Urinalysis
Urinalysis
Also known as: Urine test
Formally known as: Urinalysis
Related tests: Urine culture, Urine protein
At A Glance
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Why get tested?
To screen for metabolic and kidney disorders and for urinary tract infections
When to get tested?
During a routine physical or when you have symptoms of a urinary tract infection, such as abdominal pain, back pain, frequent or painful urination, or blood in the urine; as part of a pregnancy checkup, a hospital admission, or a pre-surgical work-up
Sample required?
One to two ounces of urine; first morning sample is most valuable
The Test Sample
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What is being tested?
A urinalysis is a group of tests that detect and semi-quantitatively measure various compounds that are eliminated in the urine, including the byproducts of normal and abnormal metabolism as well as cells, including bacteria, and cellular fragments. Urine is produced by the kidneys, located on either side of the spine at the bottom of the ribcage. The kidneys filter wastes and metabolic byproducts 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 excreted in the urine and travels from the kidneys to the bladder, through the urethra, and out of the body. Urine is generally yellow and relatively clear, but every time someone urinates, the color, quantity, concentration, and content of the urine will be slightly different because of varying constituents.
Many disorders can be diagnosed in their early stages by detecting abnormalities in the urine. These include increased concentrations of constituents that are not usually found in significant quantities in the urine, such as: glucose, protein, bilirubin, red blood cells, white blood cells, crystals, and bacteria. They may be present because there are elevated concentrations of the substance in the blood and the body is trying to decrease blood levels by “dumping” them in the urine, because kidney disease has made the kidneys less effective at filtering, or in the case of bacteria, due to an infection.
A complete urinalysis consists of three distinct testing phases:
physical examination, which evaluates the urine's color, clarity, and concentration;
chemical examination, which tests chemically for 9 substances that provide valuable information about health and disease; and
microscopic examination, which identifies and counts the type of cells, casts, crystals, and other components (bacteria, mucus ) that can be present in urine.
Usually, a routine urinalysis consists of the physical and the chemical examinations. These two phases can be completed in just a few minutes in the laboratory or doctor’s office. A microscopic examination is then performed if there is an abnormal finding on the physical or chemical examination, or if the doctor specifically orders it.
How is the sample collected for testing?
Urine for a urinalysis can be collected at any time. The first morning sample is the most valuable because it is more concentrated and more likely to yield abnormal results. Because of the potential to contaminate urine with bacteria and cells from the surrounding skin during collection (particularly in women), it is important to first clean the genitalia. Women should spread the labia of the vagina and clean from front to back; men should wipe the tip of the penis. As you start to urinate, let some urine fall into the toilet, then collect one to two ounces of urine in the container provided, then void the rest into the toilet. This type of collection is called a midstream collection or a clean catch.
A urine sample will only be useful for a urinalysis if it is collected as a clean catch and taken to the doctor’s office or laboratory for processing within a short period of time. If it will be longer than an hour between collection and transport time, then the urine should be refrigerated.
The Test
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How is it used?
The urinalysis is used as a screening and/or diagnostic tool because it can help detect substances or cellular material in the urine associated with different metabolic and kidney disorders. It is ordered widely and routinely to detect any abnormalities that should be followed up on. Often, substances such as protein or glucose will begin to appear in the urine before patients are aware that they may have a problem. It is used to detect urinary tract infections (UTI) and other disorders of the urinary tract. In patients with acute or chronic conditions, such as kidney disease, the urinalysis may be ordered at intervals as a rapid method to help monitor organ function, status, and response to treatment.
When is it ordered?
A routine urinalysis may be done when you are admitted to the hospital. It may also be part of a wellness exam, a new pregnancy evaluation, or a work-up for a planned surgery. A urinalysis will most likely be performed if you see your health care provider complaining of abdominal pain, back pain, painful or frequent urination, or blood in the urine, symptoms of a UTI. This test can also be useful in monitoring whether a condition is getting better or worse.
What does the test result mean?
Urinalysis results can have many interpretations. They are a red flag, a warning that something may be wrong and should be evaluated further. Generally, the greater the concentration of the abnormal substance (such as greatly increased amounts of glucose, protein, or red blood cells), the more likely it will be that there is a problem that needs to be addressed. But the results do not tell the doctor exactly what the cause of the finding is or whether it is a temporary or chronic condition. A normal urinalysis also 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 they may be missed by a single urine sample). In very dilute urine, small quantities of chemicals may be undetectable.
Is there anything else I should know?
The urinalysis is a set of screening tests that can provide a general overview of a person’s health. Your doctor must correlate the urinalysis results with your health complaints and clinical findings and search for the causes of abnormal findings with other targeted tests (such as a comprehensive metabolic panel (CMP), complete blood count (CBC), or urine culture (to look for a urinary tract infection).
Common Questions
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1. How long does it take to get results for urinalysis?
This depends on the laboratory and the equipment used. Usually, once the specimen is in the laboratory, the test takes approximately 30 minutes or less to complete.
2. Is the time of day a factor when collecting a urine sample?
Because this is a general screening test, time is usually not important, although a first morning void is usually preferred. However, if your doctor is looking for a specific finding, he may ask that you collect a sample at a specific time. For example, if he is looking for the excretion of glucose, it’s better to collect a specimen after a meal. If he is looking for low levels of protein, it’s better to collect a concentrated specimen, such as a first morning specimen.
3. Are there home test kits available?
Kits to perform a urinalysis are not available because the test requires special equipment and technical skills. However, some commercial testing strips can be purchased at a pharmacy to perform part of the chemical examination, such as urine pH, urine glucose, and urine ketones.
