Fredrickson classification

The classification according to Fredrickson divides hyperlipoproteinaemias into 6 different types without considering the causes. These biochemical phenotypes can be detected in lipid metabolism disorders of primary or secondary origin.

The serum concentrations of total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides are the basis for the classification. Further parameters are the colour of the fasting serum and the result of the gel electrophoresis.

A single genetic defect (genotype) can result in several different phenotypes. On the other hand, a particular phenotype can be caused by different genetic defects.

• Hyperlipoproteinemia type I: Hyperchylomicronemia (very rare)
• Hyperlipoproteinemia type II: Hypercholesterolemia (autosomal dominant familial hypercholesterolemia)
• Type IIa: isolated elevation of LDL (LDL=low density lipoproteins)
• Type IIb: mixed hyperlipidemia (LDL + VLDL)
• Hyperlipoproteinemia type III: Remnant hyperlipidemia, broad beta disease (IDL+beta VLDL)
• Hyperlipoproteinemia type IV: Hypertriglyceridemia (VLDL)
• Hyperlipoproteinemia type V: Combined hyperlipidemia, endogenous-exogenous hypertriglyceridemia (VLDL+CM)

IDL=Intermediate density-lipoproteins; VLDL = very low density lipoproteins; LDL=low density lipoproteins; CM = Chylomicrons

In practical everyday life, the classification according to Fredrickson is less suitable, since it allows a phenotypic description but does not give any information about the etiology. Also the prognostically important HDL cholesterol is not taken into account.

For the treatment of hyperlipoproteinaemia it is usually sufficient to distinguish between hypercholesterolaemia, hypertriglyceridaemia and combined forms.