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Ketone Testing


What are ketones?

Ketones are chemicals which appear in the blood and urine when body fat is used for energy. Fat is burned by the body when there is not enough insulin to allow sugar to be burned for energy. Ketones also are formed when not enough food has been eaten to provide the energy the body needs.

Why do I need to test my child for ketones?

Ketone testing is very important because ketones can build up in the body and result in an emergency condition called ketoacidosis. Ketoacidosis is a serious, life-threatening complication of high blood sugar and must be treated immediately. Ketoacidosis is the number one reason for hospitalizing children with known diabetes in the U.S.

Families are usually taught how to do the urine ketone test on the first day their child has been diagnosed with diabetes. They may later switch to doing blood ketone checks. Frequent ketone tests are important in the first few days after diagnosis to check if enough insulin is being given to turn off ketone production.

When should I test for ketones?

A method of testing for ketones must be kept in the home (and taken on trips) at all times.

Ketones must always be checked if your child:

  • has high blood sugar above 240 mg/dl (13.3 mmol/L) after fasting
  • has high blood sugar above 300 mg/dl (16.6 mmol/L) during the day
  • feels sick or nauseated (especially if he vomits, even once). If the child is sick, ketones can be present even when the sugar is not high.

Children who have been recently diagnosed with diabetes usually need to check ketones twice a day (or more often if the test is positive). After the first or second week, if all ketone checks are negative, you can stop routine testing of ketones.

Children who take only 1 insulin injection per day should do a routine morning ketone test to check if their insulin is lasting a full 24 hours. Ketones will usually be present in the morning if an insulin injection is needed in the evening. If the morning blood sugars vary between very high and very low values, check the ketone level in the morning. Morning ketones can be a sign of a low blood sugar during the night followed by rebounding or bouncing back to a normal or high level by morning.

How do I test for ketones?

You can check for ketones in the urine or in the blood. Some health insurance companies do not pay for blood ketone strips. In this case, make sure that the urine ketone tests get done. Always record the result of the ketone test in a notebook.

Urine Tests

To check for urine ketones you can use urine test strips. The strips are only good for about 6 months once the bottle of strips is opened. There are some strips that come individually foil-wrapped that will last 2 to 3 years. Ask your pharmacist about types of ketone strips available.

If your child is not yet toilet trained, it is usually best to press a test strip firmly against the wet diaper. It is also possible to place a cotton ball in the diaper near the urinary opening. Drops of urine can then be squeezed from the cotton ball.

Follow the package directions for testing carefully. Urine ketone tests must be timed exactly using a watch or clock with a second hand. Have 2 people time and read the strip. This prevents errors due to color blindness or other factors.

Blood Tests

To check for ketones in the blood you use a meter (such as the Precision Xtra meter) and blood ketone strips. The blood ketone measurement gives you the value at that moment. The urine ketones may reflect levels from a few hours earlier. For older children, the blood ketone test is often preferred. Your provider can show you how to use the meter to measure blood ketones.

Tests for checking ketones are available at your local pharmacy.

When should I call my child's healthcare provider?

Call your diabetes care provider IMMEDIATLY (day or night) if:

  • the urine ketone test result shows medium or large urine ketones
  • the blood ketone test is greater than 1.0 mmol/L.

Tell the person answering the phone that the call is urgent.

Your provider will probably have your child take extra insulin to help make the ketones disappear. If the ketones are not detected early, particularly during illness, they will build up in the body and your child will get ketoacidosis. If you detect ketones early and treat with extra Humalog, NovoLog, or Apidra insulin, it can prevent hospitalizations for ketoacidosis.

Call your diabetes care provider during office hours if:

  • You are concerned about the test result.
  • You have other questions or concerns.

Abstracted from the book, "Understanding Diabetes," 11th Edition, by H. Peter Chase, MD (available by calling 1-800-695-2873).
Published by RelayHealth.
Last modified: 2010-05-21
Last reviewed: 2010-05-11

This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a health care professional.

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