A urinalysis is a common test that's done for several reasons:

• To check your overall health. A urinalysis might be part of a routine medical exam, pregnancy checkup or pre-surgery preparation. Or it might be used to screen for a variety of disorders, such as diabetes, kidney disease or liver disease, when you're admitted to a hospital.
• To diagnose a medical condition. A urinalysis might be requested if you have abdominal pain, back pain, frequent or painful urination, blood in your urine, or other urinary problems. A urinalysis can help diagnose the cause of these signs and symptoms.
• To monitor a medical condition. If you've been diagnosed with a medical condition, such as kidney disease or a urinary tract infection, your doctor might recommend testing your urine regularly to monitor your condition and treatment.

Other tests, such as pregnancy testing and drug screenings, might rely on a urine sample, but these tests look for substances that aren't included in a typical urinalysis.

If you're having only a urinalysis, you can eat and drink before the test. If you're having other tests, you might need to fast before the test. Your health care provider will give you specific instructions.

Many drugs, including nonprescription medications and supplements, can affect the results of a urinalysis. Before a urinalysis, tell your doctor about medications, vitamins or other supplements you take.

You might collect a urine sample at home or at your health care provider's office. Providers typically give out containers for urine samples. You might be asked to collect the sample at home first thing in the morning, when your urine is more concentrated.

You might be instructed to collect the sample midstream, using a clean-catch method. This method involves the following steps:

• Cleanse the urinary opening. Women should spread the labia and clean from front to back. Men should wipe the tip of the penis.
• Begin to urinate into the toilet.
• Pass the collection container into your urine stream.
• Urinate at least 1 to 2 ounces (30 to 60 milliliters) into the collection container.
• Finish urinating into the toilet.
• Deliver the sample as directed by your health care provider.
• If you can't deliver the sample to the designated area within 60 minutes of collection, refrigerate the sample, unless your provider has told you otherwise.

In some cases, if needed, your provider can insert a thin, flexible tube (catheter) through the urinary tract opening and into the bladder to collect the urine sample.

The urine sample is sent to a lab for analysis. You can return to your usual activities immediately.

For a urinalysis, your urine sample is evaluated in three ways: visual exam, dipstick test and microscopic exam.

Visual exam

A lab technician examines the urine's appearance. Urine is typically clear. Cloudiness or an unusual odor can indicate a problem, such as an infection. Protein in urine can make it appear foamy.

Blood in the urine can make it look red or brown. Urine color can be influenced by what you've just eaten or by certain drugs you're taking. For example, beets or rhubarb might tint your urine red.

Dipstick test

A dipstick — a thin, plastic stick with strips of chemicals on it — is placed in the urine. The chemical strips change color if certain substances are present or if their levels are above typical levels. A dipstick test checks for:

• Acidity (pH). The pH level indicates the amount of acid in urine. The pH level might indicate a kidney or urinary tract disorder.
• Concentration. A measure of concentration shows how concentrated the particles are in your urine. A higher than normal concentration often is a result of not drinking enough fluids.
• Protein. Low levels of protein in urine are typical. Small increases in protein in urine usually aren't a cause for concern, but larger amounts might indicate a kidney problem.
• Sugar. The amount of sugar (glucose) in urine is typically too low to be detected. Any detection of sugar on this test usually calls for follow-up testing for diabetes.
• Ketones. As with sugar, any amount of ketones detected in your urine could be a sign of diabetes and requires follow-up testing.
• Bilirubin. Bilirubin is a product of red blood cell breakdown. Usually, bilirubin is carried in the blood and passes into your liver, where it's removed and becomes part of bile. Bilirubin in your urine might indicate liver damage or disease.
• Evidence of infection. Either nitrites or leukocyte esterase — a product of white blood cells — in your urine might indicate a urinary tract infection.
• Blood. Blood in your urine requires additional testing. It may be a sign of kidney damage, infection, kidney or bladder stones, kidney or bladder cancer, or blood disorders.

Microscopic exam

Sometimes performed as part of a urinalysis, this test involves viewing drops of concentrated urine — urine that's been spun in a machine — under a microscope. If any of the following levels are above average, you might need more tests:

• White blood cells (leukocytes) might be a sign of an infection.
• Red blood cells (erythrocytes) might be a sign of kidney disease, a blood disorder or another underlying medical condition, such as bladder cancer.
• Bacteria, yeast or parasites can indicate an infection.
• Casts — tube-shaped proteins — can be a result of kidney disorders.
• Crystals that form from chemicals in urine might be a sign of kidney stones.

A urinalysis alone usually doesn't provide a definite diagnosis. Depending on the reason your provider recommended this test, you might need follow-up for unusual results. Evaluation of the urinalysis results with other tests can help your provider determine next steps.

Getting standard test results from a urinalysis doesn't guarantee that you're not ill. It might be too early to detect disease or your urine could be too diluted. Tell your provider if you still have signs and symptoms.

For specifics about what your urinalysis results mean, talk with your health care provider.