Urine reducing substances
This is a screening test to detect various substances in the urine that chemically react with an indicator metallic dye called cupric sulfate. The most common reducing substances examined include glucose or galactose.
How the test is performed
Collect a “clean-catch” (midstream) urine sample. To do so, men and boys should wipe clean the head of the penis. Women and 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.
For an 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.
A Clinitest tablet is placed in a sample of the urine. If urinary reducing substances (glucose, galactose, or other reducing substances) are present, the urine will turn blue.
How to prepare for the test
No special preparation is necessary for this test. 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.
Why the test is performed
This test is a quick and inexpensive way of screening for diabetes and inborn metabolic problems such as galactosemia (elevated level of galactose in the blood).
Normally neither glucose nor galactose are found in the urine. Therefore, a Clinitest tablet would not turn the urine blue.
What abnormal results mean
If a reducing agent is present, then the Clinitest tablet will turn orange then brown or greenish brown. The color it changes depends on the percentage of reducing agent present. One urinary reducing substance that could be present is glucose (as seen in diabetes). A simple urine dipstick test that is specific for glucose can be performed.
If the dipstick test is positive, then you have a high level of glucose in the blood, and the glucose is spilling over into the urine. Further testing will be done to confirm or rule out diabetes.
If the Clinitest tablet turns colors as described above and the dipstick indicates that no glucose is present, then you have a high level of another reducing substance, such as galactose, in the blood, which is spilling over into the urine. Further testing will be performed to confirm or rule out galactosemia.
What the risks are
If the sample is being collected from your infant, some skin irritation may result from the adhesive on the container.
Drugs that may increase urine glucose measurements include aminosalicylic acid, cephalosporins, chloral hydrate, chloramphenicol, dextrothyroxine, diazoxide, diuretics (loop and thiazides), estrogens, isoniazid, levodopa, lithium, nafcillin, nalidixic acid, and Nicotinic Acid (large doses).
Drugs that may give false positive results with Clinitest, but not with the dipstick tests, include acetylsalicylic acid, aminosalicylic acid, ascorbic acid, cephalothin, chloral hydrate, nitrofurantoin, streptomycin, and sulfonamides.
Drugs that may give false negative results are ascorbic acid (dipstick tests such as Clinistix, Tes-tape), levodopa (Clinistix), and phenothiazines (Clinistix, Tes-tape).
by Sharon M. Smith, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.