Blood Tests to Determine Risk of Coronary Artery Disease

How are blood tests used to determine the risk of heart disease?

Your healthcare provider may order blood and urine lab tests to determine your risk of heart and blood vessel disease. Certain results, like high levels of low-density lipoprotein (LDL), indicate a higher risk of heart disease. The test results and your health history help your healthcare team create the best care plan for you.

When would I need blood tests to determine heart disease risk?

Your healthcare provider may recommend blood tests to determine your risk of heart disease such as coronary artery disease (CAD) if you:

• Eat an unhealthy diet.
• Have a family history of CAD (especially getting diagnosed at age 50 or younger).
• Have obesity or excess weight.
• Don’t get enough physical activity.
• Smoke or use tobacco.
• Have other comorbidities or conditions such as diabetes, high blood pressure, prior heart attack or stroke.

Who performs the blood tests?

A healthcare professional called a phlebotomist or phlebotomy technician usually performs the blood draw. A medical laboratory technician runs the blood sample through a machine that determines the results.

What parts of the blood do the tests measure to find heart disease risk?

When detecting heart disease risk, healthcare providers pay close attention to:

• Total cholesterol (TC): Your total cholesterol is directly linked to your heart and blood vessel disease risk.
• Triglycerides (TG): Triglycerides are related to heart and blood vessel disease. Eating simple sugars and simple carbohydrates, a high-fat diet and drinking alcohol can cause high TG levels. Exercise can help lower levels.
• High-density lipoprotein (HDL): This test identifies your “good cholesterol.” High levels reduce your risk of heart and blood vessel disease.
• Low-density lipoprotein (LDL): LDL is “bad cholesterol.” High levels are linked to a greater risk of heart and blood vessel disease.
• Complete blood count with differential (CBC): This test provides information about different parts of your blood, such as red blood cells, white blood cells and platelets. It can also detect anemia (low red blood cell counts).
• Lipoprotein (a), or Lp(a): Lp(a) is low-density lipoprotein (LDL) attached to a protein called apo (a). High levels of Lp(a) increase your risk of heart attack, stroke, blood clots, fatty buildup in veins after coronary artery bypass surgery and narrowing of coronary arteries after angioplasty.

High levels of Lp(a) tend to run in families. Your provider may order this test if you have a family history of heart disease at an early age.

• Apolipoprotein B (ApoB): ApoB is a major protein found in cholesterol. Research suggests ApoB may be a better overall marker of risk than LDL alone. High levels of ApoB are a sign of small, dense LDLs.
• Homocysteine (Hcy): Hcy is an amino acid. High levels increase your risk of heart and blood vessel disease.
• Hemoglobin A1c (HbA1c): This blood test helps diagnose diabetes, which increases the risk of CAD. It reflects your average blood sugar levels over two to three months.
• Fasting glucose (fasting blood sugar): This test measures your blood sugar levels after a night of fasting. The test can indicate prediabetes and diabetes, which increase heart disease risk.
• Creatine kinase (CK): CK is a muscle enzyme. Levels may be higher if you take medication to lower cholesterol levels.
• Alanine aminotransferase (ALT), or SGPT: This test looks for a liver enzyme. Levels may be higher if you take medication to lower cholesterol.
• Aspartate trans-aminase (AST), or SGOT: This is another liver enzyme. Levels may be higher if you take medication to lower cholesterol.
• Fibrinogen: This test looks for a protein in your blood. Fibrinogen helps your blood clot, but too much increases your risk of a heart attack.
• Thyroid-stimulating hormone (TSH): This test shows how well your thyroid is working. Thyroid dysfunction is linked to heart disease and abnormal heart rhythms.
• Ultra-sensitive C-reactive protein (us-CRP), or high-sensitivity CRP: This test indicates vascular inflammation. Higher levels mean a higher risk of heart and blood vessel disease.
• Urine albumin-creatinine ratio (uACR): This test detects protein in the urine. A small amount of protein in the urine is a risk factor for heart and blood vessel disease. This is part of screening, particularly in people with diabetes.
• MPO: This test indicates inflammation. High levels are linked to a higher risk of heart attack, stroke and the need for coronary artery bypass surgery. High levels can also mean cardiovascular disease is getting worse.
• Vitamin D: This fat-soluble vitamin regulates your body’s calcium and phosphate levels. Calcium and phosphate keep bones healthy. Low levels of vitamin D are linked to various health risks. Low levels can also mean you’re having trouble tolerating a statin (cholesterol medication).
• Trimethylamine N-oxide (TMAO): This substance comes from bacteria in your gut. High levels are found in meat, eggs and dairy foods. Taking choline, lecithin, L-carnitine and other supplements can cause high levels of TMAO. High levels in your blood increase your risk of heart disease, heart attack, stroke and clogged arteries (atherosclerosis).
• Amino-terminal, pro-brain natriuretic peptide, or NT-proBNP: This protein is made in your heart and found in your blood when there’s extra strain on your heart. High levels are linked to a higher risk of heart and blood vessel disease and may signal a decrease in heart function. You may need other tests to get more information.
• Serum creatinine (CR): This substance is related to kidney function. Kidneys that aren’t working properly may stress your heart. Chronic kidney dysfunction could mean a higher heart disease risk. In addition, the heart can stress your kidney as well.
• Atherosclerotic cardiovascular disease (ASCVD) risk score: This score predicts your 10-year risk for atherosclerotic events.

