Ketones - urine

Alternative names:

acetones; ketone bodies - urine; urine ketones

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 to 2 ounces of urine and remove the container from the urine stream. Give the container to the health care provider or assistant.

Infant:
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 males, the entire penis can be placed in the bag and the adhesive attached to the skin. For females, the bag is placed over the labia. Place a diaper over the infant (bag and all). Check your baby frequently and remove the bag after the infant has urinated into it. For active infants, this procedure may take a couple of attempts--lively infants can displace the bag, causing an inability to obtain the specimen. The urine is drained into a container for transport back to the health care provider.

Urine ketones are usually measured as a "spot test" with a dipstick containing a color-sensitive pad impregnated with specific chemicals which react with ketone bodies. A color change is a qualitative indicator of the presence of ketones.

How to prepare for the test:

A special diet may be recommended, and drugs that may affect the test results should be discontinued (see Special Considerations).

If the collection is being taken from an infant, a couple of extra collection bags may be necessary.

How the test will feel:

The test involves only normal urination, and there is no discomfort.

Why the test is performed:

Ketones (beta-hydroxybutyric acid, acetoacetic acid, and acetone) are the end-product of rapid or excessive fatty acid breakdown. As with glucose, ketones "spill over" into the urine when the blood levels are above a certain threshold. Fatty acid release from adipose tissue is stimulated by a number of hormones including glucagon, epinephrine, and growth hormone. The levels of these hormones are increased in starvation, uncontrolled diabetes mellitus, and a number of other conditions.