A ketones urine test measures the presence or absence of ketones in the urine.
Ketone bodies - urine; Urine ketones: acetone, acetoacetic acid, and beta-hydroxybutyric acid
How the test is performed:
Child or adult:
Collect a clean-catch ("midstream") urine sample. To obtain a clean-catch sample, men or boys should wipe 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 (this clears the urethra of contaminants). Then, in a clean container, catch about 1 - 2 ounces of urine and remove the container from the urine stream. Give the container to the health care provider or assistant.
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 your infant. For boys, the entire penis can be placed in the bag and the adhesive attached to the skin. For girls, place the bag over the labia. Diaper the infant as usual, covering and securing the bag. Check the baby frequently and remove the bag after the infant has urinated into it. Active infants may displace the bag, so it may take more than one attempt to obtain the specimen. Drain the urine into a container and give it to the health care provider.
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:
Ketones are the end-product of rapid or excessive fatty-acid breakdown. Examples of ketones are:
- Acetoacetic acid
- Beta-hydroxybutyric acid
Ketones will be present in the urine when the ketones in the blood go above a certain level.
A number of hormones, including glucagon , epinephrine, and growth hormone can cause fatty acids to be released from body fat (adipose tissue) into the blood. The levels of these hormones increase in starvation (whether related to excess alcohol use or not), uncontrolled diabetes , and a number of other conditions.
A negative test result is normal. When ketones are present in the urine, the results are usually listed as small, moderate, or large with these corresponding values:
Small: < 20 mg/dL
Moderate: 30 - 40 mg/dL
Large: > 80 mg/dL
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results mean:
A positive test may indicate:
- Abnormal nutritional conditions
- High protein or low carbohydrate diets
- Disorders of increased metabolism
- Acute or severe illness
- Nursing a baby (lactation)
- Post-surgical condition
- Metabolic abnormalities, including uncontrolled diabetes or glycogen storage disease
- Vomiting frequently over a long period of time
What the risks are:
There are no risks.
Special diets can change test results. For example, a diet low in carbohydrates and high in protein and fat can affect ketone levels.
Some drugs, including glucocorticoids, can cause false positive measurements.