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Ketone Testing

What are ketones?

Ketones are chemicals that appear in the blood and urine when your body burns fat for energy. Your body burns fat when there is not enough insulin to allow sugar to be burned for energy. Ketones also are produced when you have not eaten enough food to provide the energy your body needs.

Why do I need to test for ketones?

When you have type 1 diabetes, ketone testing is very important because ketones can build up in the body. The buildup can cause an emergency condition called ketoacidosis. Ketoacidosis is a serious, life-threatening problem and must be treated immediately.

Frequent ketone tests can be important in the first few days after you are first diagnosed with type 1 diabetes. You need to make sure that you are taking enough insulin to turn off ketone production.

The presence of urine ketones can be altered by some medicines. Make sure your doctor knows all the medicines you are taking.

When should I test for ketones?

If you have just been recently diagnosed with type 1 diabetes, you may need to check ketones routinely twice a day. If a ketone test is positive, you may need to test more often than this. If all of your ketone tests are negative after 1 or 2 weeks of testing, you may be able to stop routine testing of ketones.

Follow your healthcare provider’s recommendations for reporting positive ketone test results. This is a very important part of getting your diabetes under control and regulating your insulin.

If you are taking insulin and have just 1 insulin shot a day, your healthcare provider may ask you to do a ketone test every morning to see if the effect of the insulin is lasting a full 24 hours. Ketones will usually be present in the morning if you need more insulin.

If your morning blood sugars vary between very high and very low values, check your ketone level in the morning. Morning ketones can be a sign of a low blood sugar during the night. Your blood sugar may bounce back to a normal or high level by the time you check it in the morning, but low blood sugar during the night can be dangerous. Sometimes checking for morning ketones helps diagnose the problem of nighttime low blood sugar.

Your provider may recommend that you also check for ketones if:

  • Your blood sugar level is higher than 240 mg/dL (about 13 mmol/dL).
  • You are ill or under more stress than usual. When you are sick, you can have ketones even if your blood sugar is not high. This is especially true if you are not able to eat and your body is burning fat for energy.

Ask your healthcare provider when you should check for ketones and be sure to follow his or her recommendations. This is especially important if you are pregnant and have diabetes.

A method of testing for ketones must be kept in the home (and taken on trips) at all times in case you get sick or have had recent changes in your medicines.

How do I test for ketones?

Tests for checking ketones are available at your local pharmacy. You can check for ketones in the urine or in the blood. Record the test results in a notebook so you don't forget them.

Urine Tests

To check for urine ketones you can use urine test strips. Some commonly used strips are Ketostix or Chemstrip K. The strips are good for about 6 months once a bottle of strips is opened. Strips that are individually wrapped last 2 to 3 years. Ask your pharmacist about the types of urine ketone strips available.

Follow the package directions for testing carefully. Urine ketone tests must be timed exactly using a watch or clock with a secondhand. After you dip the strip in the urine sample, compare the color of your test strip with the colors in the chart on the container. Ask someone else to watch the timing of the test with you and to check your reading of the strip. This helps prevent errors due to color blindness or other factors.

Blood Tests

To check for ketones in the blood you need a meter and blood ketone strips. Your provider can show you how to use the meter for measuring blood ketones.

The blood ketone measurement gives you the value at that moment. The urine ketones may reflect levels from a few hours earlier.

When should I call my healthcare provider?

Call your provider right away (day or night) if:

  • The urine ketone test shows moderate or large levels of urine ketones.
  • The blood ketone test result is higher than 1.0 mmol/L.

If the urine ketone test result is large or the blood test is above 1.0 mmol/L, tell the person answering your call that the call is urgent.

Call during office hours if:

  • You are concerned about the test result.
  • You have other questions or concerns.
Originally abstracted from the book, "Understanding Diabetes," 10th ed., by H. Peter Chase, MD (available by calling 800-695-2873).
Published by RelayHealth.
Last modified: 2011-05-16
Last reviewed: 2011-03-03
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 healthcare professional.
© 2011 RelayHealth and/or its affiliates. All rights reserved.
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