Blood tests for heart disease

The blood can give many clues about heart health. For one, high levels of "bad" cholesterol in the blood can be a sign of higher risk of having a heart attack. And other substances in the blood can point to heart failure or the risk of getting fatty deposits, called plaques, in the arteries. This is called atherosclerosis.

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

Here's a look at some of the blood tests used to diagnose and manage heart disease.

Cholesterol test

A cholesterol test, also called a lipid panel or lipid profile, measures the fats in the blood. The results can show the risk of having a heart attack or other heart disease. The test most often measures:

• Total cholesterol. This is the amount of the blood's cholesterol content. A high level can raise the risk of heart disease.

  It's best if the total cholesterol level is lower than 200 milligrams per deciliter (mg/dL) or 5.2 millimoles per liter (mmol/L).

• Low-density lipoprotein (LDL) cholesterol. This is sometimes called the "bad" cholesterol. Too much LDL cholesterol in the blood causes plaque to build up in the arteries. The buildup cuts blood flow and leads to heart and blood vessel conditions.

  The LDL cholesterol level should be less than 130 mg/dL (3.4 mmol/L). But the lower the better. It's best if levels are under 100 mg/dL (2.6 mmol/L).

  This is especially true for people with diabetes or a history of heart attack, a heart stent, heart bypass surgery, or other heart or vascular condition. In people with the highest risk of heart attacks, the LDL level to aim for is below 70 mg/dL (1.8 mmol/L).

• High-density lipoprotein (HDL) cholesterol. This is sometimes called the "good" cholesterol because it helps carry away LDL ("bad") cholesterol from the arteries. This keeps the arteries open and blood flowing more freely.

  Men should aim for an HDL cholesterol level over 40 mg/dL (1.0 mmol/L). Women should aim for an HDL over 50 mg/dL (1.3 mmol/L). The higher the better.

• Triglycerides. Triglycerides are another type of fat in the blood. High levels can increase the risk of heart disease.

  The triglyceride level should be less than 150 mg/dL (1.7 mmol/L).

• Non-HDL cholesterol. Total cholesterol minus HDL cholesterol equals non-high density lipoprotein cholesterol (non-HDL-C). Non-HDL-C is involved in plaque buildup in the arteries. Non-HDL-C fraction may be a better marker of risk than total cholesterol or LDL cholesterol.

High-sensitivity C-reactive protein

The liver makes C-reactive protein (CRP) as part of the body's response to injury or infection. The response causes swelling inside the body, called inflammation.

Inflammation plays a major role in the buildup of plaques in the arteries, called atherosclerosis. High-sensitivity CRP (hs-CRP) tests help show the risk of heart disease before there are symptoms. Higher hs-CRP levels are linked to a higher risk of heart attack, stroke and heart disease.

Many things such as having a cold or going for a long run can cause CRP levels to rise briefly. So the test should be done twice, two weeks apart. An hs-CRP level above 2.0 milligrams per liter (mg/L) shows a higher risk of heart disease.

Lipoprotein (a)

Lipoprotein (a), or Lp(a), is a type of LDL cholesterol. Genes affect Lp(a) level. Lifestyle does not.

High levels of Lp(a) may show a higher risk of heart disease. But it's not clear how much risk. Your health care professional might order an Lp(a) test if you have atherosclerosis or heart disease but seem to have healthy cholesterol levels. Or you might have the test if you have a family history of early-onset heart disease, sudden death or stroke.

Drugs are being made to lower Lp(a). But it isn't yet clear what lowering Lp(a) will do for heart disease risk.

Plasma ceramides

This test measures the levels of ceramides in the blood. All cells make ceramides. They play a big role in the way many types of tissue grow, work and die. Ceramides are linked to atherosclerosis.

Three ceramides have been linked to plaque buildup in the arteries and insulin resistance, which can lead to type 2 diabetes. High levels of these ceramides in the blood are a sign of a higher risk of getting heart disease in 1 to 5 years.

Natriuretic peptides

Brain natriuretic peptide is a protein the heart and blood vessels make. It's also called B-type natriuretic peptide (BNP). BNP helps the body get rid of fluids, relaxes blood vessels and moves sodium into the urine.

With heart damage, the body puts high levels of BNP into the blood to try to ease the strain on the heart. One important use of BNP is to try to learn whether shortness of breath is due to heart failure.

BNP levels vary by age, gender and weight. For people who have heart failure, getting a baseline BNP can be helpful. Future tests might help measure how well treatment works.

Troponin T

Troponin T is a protein found in heart muscle. A high-sensitivity troponin T test helps health care professionals diagnose a heart attack. The test also shows the risk of heart disease. An increased level of troponin T has been linked with a higher risk of heart disease in people who have no symptoms.