[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Fredrickson classification of hyperlipoproteinaemias [Biochemistry](https://durgical.com/en/biochemistry/) · Topic # Fredrickson classification of hyperlipoproteinaemias The Fredrickson system sorts high blood fats into five types by which lipoprotein particle is raised. Each type points to typical causes and risks. Updated 2026-11-01 ## Key facts - Type I: chylomicrons ↑ (LPL or ApoC-II deficiency); very high triglycerides, pancreatitis, eruptive xanthomas, lipaemia retinalis; little atherosclerosis. - Type IIa: LDL ↑ (familial hypercholesterolaemia: LDL receptor, ApoB or PCSK9); tendon xanthomas and early coronary disease. Type IIb: LDL and VLDL ↑ (familial combined hyperlipidaemia). - Type III: remnants/IDL ↑ (familial dysbetalipoproteinaemia, ApoE2/E2); cholesterol and triglycerides both high, palmar and tuberoeruptive xanthomas, 'broad β band'. - Type IV: VLDL ↑ (familial hypertriglyceridaemia and secondary causes: obesity, diabetes, alcohol); the most common phenotype. - Type V: VLDL and chylomicrons ↑; severe hypertriglyceridaemia with risk of acute pancreatitis. ## In detail - 1. It is based on the pattern of lipoproteins seen by electrophoresis and ultracentrifugation (adopted by WHO in 1970), not on genes. - 2. The same phenotype can come from different gene defects, and one family can show different types (for example IIa, IIb and IV in familial combined hyperlipidaemia). - 3. Refrigerator test: a creamy top layer = chylomicrons (types I and V); a turbid whole sample = VLDL (types IV and V); clear plasma = LDL (type IIa). - 4. Secondary causes must be ruled out first: diabetes, hypothyroidism, nephrotic syndrome, cholestasis, alcohol, obesity and drugs (corticosteroids, oestrogens, thiazides, some antiretrovirals, retinoids). - 5. It does not include low HDL or high lipoprotein(a), so treatment decisions today rely on LDL cholesterol, triglycerides, apoB and total cardiovascular risk. - 6. Triglycerides above about 1,000 mg/dL (11 mmol/L) carry a high risk of pancreatitis whatever the type. ## Memory aid Type I = one particle (chylomicron); type IIb = IIa + IV (LDL + VLDL); type V = I + IV (chylomicrons + VLDL). **Also called** WHO/Fredrickson types I–V, Primary hyperlipoproteinaemias ## Clinical notes - Tendon xanthomas suggest type IIa; palmar crease xanthomas suggest type III; eruptive xanthomas suggest types I or V. - Hypothyroidism is a classic secondary cause of high LDL; it should be checked before starting lipid-lowering drugs. - Types I and V are emergencies when triglycerides are very high, because of acute pancreatitis. ## Related conditions - [Familial chylomicronemia syndrome (lipoprotein lipase deficiency)](https://durgical.com/en/conditions/familial-chylomicronemia-syndrome/) - [Familial hypercholesterolemia](https://durgical.com/en/conditions/familial-hypercholesterolemia/) - [Familial dysbetalipoproteinemia (type III hyperlipoproteinemia)](https://durgical.com/en/conditions/familial-dysbetalipoproteinemia/) - [Familial combined hyperlipidaemia](https://durgical.com/en/conditions/familial-combined-hyperlipidaemia/) - [Familial hypertriglyceridaemia](https://durgical.com/en/conditions/familial-hypertriglyceridaemia/) - [Atherosclerosis and dyslipidaemia](https://durgical.com/en/conditions/atherosclerosis-and-dyslipidaemia/) - [Acute pancreatitis](https://durgical.com/en/conditions/acute-pancreatitis/) - [Hypothyroidism](https://durgical.com/en/conditions/hypothyroidism/) ## Related - [Lipoprotein metabolism](https://durgical.com/en/biochemistry/topics/lipoprotein-metabolism/) - [Chylomicron](https://durgical.com/en/biochemistry/topics/chylomicron/) - [VLDL (very-low-density lipoprotein)](https://durgical.com/en/biochemistry/topics/vldl/) - [LDL (low-density lipoprotein)](https://durgical.com/en/biochemistry/topics/ldl/) - [HDL (high-density lipoprotein)](https://durgical.com/en/biochemistry/topics/hdl/) - [Lipoprotein lipase (LPL)](https://durgical.com/en/biochemistry/enzymes/lipoprotein-lipase/) - [LDL receptor](https://durgical.com/en/biochemistry/enzymes/ldl-receptor/) - [Apolipoprotein E (ApoE)](https://durgical.com/en/biochemistry/enzymes/apolipoprotein-e/) - [Apolipoprotein B (ApoB-100 and ApoB-48)](https://durgical.com/en/biochemistry/enzymes/apolipoprotein-b/) - [PCSK9](https://durgical.com/en/biochemistry/enzymes/pcsk9/) - [Centrifugation and ultracentrifugation](https://durgical.com/en/biochemistry/topics/centrifugation-and-ultracentrifugation/) - [Plasma proteins and electrophoresis](https://durgical.com/en/biochemistry/topics/plasma-proteins-and-electrophoresis/) ## Test yourself Think of the answer, then tap the question to see it. ## Which Fredrickson type is caused by lipoprotein lipase or ApoC-II deficiency? Type I (raised chylomicrons), with very high triglycerides and risk of pancreatitis. ## Which lipoproteins are raised in type IIb? LDL and VLDL, as in familial combined hyperlipidaemia. ## Which xanthoma suggests type III, and what genotype causes it? Palmar crease xanthomas (xanthoma striata palmaris); usually ApoE2/E2 homozygosity with a second hit. ## What is the most common Fredrickson phenotype and what is raised? Type IV, with raised VLDL, often worsened by obesity, diabetes or alcohol. ## What does a creamy layer on refrigerated plasma indicate? Chylomicrons, as in types I and V. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/biochemistry/topics/fredrickson-classification-of-hyperlipoproteinaemias/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Familial combined hyperlipidemia: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000396.htm) (MedlinePlus, US National Library of Medicine, 2026); [Familial hypertriglyceridemia: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000397.htm) (MedlinePlus, US National Library of Medicine, 2026); [Familial hypercholesterolemia: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000392.htm) (MedlinePlus, US National Library of Medicine, 2026); [High blood cholesterol levels: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000403.htm) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011). [← All of biochemistry](https://durgical.com/en/biochemistry/) ## **Spotted a mistake?** We are always improving for the community. 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