of patients with type Ill hyperlipo- proteinemia; polyanion precipitation becomes less fre- quently positive and the ratios VLDL-cholesterol/serum triglycerides and VLDL-cholesterol/VLDL-triglycerides are lowered. These results give a better insight into the value of the different diagnostic criteria used for the diagnosis of type Ill hyperlipoproteinemia. Several methods are used for the diagnosis of type III by- perlipoproteinemia. At first, the detection of VLDL' with fl-mobility on paper electrophoresis was considered to be di- agnostic (1). Later, other methods were introduced, based on the abnormal lipid composition of the VLDL, such as the determination of VLDL-chol/VLDL-TG (2) and VLDL- chol/serum TG (3). A combined agarose gel electrophoresis- polyanion precipitation method was also considered to be diagnostic for type III hyperlipoproteinemia (4). For more precise diagnosis of type III hyperlipoproteinemia, it seemed necessary to standardize the description of the electrophoretic patterns. With application of an improved agarose method, the electrophoretic behavior of the VLDL-