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 carbohydrate 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.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
How It Is Done
Blood test by a laboratory
The health professional taking a sample of your blood will:
- Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
- Clean the needle site with alcohol.
- Put the needle into the vein. More than one needle stick may be needed.
- Attach a tube to the needle to fill it with blood.
- Remove the band from your arm when enough blood is collected.
- Apply a gauze pad or cotton ball over the needle site as the needle is removed.
- Apply pressure to the site and then a bandage.
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.
- 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.