Should you fast before a cholesterol test?

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Should you fast before a cholesterol test?

A doctor may instruct a person to fast before taking a cholesterol test. This was once standard practice, but new studies are changing this recommendation.

A cholesterol test measures the amount of cholesterol and triglycerides in a person’s blood. Cholesterol is a fat-like material that is present in all of the body’s cells.

The body needs some cholesterol to help produce vitamin D, hormones, and enzymes that aid digestion.

A cholesterol test, also known as a lipids panel, measures several different types of cholesterol, including:

  • high-density lipoprotein (HDL) cholesterol, or “good cholesterol”
  • low-density lipoprotein (LDL) cholesterol, or “bad cholesterol”
  • triglycerides, the chemical form in which most fats exist

To work out a person’s total cholesterol score, a healthcare professional adds the HDL and LDL cholesterol levels to 20 percent of the triglyceride level.

A doctor will use these results to assess a person’s risk of developing heart disease and other health problems relating to high cholesterol.

Read on to find out more about fasting before a cholesterol test.

Fasting before the test

A person will need to refrain from food and drink for 9–12 hours before a fasting cholesterol test.

Standard practice used to require a person to fast for 9–12 hours before taking a cholesterol test, meaning that they should have no food or drink other than water during that time.

However, recent guidelines have changed. They now allow doctors to recommend nonfasting cholesterol testing to certain groups of individuals.

One 2017 paper recommends nonfasting cholesterol testing, citing the following advantages of nonfasting cholesterol testing:

  • convenient
  • safe
  • no waiting required

The author also states that research involving over 300,000 people suggests that nonfasting tests are at least as accurate as fasting tests at predicting future cardiovascular health problems.

This paper suggests that the triglyceride level will rise by an average of 26 milligrams per deciliter (mg/dl) for a nonfasting reading in comparison with the fasting level. The total cholesterol and LDL cholesterol levels will be 8 mg/dl lower, on average. The authors believe that this difference is clinically insignificant.

However, the medical community continues to debate the need for some higher-risk groups to fast before testing.

According to another analysis from the American College of Cardiology, higher-risk groups may benefit from fasting. This is because the equation that doctors use to find the LDL level tends to underestimate the levels of LDL and triglycerides in people who do not fast.

Due to this, a doctor may recommend that some people fast before a cholesterol test but suggest that other individuals do not need to. A person should follow their doctor’s recommendation regarding fasting.

In cases where a doctor does recommend fasting before a cholesterol test, this often means that the person must refrain from all food and drink except water for 9–12 hours before the test.

A person who undergoes a fasting cholesterol test is likely to go for the test first thing in the morning so that they may eat after the test and do most of the fasting while they sleep.

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