Test Overview

A ketone test checks for ketones in your blood or urine. Ketones are substances that are made when the body breaks down fat for energy. Normally, your body gets the energy it needs from carbohydrate in your diet. But stored fat is broken down and ketones are made if your diet does not contain enough carbohydrates to supply the body with sugar (glucose) for energy or if your body can't use blood sugar (glucose) properly.

Ketones can be tested in a laboratory. Or you can test for ketones anywhere you may be by using home blood or urine tests.

Why It Is Done

A blood test analyzed by a laboratory is the most accurate method of measuring ketones. It is recommended for all people with diabetes whenever symptoms of illness are present, such as nausea, vomiting, or abdominal pain. These symptoms often happen with high blood sugar and may mean you have diabetic ketoacidosis, a potentially life-threatening condition.

Home blood or urine ketone tests:

• Monitor a person who has diabetes, especially when that person is sick.
• Monitor a person on a low-carbohydrate diet and/or high-fat diet.
• Monitor a person who is not able to eat due to anorexia or fasting, who is vomiting a lot, and/or who has diarrhea.
• Monitor a person who is sick.
• Monitor a pregnant woman who has diabetes or has developed gestational diabetes.

How To Prepare

No special preparation is needed before having this test.

How It Is Done

Blood test by a laboratory

A health professional uses a needle to take a blood sample, usually from an arm.

Blood test at home

Some home blood sugar meters can also measure blood ketones. You use the same finger-prick method that you use to measure blood sugar.

Urine test

• Collect a urine sample in a clean container.
• Follow the manufacturer's directions on the bottle of test strips or tablets.
• Avoid getting toilet paper, pubic hair, stool, menstrual blood, or other foreign matter in the urine sample.

How It Feels

Blood test by a laboratory

You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Blood test at home

Your finger may feel sore after pricking it for a drop of blood for the test.

Urine test

There is normally no discomfort involved with collecting a urine sample.

Risks

Blood test by a laboratory

There is very little chance of having a problem from this test. A small bruise may form at the site. To lower the chance of bruising, keep pressure on the site for several minutes.

Blood test at home

There is very little risk of complications from testing your blood for ketones with a home blood sugar meter.

Urine test

There are no risks associated with collecting a urine sample.

Results

Blood test at home

Home blood sugar meters that also test for ketones display results on the meter's screen.

In people who have diabetes, blood ketones are expected to be lower than 0.6 mmol/L.

Urine test

Ketones are present in the urine if:

• The test strip changes colour after dipping it into the urine.
• The urine changes colour after placing the test tablet in it.

You usually compare the colour of the test strip or urine to a chart to find out if ketones are present.

High values

You may have ketones if you:

• Have poorly controlled diabetes or diabetic ketoacidosis.
• Are on a very low-carbohydrate or high-fat diet.
• Are starving or have an eating disorder, including disorders that result in poor nutrition such as anorexia nervosa or bulimia, alcohol use disorder, or poisoning from drinking rubbing alcohol (isopropanol).
• Have not eaten (fasted) for 18 hours or longer.
• Are pregnant. Some women have low levels of ketones during pregnancy and this does not affect the fetus. But a moderate or high amount of ketones in a pregnant woman may harm the fetus and may be an indication of gestational diabetes.

The level of ketones, and not just the presence of ketones, may be important to your doctor as well. Many conditions can change ketone levels. Fasting usually causes only mild increases in the level. But ketone levels in diabetic ketoacidosis are much higher. Your doctor will discuss any significant abnormal results with you in relation to your symptoms and past health.