How do I prepare for the blood test?

Before the blood draw, ask your healthcare provider if you should stop taking any medications, vitamins or supplements. Sometimes, certain medications can affect the results of a blood test. Always ask your provider before stopping any medication.

You may need to stop eating or drinking (fast) before a blood test. Ask your healthcare provider in advance if you should fast before the test.

What should I expect during the test?

The phlebotomist inserts a needle into the top of your hand or inside of your elbow. They draw blood from a vein. You may feel a sharp prick as the needle enters your vein. The blood draw usually takes about a minute.

What happens after the blood draw?

After collecting a blood sample, the phlebotomist removes the needle from your vein. They apply light pressure to the blood draw location, then cover it with a bandage.

What type of results will I get, and what do the results mean?

Results vary depending on the different elements of your blood. Your provider will discuss your results with you and any next steps in your care.

This list covers results pertaining to heart disease risk:

Total cholesterol (TC): Your results may differ depending on your age and other risk factors. Ideal results by age:

• 20 years or younger: 75 to 169 mg/dL.
• 21 years or older: 100 to 199 mg/dL.

Triglycerides (TG): The ideal result is less than 150 mg/dL. A very high result (greater than 500 to 1,000 mg/dL) increases your risk of pancreatitis. Levels are usually higher if you have obesity or diabetes.

High-density lipoprotein (HDL): The higher your HDL level, the better. Ideal levels depend on your sex:

• Men and people assigned male at birth (AMAB): Higher than 45 mg/dL.
• Women and people assigned female at birth (AFAB): Higher than 55 mg/dL.

Low-density lipoprotein (LDL): Your ideal result depends on the current state of your health:

• Less than 70 mg/dL if you have heart or blood vessel disease, diabetes or a very high risk of heart disease.
• Less than 100 mg/dL if you have metabolic syndrome or more than one risk factor for heart disease.
• Less than 130 mg/dL if you have a low risk of coronary artery disease.

Complete blood count with differential (CBC): Normal ranges include:

• White blood cell count: 5,000 to 10,000.
• Hematocrit (amount of blood made up of red cells): Men and people AMAB, 40% to 55%; women and people AFAB, 36% to 48%.
• Hemoglobin (part of red blood cell that carries oxygen): Men and people AMAB, 14 to 18 gm/dL; women and people AFAB, 12 to 16 gm/dL.

