According to the May 2001 National Cholesterol Education Program guidelines, a fasting blood cholesterol test is the best way to tell for sure whether you have high cholesterol. This test requires a little bit of preparation from you, but it is more accurate in predicting your risk for heart disease.
How Do I Prepare for the Test?
You need to fast for 9 to 12 hours before the test. That means you may not eat during this time, and you may drink only water, or coffee or tea with no cream, milk, or sugar. The following may affect your results:
- illness or pregnancy
- recent injury or surgery
- recent major change in your diet
If any of these applies to you, your doctor will want to reschedule your test for another time. In addition, if you've had a recent heart attack, your cholesterol levels may be lower than usual for up to 12 weeks after the attack.
What Is the Test Like?
Your doctor will take a blood sample by drawing a vial of blood from your arm. The blood will be analyzed at a lab.
What Does the Test Measure?
HDL cholesterol, your LDL cholesterol, and your triglycerides. If you have high cholesterol, you also need fasting blood tests during your treatment to check how well it is working.
If your blood test is not done after you've fasted, then only the values for your total cholesterol and your HDL cholesterol can be used to consider your treatment. In those cases, if your total cholesterol is 200 mg/dL or higher or if your HDL is 40 mg/dL or lower, you should talk with your doctor about having a fasting cholesterol test to get more complete results.
How Often Do I Need It?
In general, healthy adults age 20 and older need a cholesterol screening at least every 5 years. You may need the test more often if you have had high cholesterol or if you have diabetes. If you take medicine to lower your cholesterol you may need more frequent tests to see how well your medicine is working. Your doctor may also recommend more frequent testing if you have had heart disease, a stroke, or peripheral vascular disease. Ask your doctor how often you need the test.