Apolipoprotein A-1 ApoA-1 Lipid Panel

Apolipoprotein A-1 (ApoA-1) Test: The Protein Behind 'Good Cholesterol'

ApoA-1 is the protein that builds HDL and switches on its cleanup work. HDL cholesterol weighs what the particle is carrying; ApoA-1 counts the particles doing the carrying. It is the number behind the famous one, and the one your doctor rarely orders by name.

Reference range
110–180 mg/dL Adult Male
110–205 mg/dL Adult Female
LOINC code
1869-7 on loinc.org

Universal lab test identifier

Also reported as
Apolipoprotein A-I Apo A-I Apo A ApoA1

Part of the Lipid Panel — see all 10 values together, including HDL Cholesterol, Total Cholesterol, LDL Cholesterol.

Apolipoprotein A-1 (ApoA-1) is the main protein in HDL, the particles that carry cholesterol from the tissues back to the liver. An ApoA-1 test measures that protein in a blood sample, reported in mg/dL in the US and in g/L in many other countries. It is not part of a standard cholesterol test.

Doctors add it when the HDL side of a lipid result needs explaining: a very low HDL, heart disease at a young age in the family, or a suspected inherited HDL disorder. A low ApoA-1 means fewer or less effective HDL particles and is read as a higher heart risk; a high ApoA-1 mostly reflects a high HDL.

How ApoA-1 differs from HDL cholesterol

The HDL cholesterol on every lipid panel measures the cholesterol that HDL particles happen to be carrying. ApoA-1 measures the protein the particles are built on, which makes it closer to a count of the particles themselves. A useful comparison is a sculptor's wire frame and the clay on it: HDL cholesterol weighs the clay, ApoA-1 counts the frames.

The protein does real work. It pulls cholesterol and phospholipids out of cells to form new HDL particles, and it switches on the reaction that turns loose cholesterol into a form HDL can carry to the liver. ApoA-1 makes up 60 to 70 percent of HDL's protein, so in most people the two results move together.

Normal ApoA-1 levels

ApoA-1 ranges

mg/dL (g/L)
Low < 110

Below most adult ranges (under about 1.1 g/L), and usually seen together with a low HDL cholesterol.

Lower end of typical 110–150

Where many men and some women sit (about 1.1 to 1.5 g/L). How reassuring it is depends on the rest of the lipid results.

Favorable 150–200

About 1.5 to 2.0 g/L, more common in women. Generally goes with lower heart risk.

High > 200

Mostly reflects a high HDL. As with HDL, a very high value is not automatically extra protection.

Ranges differ by sex more than for most tests, which is why the lab asks for sex on the order. Labcorp's adult interval is 101 to 178 mg/dL for males over 12 and 116 to 209 mg/dL for females, so a result of 112 is normal for a man and low for a woman. Female hormones raise HDL and its protein, an advantage that narrows after menopause. Regular exercise and a leaner build raise ApoA-1 as well.

Check the unit when comparing reports. US labs use mg/dL and many others g/L, a factor of 100 apart: 120 mg/dL is 1.2 g/L, so "1.4" and "140" can be the same sample. The guide to SI and conventional units explains why.

What a low ApoA-1 means

A result under about 110 mg/dL (1.1 g/L) means fewer or less capable HDL particles. It almost always comes with a low HDL cholesterol, because the two describe the same particle, and on its own it does not point to a specific disease. It carries much the same meaning for cardiovascular risk as a low HDL and is weighed the same way, as one part of an overall heart risk estimate with blood pressure, blood sugar, the other lipids and family history.

Common reasons for a low ApoA-1

  • High triglycerides and insulin resistance

    High triglycerides pull HDL and its protein down together, the pattern that goes with excess weight and low activity.

  • Smoking

    Lowers HDL, more strongly in women; levels tend to recover after quitting.

  • Chronic conditions

    The NHLBI lists chronic kidney disease, diabetes, an underactive thyroid, lupus, HIV, polycystic ovary syndrome and sleep apnea among conditions that lower HDL.

  • Medicines

    Including beta blockers, thiazide diuretics, steroids such as prednisone, acne retinoids, cyclosporine, amiodarone and some chemotherapy drugs.

  • Inherited causes

    Familial HDL deficiency causes low HDL from a young age, sometimes with heart disease before 50. Tangier disease, caused by ABCA1 gene variants, is much rarer, with around 100 cases identified worldwide.

