In this article
LDL cholesterol and apolipoprotein B (ApoB) both relate to how cholesterol moves through the blood. LDL is one of the levels a standard cholesterol test measures (MedlinePlus). ApoB is a protein that plays a role in moving cholesterol around the body, and it can be measured with its own blood test (MedlinePlus).
This guide explains what each one is and what public health sources say about how they compare.
Lipoproteins in brief
Cholesterol is a waxy, fat-like substance found in all the cells of the body. To move through the blood, it attaches to proteins. These combinations of fat (lipid) and protein are called lipoproteins. HDL, LDL and VLDL are all lipoproteins (MedlinePlus).
What LDL is
LDL stands for low-density lipoprotein. It is sometimes called "bad" cholesterol because a high LDL level leads to a buildup of cholesterol in the arteries. This buildup, called plaque, is the condition known as atherosclerosis (MedlinePlus).
A standard cholesterol test, also called a lipid panel, measures LDL, HDL and total cholesterol, along with triglycerides, a type of fat (MedlinePlus).
What ApoB is
MedlinePlus describes apolipoprotein B (ApoB) as a protein that plays a role in moving cholesterol around the body, and as a form of LDL (MedlinePlus). The ApoB test measures the level of ApoB100 in the blood.
According to MedlinePlus, the test is most often done to help find the cause or specific type of high blood cholesterol. Variants in the gene behind ApoB100 can cause familial hypercholesterolemia, a form of high cholesterol that runs in families (MedlinePlus).
How they compare
| LDL cholesterol | ApoB | |
|---|---|---|
| What it is | A lipoprotein, a combination of fat and protein that carries cholesterol (MedlinePlus) | A protein that plays a role in moving cholesterol around the body (MedlinePlus) |
| How it's measured | Part of a standard cholesterol test, or lipid panel (MedlinePlus) | Its own blood test (MedlinePlus) |
| Other names | Low-density lipoprotein, "bad" cholesterol | ApoB100, apolipoprotein B100 |
So which number matters more?
There isn't a settled answer. MedlinePlus notes that how much the ApoB test adds to standard cholesterol testing is not known. It also notes that ApoB measurements may provide more detail about heart disease risk (MedlinePlus).
Researchers continue to study how the two measures compare.
When to see a clinician
Questions about cholesterol, or about any change in health, are best discussed with a licensed clinician who knows a person's history. In a medical emergency, call 911 or go to the nearest emergency room.
Frequently asked questions
What does ApoB stand for? Apolipoprotein B. The ApoB test measures ApoB100, which is also called apolipoprotein B100 (MedlinePlus).
What is a lipoprotein? A combination of fat (lipid) and protein. Cholesterol attaches to proteins so it can move through the blood (MedlinePlus).
Why is LDL called "bad" cholesterol? Because a high LDL level leads to a buildup of cholesterol, called plaque, in the arteries (MedlinePlus).
What does a standard cholesterol test measure? LDL, HDL and total cholesterol, along with triglycerides (MedlinePlus).
- MedlinePlus. Cholesterol.
- MedlinePlus. LDL: the "bad" cholesterol.
- MedlinePlus. Cholesterol levels.
- MedlinePlus. Apolipoprotein B.
The information in this article is for general educational purposes only. It is not medical advice and is not a substitute for diagnosis or treatment from a qualified clinician who knows your history. Don't start, stop or change any treatment based on this article. If you think you're having a medical emergency, call 911 or go to the nearest emergency room. Reading this article does not create a clinician-patient relationship with Tenor Health or any provider on our platform.
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