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[Biochemistry](https://durgical.com/en/biochemistry/) · Topic

# Chylomicron

Chylomicrons are the largest lipoproteins: they carry dietary fat from the gut, through the lymph, to the tissues.

Updated 2026-11-01

## Key facts

- Enterocytes build them after a meal; their structural protein is ApoB-48.
- They are the largest and least dense; about 85–90% of their mass is triglyceride.
- They enter the blood through the lymph and thoracic duct, not the portal vein.
- LPL empties them within minutes; the remnants go to the liver via ApoE.

## In detail

- Formation: MTP loads lipid onto ApoB-48 in the enterocyte ER.
- Maturation: in blood they receive ApoC-II and ApoE from HDL.
- Hydrolysis: capillary LPL frees fatty acids for muscle (fuel) and adipose tissue (storage).
- Remnant: it returns ApoC-II and the liver takes it up via ApoE.
- After a 12-hour fast no chylomicrons normally remain in plasma.

## Clinical notes

- LPL or ApoC-II deficiency piles up chylomicrons: milky plasma, eruptive xanthomas and pancreatitis.
- Without MTP they cannot form: abetalipoproteinaemia, with malabsorption of fat and fat-soluble vitamins.
- Dietary vitamins A, D, E and K travel in chylomicrons.

## Related conditions

- [Familial chylomicronemia syndrome (lipoprotein lipase deficiency)](https://durgical.com/en/conditions/familial-chylomicronemia-syndrome/)
- [Abetalipoproteinemia (Bassen–Kornzweig syndrome)](https://durgical.com/en/conditions/abetalipoproteinemia/)
- [Acute pancreatitis](https://durgical.com/en/conditions/acute-pancreatitis/)

## Related

- [Lipoprotein metabolism](https://durgical.com/en/biochemistry/topics/lipoprotein-metabolism/)
- [Lipoprotein lipase (LPL)](https://durgical.com/en/biochemistry/enzymes/lipoprotein-lipase/)
- [Apolipoprotein B (ApoB-100 and ApoB-48)](https://durgical.com/en/biochemistry/enzymes/apolipoprotein-b/)
- [Apolipoprotein E (ApoE)](https://durgical.com/en/biochemistry/enzymes/apolipoprotein-e/)
- [VLDL (very-low-density lipoprotein)](https://durgical.com/en/biochemistry/topics/vldl/)
- [HDL (high-density lipoprotein)](https://durgical.com/en/biochemistry/topics/hdl/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which structural apolipoprotein does the chylomicron carry?

ApoB-48.

## What does milky serum after a 12-hour fast suggest?

Persistent chylomicrons, as in LPL or ApoC-II deficiency.

## Why does abetalipoproteinaemia cause vitamin E deficiency?

Without chylomicrons fat-soluble vitamins are not absorbed or carried.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Chylomicron assembly (R-HSA-8963888)](https://reactome.org/PathwayBrowser/#/R-HSA-8963888) (Reactome, 2026); [Familial lipoprotein lipase deficiency: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000408.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).

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