Urinalysis is a test performed to analyze a patient's urine in order to assess overall health and to detect any possible disease conditions. It is normally administered in the doctor's office as part of comprehensive medical examination and may also be administered to diagnose the cause of a patient's symptoms.
Reasons for Urinalysis
Apart from the administration of a urinalysis during the course of a routine medical examination, the test may also be performed on patients who are pregnant, being cleared for surgery, or to monitor certain chronic diseases.
Urinalysis is used to detect various conditions and diseases, including:
- Bladder infection
- High blood pressure
- Kidney stones
- Kidney disease
- Liver disease
- Urinary tract infection
A patient's urine is typically tested when the one or more of the following symptoms are present: abdominal or back pain, frequent or painful urination, or blood in the urine.
The Urinalysis Procedure
It is important that patients follow instructions carefully when providing a urine specimen. In most cases, the patient can eat and drink normally prior to providing a urine sample, but, for some specific tests, fasting may be required.
In order to provide a midstream urine sample for urinalysis, first the urethral opening should be cleansed. Then, the patient should urinate a small amount into the toilet before providing a one to two ounce sample in the container provided. The patient can then finish urinating into the toilet.
For the clinician, the first step in urinalysis is simple observation. The urine is checked for color, odor, and clarity, any of which may provide clues to possible infection or other medical conditions. The next step in a urinalysis is testing the urine for the presence or levels of:
- Red or white blood cells
A urinalysis may also test for pH balance or for the presence of recreational drugs in the urine.
Methods of Urinalysis
There are a number of methods used to analyze the urine. In addition to the physical observation already noted, these methods include those listed below.
Dip Stick Tests
A test strip or stick is dipped into the specimen. A change in the color of the strip or stick signifies a positive or negative result.
A refractometer is an instrument used to measure the specific gravity of various substances found in the urine. This helps the doctor analyze the urine's composition.
A sample of urine is examined under a microscope to detect indications of infection, such as bacteria, white blood cells, yeast or parasites. Urine may also be examined microscopically for the presence of other substances which may indicate systemic disorders, or certain types of crystals, which may be evidence of kidney stones.
It is important that the doctor be informed of any medications, vitamins or supplements the patient is taking since these may affect test results. Some food stuffs may affect urine tests as well, such as poppy seeds often found on bagels or other baked goods.
- National Institutes of Health
- Centers for Disease Control and Prevention
- Eunice Kennedy Shriver National Institute of Child Health and Human Development
- U.S. Department of Health & Human Services
- U.S. National Library of Medicine
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