Lipoprotein (a): An ideal level is less than 30 mg/dL. If your level is high, your healthcare provider will likely discuss how to manage your heart disease risk factors, especially your LDL level.

Apolipoprotein B (ApoB): An ideal level is less than 100 mg/dL.

Homocysteine (Hcy): An ideal level is less than 15 mcmol/L.

Hemoglobin A1c (HbA1c): Results can indicate prediabetes or diabetes. Ideal results for those with diabetes differ from those who don’t have diabetes. In addition, these cutoffs may vary depending on race.

• Ideal level: 6% or lower.
• Prediabetes: 7% to 6.4%.
• Diabetes: 5% or higher.
• Goal for people with diabetes: Less than 6.5% to 7%.

Fasting glucose (fasting blood sugar): An ideal level is less than 100 mg/dL. High levels can mean you have diabetes or insulin resistance:

• Prediabetes: 110 to 125 mg/dL.
• Diabetes: 126 mg/dL or higher on two separate tests.

Creatine kinase (CK): A normal range is 30 to 220 U/L. Levels may be higher if you take medication to lower cholesterol levels.

Alanine aminotransferase (ALT), or SGPT: The normal range is 5 to 45 U/L. Levels may be higher if you take medication to lower cholesterol.

Aspartate trans-aminase (AST), or SGOT: The normal range is 7 to 40 U/L. Levels may be higher if you take medication to lower cholesterol.

Fibrinogen: The normal range is 200 - 400 mg/dL.

Thyroid-stimulating hormone (TSH): The ideal range is 0.4 to 5.5 mIU/mL. This may change if you have had prior thyroid intervention.

Ultra-sensitive C-reactive protein (us-CRP), or high-sensitivity CRP: Results show your level of risk of heart and blood vessel disease:

• Low risk: Less than 2.0 mg/L.
• Intermediate risk: 0 to 3.0 mg/L.
• High risk: Higher than 3.0 mg/L.

Urine albumin-creatinine ratio (uACR): The ideal result is less than 30 mg/g.

MPO: The ideal result is less than <420 pmol/L. If your levels are high, your healthcare provider will discuss how to reduce your risk of cardiovascular problems.

Vitamin D: The ideal range is 31 to 80 ng/ml.

Trimethylamine N-oxide, or TMAO: Results indicate your level of risk of heart disease, heart attack, stroke and clogged arteries (atherosclerosis):

• Low risk: Less than 6.2 uM.
• Intermediate risk:2 to 9.9 uM.
• High risk: 10 uM or higher.

If your levels are high, your healthcare provider will discuss how to lower your LDL and other risk factors. Your provider may recommend taking low-dose aspirin twice a day and following a Mediterranean diet.

Amino-terminal, pro-brain natriuretic peptide, or NT-proBNP: The ideal result is less than 125 pg/mL. If your levels are high, your healthcare provider will discuss how to reduce your risk of cardiovascular problems.

Serum creatinine (CR): Ideal results vary depending on your sex:

• Women and people AFAB:058 to 0.96 mg/dL.
• Men and people AMAB:73 to 1.22 mg/dL.

Atherosclerotic cardiovascular disease (ASCVD) risk score:

• Low risk <5%
• Borderline Risk 5-7.5%
• Intermediate Risk >7.5-<20%
• High risk > 20%

When should I know the results of the test?

It will take at least a few days or longer to receive your blood test results. Ask your healthcare provider how long you can expect to wait before getting your results.

When should I call my provider?

Call your healthcare provider if you haven’t received your test results within a couple of weeks. Your provider will discuss with you the next steps in your care.

A note from Cleveland Clinic

While blood tests help your healthcare provider better understand your heart disease risk, they’re not a definitive diagnosis. If your blood test results show you have an increased risk, your provider may recommend further testing. Talk to your provider about any questions or concerns you have throughout this process.