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.

Your doctor may check your fibrinogen level if you have an increased risk of heart disease. Certain factors, such as smoking and taking supplemental estrogen — whether from birth control pills or hormone therapy — may increase your fibrinogen level.

This test isn't always ordered because there aren't any direct treatments to lower fibrinogen levels, and the test isn't yet standardized from lab to lab.

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.

Lp(a) is often tested if you have a family history of early-onset heart disease or sudden death in the absence of traditional risk factors. It should also be tested if your LDL cholesterol doesn't respond well to drug treatment.

Natriuretic peptides

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

When your heart is damaged, your body secretes high levels of BNP into your bloodstream to try to ease the strain on your heart. BNP levels may also rise if you have new or increasing chest pain (unstable angina) or after a heart attack.

Your BNP level can help in the diagnosis and evaluation of heart failure and other heart conditions. Normal levels vary according to age and gender. One of the most important uses of BNP is to try to sort out whether shortness of breath is due to heart failure. For people who have heart failure, establishing a baseline BNP can be helpful and future tests can be used to help gauge how well your treatment works.

A variation of BNP called N-terminal BNP also is useful in diagnosing heart failure and in some laboratories is used instead of BNP. N-terminal BNP may also be useful in evaluating your risk of heart attack and other problems if you already have heart disease.

A high level of BNP alone isn't enough to diagnose a heart problem. Your doctor will also consider your risk factors and other blood test results. This test isn't recommended for people without heart disease symptoms.

June 05, 2014 See more In-depth