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Urinalysis    See images

Overview | Risks | Results

Alternative names:

Urine appearance and color; Routine urine test

Definition:

A urinalysis is an examination of the urine by physical or chemical means. Urinalysis comprises a battery of chemical and microscopic tests that help to screen for urinary tract infections, renal disease, and diseases of other organs that result in abnormal metabolites (break-down products) appearing in the urine.

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.

The tests should be performed within 15 minutes after the urine is collected. Various tests can be conducted from the sample. Most of the screening urinalysis tests are measured by a reagent "dipstick" which contains little pads of chemicals that change color when they come in contact with the substances of interest. There are several types of reagent strips, and it depends on the type of strip as to what tests can be performed.

The urine can also be analyzed in the laboratory.

Gross and chemical exam (see also urine chemistry):

• Urine appearance and color (for example, clear, cloudy, turbid, layered; pale yellow, dark yellow, red, green, blue)
• Bilirubin - urine (a degradation product of hemoglobin)
• Glucose (a sugar) -- see glucose - urine
• Hemoglobin (an indication of hemolysis)
• Urine ketones (a by-product of fat metabolism and present in starvation and diabetes)
• Nitrite (an indication of urinary tract infection)
• Urine pH (the acidity or alkalinity of the urine)
• Urine protein
• Urine specific gravity (that is, how concentrated or dilute the urine is)
• Urobilinogen (a degradation product of bilirubin)

Microscopic exam:

• Bacteria and other microorganisms (not normally present) or see urine culture (clean catch)
• Casts 
• Crystals
• Fat
• Mucous
• Red blood cells (an indication of damage to the tubules)
• Renal tubular cells
• Transitional epithelial cells
• White blood cells (an indication of urinary tract infection)

How to Prepare for the Test

Collect a urine sample. The first morning urine is the most concentrated, and it is more likely to show abnormalities. Some drugs and medications can affect the test. These will be monitored or 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

This may be done as a general screening to check for early signs of disease. It may also be used to monitor diabetes or kidney disease. It may be used to check for a urinary tract infection or blood in the urine.

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