Blood tests for heart disease

Your blood may offer 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 health care provider determine if you have heart failure or are at risk of developing fatty deposits (plaques) in your arteries (atherosclerosis).

It's important to remember that one blood test alone doesn't determine the risk of heart disease. The most important 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 measurements can help determine the risk of having a heart attack or other heart disease. The test typically includes measurements of:

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

  Ideally, the total cholesterol level should be below 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 buildup in the arteries, which reduces blood flow. These plaque deposits sometimes rupture and lead to major heart and blood vessel problems.

  The LDL cholesterol level should be less than 130 mg/dL (3.4 mmol/L). Desirable levels are under 100 mg/dL (2.6 mmol/L), especially if you have 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 recommended LDL level 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, keeping 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).

• Triglycerides. Triglycerides are another type of fat in the blood. High triglyceride levels usually mean you regularly eat more calories than you burn. High levels can increase the risk of heart disease.

  The recommended triglyceride level is less than 150 mg/dL (1.7 mmol/L).

• Non-HDL cholesterol. Non-high density lipoprotein cholesterol (non-HDL-C) is the difference between total cholesterol and HDL cholesterol. Non-HDL-C includes cholesterol in lipoprotein particles that are involved in hardening of the arteries. Non-HDL-C fraction may be a better marker of risk than total cholesterol or LDL cholesterol.

High-sensitivity C-reactive protein

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

Inflammation plays a major role in the process of atherosclerosis. High-sensitivity CRP (hs-CRP) tests help determine the risk of heart disease before symptoms are present. Higher hs-CRP levels are associated with a higher risk of heart attack, stroke and cardiovascular disease.

Because CRP levels can be temporarily increased by many situations such as a cold or going for a long run, the test should be done twice, two weeks apart. An hs-CRP level above 2.0 milligrams per liter (mg/L) indicates a higher risk of heart disease.

Combining your hs-CRP test and other blood test results with your heart disease risk factors gives your health care provider a picture of your overall heart health. Your health care provider will determine if you may benefit from having your hs-CRP measured to better estimate your risk of heart attacks or stroke.

Cholesterol-lowering statin medications may reduce CRP levels and decrease heart disease risk.

Lipoprotein (a)

Lipoprotein (a), or Lp(a), is a type of LDL cholesterol. Your Lp(a) level is determined by your genes and isn't generally affected by lifestyle.

High levels of Lp(a) may be a sign of increased risk of heart disease, though it's not clear how much risk. Your health care provider might order an Lp(a) test if you already have atherosclerosis or heart disease but appear to have otherwise healthy cholesterol levels or if you have a family history of early-onset heart disease, sudden death or stroke.

Drugs are in development to lower Lp(a), but it isn't yet clear what effect lowering Lp(a) will have on heart disease risk.

Plasma ceramides

This test measures the levels of ceramides in the blood. Ceramides are produced by all cells and play a significant role in the growth, function and ultimately death of many types of tissue. Ceramides are transported through the blood by lipoproteins and are associated with atherosclerosis.

Three specific 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 cardiovascular disease within one to five years.

Natriuretic peptides

Brain natriuretic peptide, also called B-type natriuretic peptide (BNP), is a protein that the heart and blood vessels make. BNP helps the body eliminate fluids, relaxes blood vessels and moves sodium into the urine.

When the heart is damaged, the body secretes high levels of BNP into the bloodstream to try to ease the strain on the heart. One of the most important uses of BNP is to try to determine whether shortness of breath is due to heart failure.

BNP levels vary according to age, gender and weight. For people who have heart failure, establishing a baseline BNP can be helpful and future tests can be used to help measure how well treatment works.

A variation of BNP called N-terminal BNP is also useful for diagnosing heart failure and for evaluating the risk of a heart attack and other problems in those with existing heart disease.

A high level of BNP alone isn't enough to diagnose a heart problem. Your health care provider will also consider your risk factors and other blood test results.

Troponin T

Troponin T is a protein found in heart muscle. Measuring troponin T using a high-sensitivity troponin T test helps health care providers diagnose a heart attack and determine 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.