Urine is produced by the kidneys, two fist-sized organs located on either side of the spine at the bottom of the ribcage. The kidneys filter wastes out of the blood, help regulate the amount of water in the body, and conserve proteins, electrolytes, and other compounds that the body can reuse. Anything that is not needed is eliminated in the urine, traveling from the kidneys through ureters to the bladder and then through the urethra and out of the body. Urine is generally yellow and relatively clear, but each time a person urinates, the color, quantity, concentration, and content of the urine will be slightly different because of varying constituents.
Many disorders may be detected in their early stages by identifying substances that are not normally present in the urine and/or by measuring abnormal levels of certain substances. Some examples include glucose, protein, bilirubin, red blood cells, white blood cells, crystals, and bacteria. They may be present because:
- There is an elevated level of the substance in the blood and the body responds by trying to eliminate the excess in the urine.
- Kidney disease is present.
- There is a urinary tract infection present, as in the case of bacteria and white blood cells.
A urinalysis is a test of your urine. A urinalysis is used to detect and manage a wide range of disorders, such as urinary tract infections, kidney disease and diabetes.
For example, a urinary tract infection can make urine look cloudy instead of clear. Increased levels of protein in urine can be a sign of kidney disease. Unusual urinalysis results often require more testing to uncover the source of the problem.
Why is it done
A urinalysis is a common test that's done for several reasons:
- To check your overall health. For example, to screen for a variety of disorders, such as diabetes, kidney disease and liver disease.
- To diagnose a medical condition. For example, if you're experiencing abdominal pain, back pain, frequent or painful urination, blood in your urine, or other urinary problems. A urinalysis may help diagnose the cause of these symptoms.
- To monitor a medical condition. If you've been diagnosed with a medical condition, such as kidney disease or a urinary tract disease, you may do a urinalysis on a regular basis to monitor your condition and treatment.
How you prepare
If your urine is being tested for a urinalysis, you can eat and drink normally before the test.
Many drugs, including nonprescription medications and supplements, can affect the results of a urinalysis. Before a urinalysis, try to refrain from any medications, vitamins or other supplements you're taking.
Urinalysis Reagent Strips
Urine dipstick is a narrow plastic strip which has several squares of different colors attached to it. Each small square represents a component of the test used to interpret urinalysis. The entire test strip is dipped in the urine sample and color changes in each square are noted. The color change takes place after several seconds to a few minutes from dipping the strip. If read too early or too long after the urinalysis strip is dipped, the results may not be accurate.
Each color change on a particular square may indicate specific abnormalities in the urine sample caused by a certain chemical reaction. The reference for color changes is posted on the plastic bottle container of the urine test strips. This makes for easy and quick interpretation of the urinalysis results by placing the strip next to the container and comparing its color changes to the reference provided.
The squares on the dipstick represent the following components in the urine:
- specific gravity (concentration of urine),
- acidity of the urine (pH),
- protein in the urine (mainly albumin),
- glucose in the urine (sugar),
- ketones (products of fat metabolism),
- blood in the urine,
- leukocyte esterase (suggestive of white blood cells in urine),
- nitrite (suggestive of bacteria in urine),
- bilirubin (possible liver disease or red blood cell breakdown), and
- urobilinogen (possible liver disease).
Presence or absence of each of these color changes on the strip provides important information for clinical decisions.
After the UA test strip is dipped in urine briefly and completely, the reading is done within a few minutes. Each one of the squares on the box has next to it the time which is recommended for its interpretation (for example, whether these is a change in color on the square). The squares are placed in similar order on the box, from the ones requiring the shortest time to read of 30 seconds to the ones with the longest time to read of two minutes. This arrangement is based on result time and makes it easier to quickly read and interpret any color changes by simply scanning the strip from the shortest (glucose) to the longest (leukocytes).
What does the test result mean?
Urinalysis results can have many interpretations. Abnormal findings are a warning that something may be wrong and should be evaluated further. A healthcare practitioner must correlate the urinalysis results with a person's symptoms and clinical findings and search for the causes of abnormal findings with other targeted tests.
Generally, the greater the concentration of the atypical substance, such as greatly increased amounts of glucose, protein, or red blood cells, the more likely it is that there is a problem that needs to be addressed. However, the results do not tell the healthcare practitioner exactly what the cause of the finding is or whether it is a temporary or chronic condition.
A normal urinalysis does not guarantee that there is no illness. Some people will not release elevated amounts of a substance early in a disease process, and some will release them sporadically during the day, which means that they may be missed by a single urine sample. In very dilute urine, small quantities of chemicals may be undetectable.