A simple guide to cholesterol testing

Everyone 20 years old and older should have a cholesterol test at least every five years. If you have a family history of heart disease or other risk factors, your doctor may test you more often.

A cholesterol test, also known as a lipid panel or lipid profile, measures how many milligrams of this fat-like substance are contained in one decilitre of blood, which is slightly less than 125 millilitres (half a cup).

• The standard test checks your level of total cholesterol as well as LDL ("bad") and HDL ("good") cholesterol levels.
• It also measures triglycerides, another type of potentially dangerous blood fat.
• For accurate results, you should fast for nine to 12 hours before a cholesterol test.
• Failure to do so is the most common cause of skewed results (if your test shows that you have elevated cholesterol and triglycerides, your doctor will probably repeat it).

Patients whose cholesterol levels place them in the danger zone (over 240 milligrams per decilitre) usually receive a prescription for a statin or other cholesterol-lowering drug.

• Studies show that these medications prevent 25 to 50 percent of heart attacks and strokes in high-risk patients.
• Doctors have many ways of judging your risk of having a heart attack and deciding how aggressively to lower it with medication.
• The cholesterol test is one.
• Another is a fancy X-ray called electron-beam computed tomography, or EBCT (also called Ultrafast CT), which reveals calcium in the arteries.
• Large deposits of this mineral increase the risk of heart attack by two or three times.
• Some research suggests that EBCT offers a more accurate picture of a patient's heart attack risk than older tests, such as the cardiac stress test (which uses an electrocardiogram to measure heart activity while a patient exercises).
• However, EBCT is expensive and exposes patients to radiation.
• It can produce false-positive results, and a negative result doesn't necessarily mean you're not at risk for a heart attack.

Do you need the scan? The answer for most people is no, though there are exceptions.

• A recent study found that women who seemed to have a low risk of cardiovascular disease yet had high calcium scores were six times more likely to have heart attacks than women with no calcium in their arteries.
• One-third to half of all heart attacks occur in people who do not have high cholesterol.
• Ask your doctor if the test is right for you.

Regardless of your age, getting your cholesterol tested is something you should think about every few years. Planning your diet and exercise routine around this can significantly decrease your health risks in the future, so why not play it safe and get it checked out.