When a low ApoA-1 comes with a low HDL and high triglycerides, the next tests are usually fasting glucose or HbA1c to look for insulin resistance, rather than more lipid tests. A very low level with no explanation in the history leads to a look at inherited causes.

When ApoA-1 is worth measuring

For most people ApoA-1 repeats what HDL cholesterol already shows, at a higher cost, which is why it stays off routine orders. Labcorp lists two main uses: refining heart risk when HDL is low, and helping identify Tangier disease, in which HDL is almost absent. ApoA-1 itself needs no fasting, so if it is drawn with a lipid panel, the panel's instructions apply.

It is also ordered as a pair with apolipoprotein B, which counts the particles that build plaque in artery walls. How the two are read together, including the ApoB/ApoA-1 ratio, is covered in the ApoB vs ApoA-1 comparison.

A single ApoA-1 result rarely changes treatment on its own; decisions about cholesterol-lowering treatment are based on LDL cholesterol or ApoB and on overall risk. The guide to reading cardiac markers shows where each number fits. ApoA-1 changes over months with lifestyle, so a repeat a few months after a real change says more than one after six weeks, and a value of 120 means more when compared with earlier results, as tracking results over time explains.

Sources

Written and reviewed by BloodSight Editorial Team · Last updated

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Normal ranges

Group Range Unit
Adult Male 110–180 mg/dL
Adult Female 110–205 mg/dL

Reference ranges may vary by laboratory and individual factors.

Apolipoprotein A-1 — Common Questions

What does an apolipoprotein A-1 test measure?
It measures the amount of ApoA-1 protein in blood serum, usually in mg/dL. ApoA-1 makes up 60% to 70% of the protein content of HDL, so the result tracks how much functioning HDL machinery is circulating rather than how much cholesterol those particles happen to be carrying. Labcorp runs it as an immunologic assay on serum, with plasma accepted as an alternative.
What is a normal ApoA-1 level?
It depends on the lab, your sex and the assay. Labcorp's adult interval runs 101 to 178 mg/dL for males over 12 and 116 to 209 mg/dL for females, and women generally read higher than men at every age. Some labs report in g/L, where 120 mg/dL is 1.2 g/L. Compare your value with the interval printed on your own report.
Is an ApoA-1 of 120 good?
An ApoA-1 of 120 mg/dL (1.2 g/L) sits inside most adult reference intervals but near the bottom of them, and closer to the bottom for a woman than for a man. On its own it is neither reassuring nor alarming. What it means depends on your HDL, triglycerides, LDL and overall heart risk, and on whether earlier results were higher.
Do I need to fast for an ApoA-1 test?
Labcorp's entry lists no fasting requirement for ApoA-1 itself. In practice it is usually drawn alongside a lipid panel, and the panel's instructions govern the whole order, so ask the clinic rather than deciding per test. If you were told to fast for the other tests in the draw, fasting does not interfere with this one.
What causes a low apolipoprotein A-1?
Most low results come from the same things that lower HDL cholesterol. The NHLBI lists smoking, excess weight, inactivity, chronic kidney disease, diabetes, hypothyroidism, lupus, HIV, PCOS and sleep apnea, along with medicines including beta blockers, thiazide diuretics, prednisone, acne retinoids and cyclosporine. Rare inherited causes such as familial HDL deficiency and Tangier disease produce very low values from childhood.
Can ApoA-1 be low when HDL cholesterol is normal?
Yes, though it is uncommon. The two measure the same particles from different angles, so they usually move together. A gap between them means your HDL particles carry more or less cholesterol each than average, which no routine test resolves further. Most clinicians treat a mismatch as a reason to read the full lipid picture rather than either number alone.
How can I raise a low ApoA-1?
Ask your doctor first, because the plan depends on why it is low. For raising HDL and its protein the NHLBI points to regular physical activity, quitting smoking, losing excess weight and limiting alcohol, which move the numbers over months rather than weeks. No drug that raises HDL-related markers has been shown to prevent heart attacks, so treatment targets overall risk instead.

Disclaimer

This content is for informational and educational purposes only. It is not intended as medical advice, diagnosis, or treatment recommendation. Reference ranges may vary by laboratory. Always discuss your results with a qualified healthcare professional.

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