ApoA1 test: normal range, low levels and the ApoB/ApoA1 ratio

Quick answer: on an ApoA1 test, Mayo Clinic Laboratories reports adult ApoA1 of 120 mg/dL (1.2 g/L) or more as acceptable for men and 140 mg/dL (1.4 g/L) or more for women. For ages 2 to 17, under 115 mg/dL is low and over 120 acceptable. Cleveland Clinic gives 100 to 150 mg/dL as a general normal range. ApoA1 is most useful next to ApoB, as the ApoB/ApoA1 ratio.

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ApoA1 normal range

ApoA1 is reported in mg/dL in the US and g/L elsewhere (divide mg/dL by 100). Unlike LDL or ApoB, there is no guideline treatment goal for ApoA1; it is used to assess risk.

What is ApoA1?

Apolipoprotein A1 is the main protein in HDL particles, the ones that carry cholesterol away from tissues back to the liver. Cleveland Clinic notes that a low ApoA1 usually comes with low HDL, and Mayo Clinic Laboratories states that low ApoA1 raises the risk of atherosclerotic heart disease. The test also helps diagnose Tangier disease, a rare inherited condition with very low HDL.

HDL cholesterol and ApoA1 usually move together, so why measure both? HDL-C tells you how much cholesterol the HDL particles hold; ApoA1 tells you about the particles themselves, and it is the number that pairs with ApoB in the ratio. Neither is a treatment target in the 2026 ACC/AHA guideline, which builds treatment around LDL and non-HDL cholesterol, but both help show where your risk comes from.

The ApoB/ApoA1 ratio

ApoB counts the particles that deposit cholesterol in arteries; ApoA1 reflects the particles that remove it. The ratio puts the two in one number. In INTERHEART, a study of about 30,000 people in 52 countries (Lancet, 2004), a raised ApoB/ApoA1 ratio was one of the strongest risk factors for a first heart attack: people in the top fifth had 3.25 times the odds of those in the bottom fifth, and the ratio accounted for an estimated 49% of the population attributable risk.

The ratio is simple arithmetic: divide ApoB by ApoA1 in the same unit. An ApoB of 90 mg/dL with an ApoA1 of 150 mg/dL gives 0.60; an ApoB of 130 with an ApoA1 of 110 gives about 1.18. Lower is better. Cleveland Clinic notes some researchers think the ratio may predict blood vessel disease better than the total cholesterol:HDL ratio. There is no single agreed cutoff in US guidelines, so track the trend and read it next to your ApoB.

Worked example: low ApoA1 and a borderline ApoB

Say a 55-year-old woman who smokes gets an ApoA1 of 128 mg/dL, HDL of 44 mg/dL and ApoB of 118 mg/dL. Her ApoA1 is inside Cleveland Clinic's general 100 to 150 mg/dL range but 12 mg/dL under the 140 mg/dL that Mayo Clinic Laboratories uses for adult women. Her HDL is under the 50 mg/dL low line for women (see our HDL page), and her ApoB is borderline high on the scale in our ApoB guide. Her ApoB/ApoA1 ratio is 118 divided by 128, about 0.92, against 0.60 in the first example above.

What might explain it: tobacco use is first on Cleveland Clinic's list of causes of low ApoA1, followed by unmanaged diabetes, kidney failure and medicines such as beta-blockers and diuretics.

Questions to take to her doctor:

• ApoB and LDL are what treatment targets, so what goal applies to my ApoB of 118?
• Should I check HbA1c, since unmanaged diabetes lowers ApoA1?
• What help is there to stop smoking, and when should we recheck the ratio?

What low ApoA1 means

Low ApoA1 points to low HDL and a higher risk of heart and blood vessel disease. Cleveland Clinic lists these causes:

• Tobacco use
• Unmanaged diabetes
• Kidney failure
• Some medicines, including beta-blockers and diuretics

Rare inherited conditions, including ApoA1 deficiency and Tangier disease, also cause very low levels (Mayo Clinic Laboratories; Cleveland Clinic).

What high ApoA1 means

Cleveland Clinic calls a high ApoA1 "a good thing" that usually causes no problems. Higher levels are seen with physical activity, weight loss, pregnancy, estrogen and statins or other cholesterol drugs.

What raises ApoA1

Research cited by Cleveland Clinic finds higher ApoA1 in people who:

• Are physically active
• Do not use tobacco
• Have a lower BMI
• Follow a Mediterranean diet

These are the same habits that lower ApoB, so they improve the ratio from both ends. If you take a medicine that lowers ApoA1, do not stop it; ask your doctor.

ApoA1 test: how it is done

ApoA1 is a standard blood test, but it is not on a basic lipid panel and is usually ordered with ApoB. Fasting rules depend on the lab and on whether a lipid panel is drawn at the same time. Test under the same conditions each time so the trend means something.

When you get the result, ask three things: is it above the cutoff for your sex, how does it compare with your HDL, and what is the ApoB/ApoA1 ratio? If ApoA1 is low and ApoB is high, the conversation with your doctor should be about ApoB and LDL, since those are what treatment targets.

Which at-home tests include ApoA1

ApoA1 is on two SiPhox panels: Longevity Essentials and Ultimate 360. Heart & Metabolic, GLP Optimization, Thyroid Focus and Hormone Focus do not include it, even though Heart & Metabolic and GLP Optimization have ApoB.

Both panels also report the ApoB:ApoA1 ratio and LDL-C:ApoB ratio, and both are collected with the needle-free EasyDraw device on the upper arm. SiPhox does not include a doctor review, so discuss results with your doctor. See the ApoB test guide, the longevity blood test comparison and our SiPhox review.

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