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Ketones - urine
Definition
Ketones build up when the body needs to break down fats and fatty acids to use as fuel. This is most likely to occur when the body does not get enough sugar or carbohydrates.
A urine test can be done to check the level of ketones in your body.
Alternative Names
Ketone bodies - urine; Urine ketones
How the Test is Performed
The test requires a clean catch urine sample.
To obtain a clean catch sample, men or boys should clean the head of the penis. Women or girls need to wash the area between the lips of the vagina with soapy water and rinse well.
As you start to urinate, allow a small amount to fall into the toilet bowl to clear the urethra of contaminants. Then, put a clean container under your urine stream and catch 1 to 2 ounces of urine. Remove the container from the urine stream. Cap and mark the container and give it to the health care provider or assistant.
For infants, thoroughly wash the area around the urethra. Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on the infant. For boys, the entire penis can be placed in the bag and the adhesive attached to the skin. For girls, the bag is placed over the labia. Diaper as usual over the secured bag.
This procedure may take a couple of attempts -- lively infants can displace the bag. The infant should be checked frequently and the bag changed after the infant has urinated into the bag. The urine is drained into the container for transport to the laboratory.
Urine ketones are usually measured as a "spot test" using a dipstick coated with chemicals that react with ketone bodies. The dipstick is dipped in the urine sample, and a color change indicates the presence of ketones.
How to Prepare for the Test
You may have to eat a special diet, and you should stop taking any drugs that may affect the test.
If the collection is being taken from an infant, you may need extra collection bags.
How the Test Will Feel
The test involves only normal urination, and there is no discomfort.
Why the Test is Performed
Ketone testing is most often done if you have type 1 diabetes and:
- Your blood sugar is higher than 240 mg/dL
- You have an illness such as pneumonia, heart attack, or stroke
- Nausea or vomiting occur
- You are pregnant
Normal Results
A negative test result is normal.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
An abnormal result means you have ketones in your urine. The results are usually listed as small, moderate, or large as follows:
- Small: < 20 mg/dL
- Moderate: 30 - 40 mg/dL
- Large: > 80 mg/dL
This may be due to diabetic ketoacidosis, a problem that occurs in people with Type 1 diabetes. It occurs when the body cannot use sugar (glucose) as a fuel source because there is little or no insulin. Fat is used for fuel instead.
An abnormal result may also be due to:
- Abnormal food or nutrition intake due to:
- Anorexia
- Fasting
- High protein or low carbohydrate diets
- Starvation
- Vomiting over a long period of time
- Disorders of increased metabolism
- Acute or severe illness
- Burns
- Fever
- Hyperthyroidism
- Nursing a baby (lactation)
- Pregnancy
Risks
There are no risks.
Considerations
Special diets can change test results. For example, a diet low in carbohydrates and high in protein and fat can raise ketone levels in the blood, which can then enter the urine.
Some drugs, including glucocorticoids, can cause false positive measurements.
References
Inzucchi SE, Sherwin RS. Type 1 diabetes mellitus. In: Goldman L, Ausiello D, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 247.
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
