Apolipoprotein B

UK laboratories print a range of upper limits, commonly 1.3 or 1.4 g/L as a population range, with some printing lower figures used as targets; ranges differ between methods.

Apolipoprotein B is the main protein on the surface of LDL and the other cholesterol-carrying particles that can deposit in artery walls. There is one apolipoprotein B molecule per particle, so measuring it counts those particles directly, whatever amount of cholesterol each one carries. It is usually reported alongside apolipoprotein A1.

Doctors and lipid clinics request it for a more detailed look at lipid particles than the standard profile gives, especially where triglycerides are high or there is a family pattern of heart disease, and to follow the effect of cholesterol-lowering medicines.

• A diet high in saturated fat
• Family patterns of high cholesterol
• Being overweight, type 2 diabetes and insulin resistance
• An underactive thyroid
• Kidney disease with protein loss in the urine

• Cholesterol-lowering medicines such as statins, ezetimibe and PCSK9 inhibitors
• Weight loss and changes in diet
• An overactive thyroid
• Long-term illness and poor nutrition
• Rare inherited conditions of lipid handling

• It falls for several weeks after any acute illness
• Methods differ between laboratories, so figures from two labs are not directly comparable

No fasting needed. Read alongside apolipoprotein A1 and the standard lipid profile; the trend matters more than a single value.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.