Cholesterol test results can vary by as much as 10 percent, depending on what you recently ate or drank, the drugs you take, and other health problems you may have. For example, some research suggests that periods of high stress can raise your cholesterol levels.

Here's what to do—and what to avoid—to get the most accurate cholesterol test results.

Ask If You Need to Fast

Your doctor might just want to check your total cholesterol and HDL (good) cholesterol levels, which aren’t affected by eating. But if your doctor also wants to look at your LDL (bad) cholesterol levels and triglycerides (a type of fatty acid found in the blood), you’ll need to fast for about 12 hours beforehand, which means no food and no drinks other than water, says Nieca Goldberg, M.D., a cardiologist and director of the Joan H. Tisch Center for Women’s Health at the NYU Langone Medical Center.

Read our Best Buy Drugs advice on the best drugs for lowering cholesterol

Redo the Test If Results Are Abnormal

If your cholesterol levels are unusually high or low, your doctor should repeat the test a few weeks later. “Stress can raise cholesterol, but other conditions, including cancer, can dramatically lower it,” Goldberg says. If it’s still high, ask your doctor about lifestyle measures or medication to reduce it. If it’s low, your doctor may want to run tests to rule out other health problems.

Avoid Intense Workouts

Don't do an intense workout before a cholesterol test. Some research suggests that exercising strenuously 12 to 24 hours before the test could falsely elevate your HDL.

Be Savvy About Home Tests

Testing cholesterol levels at home might be useful, especially if you are on a cholesterol-­lowering drug. But you shouldn’t need to test more frequently than every six months, and if you do test at home, look for one that breaks down cholesterol into LDL, HDL, and triglycerides.

Make Sure Your Doctor Knows All of Your Meds

Drugs such as birth control pills, hormone replacement therapy, steroids, and blood pressure medication such as beta-blockers and diuretics can raise cholesterol levels and affect cholesterol test results. “We’re not usually going to recommend people go off of these drugs, since they need them, but it will help us make a more accurate interpretation of the results,” Goldberg says.