Blood tests for heart disease

By Mayo Clinic Staff


Your blood offers many clues about your heart health. For example, high levels of "bad" cholesterol in your blood can be a sign that you're at increased risk of having a heart attack. And other substances in your blood can help your doctor determine if you have heart failure or are at risk of developing plaques in your arteries (atherosclerosis).

It's important to remember that one blood test alone doesn't determine your risk of heart disease and that the most important risk factors for heart disease are smoking, high blood pressure, high cholesterol and diabetes.

Click on the tabs at the left to look at some blood tests you may have in your diagnosis, treatment and management of heart disease.

C-reactive protein

C-reactive protein

C-reactive protein (CRP) is a protein your liver produces as part of your body's response to injury or infection (inflammatory response).

CRP is a sign of inflammation somewhere in the body. However, CRP tests can't pinpoint where in the body this may be happening. Inflammation plays a central role in the process of atherosclerosis, in which fatty deposits clog your arteries. Measuring CRP alone won't tell your doctor your risk of heart disease. But factoring in CRP test results with other blood test results and risk factors for heart disease helps create an overall picture of your heart health.

According to the American Heart Association, your CRP test result can be interpreted as putting your heart disease risk at:

  • Low risk (less than 1.0 milligrams per liter, or mg/L)
  • Average risk (1.0 to 3.0 mg/L)
  • High risk (above 3.0 mg/L)

The American Heart Association doesn't yet recommend CRP screening for the general public — only those at known risk of heart disease.

Cholesterol-lowering statin medications may reduce CRP levels and decrease your heart disease risk, but it's not recommended that you take statin medications solely to decrease your CRP level. Talk to your doctor if you're concerned about your CRP level.



Fibrinogen is a protein in your blood that helps blood clot. But too much fibrinogen can cause a clot to form in an artery, leading to a heart attack or stroke.

Having too much fibrinogen may also mean that you have atherosclerosis. It may also worsen existing injury to artery walls.

Your doctor may check your fibrinogen level if you have an increased risk of heart disease. Smoking, inactivity, drinking too much alcohol and taking supplemental estrogen — whether from birth control pills or hormone therapy — may increase your fibrinogen level.

A normal fibrinogen level is considered to be between 200 and 400 mg/L.



Homocysteine is a substance your body uses to make protein and to build and maintain tissue. But too much homocysteine may increase your risk of stroke, certain types of heart disease, and disease of the blood vessels of the arms, legs and feet (peripheral artery disease).

Your doctor may check your homocysteine level if you've had cardiovascular problems but don't have any of the traditional risk factors, such as smoking. Your doctor may also suggest screening if any family members developed heart problems at a young age or have high homocysteine levels. A normal homocysteine level is between 4.4 and 10.8 micromoles per liter (µmol/L).

Your homocysteine level may drop if you get plenty of folate (folic acid) and B vitamins in your diet through foods such as green, leafy vegetables and fortified grain products or through supplements.

But it's not known if reducing your homocysteine level actually reduces your risk of death from heart disease.

Jun. 01, 2011 See more In-depth