Hyperlipoproteinemia

Hyperlipoproteinemia is the presence of elevated levels of lipoprotein in the blood. Lipids (fatty molecules) are transported in a protein capsule, and the density of the lipids and type of protein determines the fate of the particle and its influence on metabolism.

Although the terms hyperlipoproteinemia and hypercholesterolemia are often used interchangably, the former is more specific.

Hyperlipoproteinemias are classified according to the Fredrickson/WHO classification (Fredrickson et al 1967), which is based on the pattern of lipoproteins on electrophoresis or ultracentrifugation.

Hyperlipoproteinemia type I

This very rare form, also known as Buerger-Gruetz syndrome is due to high chylomicrons, the particles that transfer fatty acids from the digestive tract to the liver.

Hyperlipoproteinemia type II

Hyperlipoproteinemia Type II is hyperlipidemia (hypercholesterolemia) in the Fredrickson classification, which is determined by lipoprotein electrophoresis.

Hyperlipoproteinemia type II is further classified into:

• Type IIa (elevated LDL only)
  • Polygenic hypercholesterolaemia
  • Familial hypercholesterolemia (FH)
• Type IIb - combined hyperlipidemia (elevated LDL and VLDL, leading to high triglycerides levels)
  • Familial combined hyperlipoproteinemia
  • Secondary combined hyperlipoproteinemia

Hyperlipoproteinemia type III

This form is due to high chylomicrons and IDL (intermediate density lipoprotein).

Hyperlipoproteinemia type IV

This form is due to high triglycerides.

Hyperlipoproteinemia type V

This type is very similar to Type I, but with high VLDL.

Unclassified forms

Non-classified forms are extremely rare:

• Hypo-alpha lipoproteinemia
• Hypo-beta lipoproteinemia

References

• Fredrickson DS, Levy RI, Lees RS. Fat transport in lipoproteins: an integrated approach to mechanisms and disorders. N Engl J Med 1967;276:148-156. PMID 5334266.

External links

• The Fredrickson papers (with photos from early lipoprotein research
• GP notebook