Urinalysis is an analysis of the urine. This test is often performed for a variety of reasons, including to check on kidney function, evaluate for the presence of diabetes, or to help diagnose a urinary tract infection.1,2 Urinalysis may be performed during the diagnosis or treatment planning stage to help evaluate kidney function. It may also be used during treatment or after treatment is completed to help assess kidney function and general health.3
Some other tests, like those for pregnancy or to screen for drug use, also use urine samples, but these tests are not generally included in a traditional urinalysis.2
During a urinalysis, the laboratory will evaluate the urine for its color, appearance, odor, pH (acidity) level, and the presence of any proteins, glucose (sugar), ketones, bilirubin, crystals, bacteria, or other microorganisms.1
Preparing for a urinalysis
There is no special preparation for a urinalysis, and patients are advised to eat and drink normally. Some people may find it helpful to drink extra fluids before their doctor's appointment so that they will be able to urinate, but other tests may be performed on a sample of urine that is collected first thing in the morning. The sample may be collected at home or at a doctor's office or hospital, depending on the individual situation.2
For the best results, patients are instructed to clean the urinary opening and urinate a small amount into the toilet before collecting the urine sample. The collection container (like a cup) can then be passed into the urine stream. Any excess urine can be eliminated into the toilet. Another method of collecting the urine sample is to use a catheter, a thin, flexible tube that is threaded through the urinary tract opening up to the bladder.2
The results of urinalysis
The sample is sent to the laboratory for analysis, which will include a visual inspection, dipstick tests, and microscopic examination. The visual inspection will note the color and clarity of the urine sample. Cloudiness may indicate infection, while the color may be reddish or brown if the urine contains blood. However, the color of urine can also be affected by certain foods, like beets or rhubarb.2
Dipsticks are thin strips with chemicals on them that react to the presence of certain compounds, like proteins or acid. Dipsticks are used to test the concentration of urine, which may indicate dehydration or not drinking enough liquids, as well as the acidity (pH) and the presence of proteins, sugar (glucose), ketones, bilirubin, blood, or compounds that are produced by white blood cells (nitrites or leukocyte esterase), which may indicate infection.2
A small sample of urine is placed on a slide for examination under a microscope. The laboratory will look for the presence of white blood cells, red blood cells, bacteria, yeast, casts (tube-shaped proteins), or crystals. A higher than normal level of these cells or substances may indicate an infection or other health condition. However, a urinalysis alone may not be able to provide all the information needed to make a diagnosis, and your doctor may order additional tests based on the urinalysis results.2