Do I Need to Fast Before a Cholesterol Test? And Other Common Questions About Cholesterol

High cholesterol is often called a “silent” condition, with many people experiencing no symptoms until they have serious heart problems. In the United States, about 86 million adults have high cholesterol levels, but only two thirds of Americans have had their numbers checked in the last five years, according to the Centers for Disease Control and Prevention.

“It’s important to know your cholesterol levels,” says Dr. Samuel Kim, a preventive cardiologist specializing in lipidology at NewYork-Presbyterian/Weill Cornell Medical Center. “They are an indicator of your heart health and if your numbers are high, there are steps you can take to reduce cardiovascular risk.”

The American Heart Association recommends that all adults 20 or older have their cholesterol checked every four to six years as long as their risk remains low. After age 40, your provider will also calculate your 10-year risk of having a heart attack or stroke.

Health Matters spoke with Dr. Kim, who is also an assistant professor of medicine at Weill Cornell Medicine, to better understand cholesterol screening and how to prepare for a test.

What is cholesterol, and what happens when it’s high?

Cholesterol is a waxy substance essential for making hormones, vitamins, and cells in your body. It can be obtained through diet or produced by your liver.

Cholesterol isn’t bad, but in excess can put you at risk for plaque formation in your heart’s arteries or the carotid artery in your neck. It can also cause inflammation and damage to the lining of the blood vessel, increasing the risk of heart attack and stroke.

What causes high cholesterol?

Genetic mutations, certain medications, and diet can be causes. A fairly common genetic mutation is what is called familial hypercholesterolemia, which affects about 1 in 200 to 250 people. Knowing your family history is important to reduce risk.

With diet, it’s key to be mindful of what you’re eating day to day. For example, following a diet with a lot of red meat will increase low-density lipoprotein (LDL) cholesterol.

When do you need a cholesterol test?

Everyone should get a cholesterol panel at least once every 5 years, but more frequent checks are recommended for people who are at risk for heart disease or who have made changes in their medication or lifestyle.

How is a cholesterol test done? Do I need to fast before a cholesterol test?

A cholesterol test is a simple blood test done in a single tube and testing results usually come back within 24 hours. For most people, fasting is not required, and you can drink coffee, water, and take your usual medications.

The exception is if you have very high triglycerides, then it may be worth getting it done fasting for more accurate testing. Ask your doctor for their recommendation.

In addition to the traditional cholesterol panel, there is an increased awareness for including lipoprotein(a) as an additional cholesterol risk marker. Lipoprotein(a) is a separate cholesterol marker (mostly genetically determined) that can further increase the risk of heart disease. Currently, there are no definitive treatment for lipoprotein(a) at this time, but multiple promising therapeutics are currently in clinical trial.

What do the test results mean?

Low-density lipoprotein (LDL) is known as the “bad cholesterol.” That’s the leftover cholesterol after your body has processed it. These are particularly at risk of building plaque. Major offenders that influence your LDL include saturated fats like butter, processed foods, and red meat.

High-density lipoprotein (HDL) is “good cholesterol” and helps remove other forms of cholesterol from your blood. It’s probably the least understood cholesterol in its functionality and remains an area of research. We know that people who lose weight and exercise increase their HDL, but people who over-consume alcohol also have high HDL.

Triglycerides are the most common type of fat in the blood, and a function of your carbohydrate and sugar intake. The levels correlate with the risk of developing diabetes. Triglycerides are impacted by foods like bread, pizza, white rice, and pasta.

How is high cholesterol treated?

More than any medication, I emphasize small dietary changes early on, such as replacing a high-carb or high-sugar item with a vegetable snack or drinking water instead of soda. The goal is to sustain healthy numbers over decades of time.

If patients need more aggressive treatment, there are therapeutics such as injectable medications and other oral pills. Statins, or medications that work in the liver, are generally taken once a day and lower LDL.