Measuring Cholesterol and Triglyceride Levels

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Blood lipid levels (specifically, cholesterol and triglyceride levels) have been strongly correlated with a person’s risk of developing coronary artery disease (CAD) and other types of cardiovascular disease. Experts now recommend everyone should have blood testing for lipid levels. 

Purpose of the Test

Your blood lipid levels are a critical factor in determining your risk of cardiovascular disease, and in deciding whether you should be doing something to reduce that risk. 

Sometimes, treating abnormal lipid levels themselves (generally with statins ), can be important in lowering your cardiovascular risk. But perhaps more importantly, knowing your lipid levels is a major component of estimating your overall cardiovascular risk — and thus, of understanding how aggressive you should be in reducing your overall risk with lifestyle changes. 

Who Should Get a Triglyceride and Cholesterol Test, and When?

Current guidelines recommend that adults should be tested for cholesterol and triglyceride levels beginning at age 20, and every five years thereafter.

Children should be screened with a blood lipid test at least once before puberty, and more often if there is a family history of a blood lipid disorder, such as familial hypercholesterolemia.

If one of these routine tests show elevated cholesterol or triglyceride levels, you should have repeat blood testing, and your overall cardiac risk should be reevaluated, each year.

How Is the Triglyceride and Cholesterol Test Done?

The test for cholesterol and triglycerides consists of a simple blood test. While this is usually done by getting a blood sample with a needle and syringe, some labs routinely do lipid testing with a simple finger prick. 

Risks

As with any blood test, the risks associated with a blood lipid test are minimal. The needle stick itself can be painful, and in some people can induce a vagal response (lightheadedness, ringing in the ears, and nausea). These symptoms can usually be resolved by lying down for a few minutes and taking some fluid, and facilities that perform blood tests routinely will be well able to manage them.

A bit of bruising at the blood drawing site is normal. Larger bruises may occur in people on blood thinners, but with extra precautions even in these people excessive bruising is uncommon.

Before the Test

The only preparation required on your part is to refrain from eating anything, and from drinking any liquids aside from water, for eight to 12 hours prior to the test. If you are on prescription medication, talk to your doctor about whether you should take your pills before the test.

Drinking water before the test is not only OK, it ought to be encouraged. Avoiding dehydration will make it easier for the phlebotomist (blood-drawing technician) to find a vein easily. 

Location. The blood test may be taken in the doctor’s office, or in a blood testing lab.

What to wear. You should wear comfortable clothing, and you should make sure your sleeves can be easily rolled up. 

What to bring. You may want to bring a snack you can eat right after the test. 

Insurance coverage. Cholesterol and triglyceride blood tests are almost always covered by health insurance. Still, to be safe it is advisable to call your insurance carrier ahead of time (whose number is on your insurance card) to make sure the testing is approved.

During the Test

The test itself should take only moments, though you should expect to spend 15-30 minutes being “processed” through the office or lab. Phebotomists are extremely adept at finding veins in virtually anyone, and in getting the blood sample quickly and (virtually) painlessly.

After the test, you may be asked to sit in the waiting room for 5-10 minutes just to be sure you don’t have a vagal reaction. That’s a good time to eat your snack. 

Interpreting the Results

What Does the Blood Test Measure?

Typically, the lipid panel gives four values:

The actual blood test directly measures total and HDL cholesterol, as well as triglycerides. From these values, an estimate of LDL cholesterol is calculated.

What Are “Desirable" Cholesterol and Triglyceride Levels?

Total cholesterol: Desirable blood levels for total cholesterol are below 200 mg/dL. Levels between 200 and 239 are considered “borderline." Levels above 240 are considered "high."

LDL cholesterol: Optimal LDL levels are less than 100 mg/dL. Near-optimal levels are between 100 and 129. Levels between 130 and 159 are considered "borderline;" levels between 160 and 189 are considered "high;" and levels of 190 and above are considered "very high."

HDL cholesterol: In general, the higher the HDL cholesterol levels the better. HDL levels below 41 mg/dL are considered too low.

Triglycerides: Desirable blood levels for triglycerides are less than 150 mg_Dl. Levels between 150 and 199 are considered "borderline high." Levels between 200 and 499 are considered "high." Triglyceride levels at 500 mg_Dl or greater are considered "very high."

Other Lipid-Related Blood Tests Your Doctor May Order

There are a few other blood tests that doctors sometimes include in assessing blood lipid levels, that may be drawn at the same time as your cholesterol and triglyceride levels. These include:

The Apo-B test: The Apo-B test is a measure of the size of the LDL cholesterol particles. Small, dense LDL are associated with a high risk of vascular disease, while larger LDL particles are thought to be less dangerous. However, in most cases, a reasonable assessment of a person’s cardiac risk can be made with routine lipid testing alone.

The lipoprotein(a) test: Lipoprotein(a), or LP(a), is a modified form of the LDL lipoprotein that is associated with a higher risk of heart disease than “normal” LDL. Lp(a) levels are thought to be genetically determined, and they cannot be reduced by any known therapy. So measuring Lp(a) is not very useful clinically, and is not done routinely.

Adding It All Up

These blood lipid tests, as important as they are, should usually not be interpreted by themselves. It is important for you and your doctor to take all your other cardiac risk factors into account, and estimate your overall risk of developing cardiovascular disease. Based on this overall risk, your doctor will be able to make informed recommendations as to whether you should take steps to bring down that risk, and what those steps should be. 

Deciding on whether you ought to be treated for high cholesterol or high triglyceride levels, whether that treatment ought to include drug therapy, and which drugs ought to be used, is not always entirely straightforward. Still, if your cardiovascular risk is elevated, aggressive treatment aimed at your lipid levels can substantially reduce your chances of having a heart attack, or even of dying prematurely. Here is more information on treating cholesterol and triglyceride levels:

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Article Sources
  • Stone NJ, Robinson JG, Lichtenstein AH, et al. 2013 ACC/AHA Guideline On The Treatment Of Blood Cholesterol To Reduce Atherosclerotic Cardiovascular Risk In Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 2014; 129:S1.