For urinalysis, your urine sample is evaluated in three ways: visual exam, dipstick test and microscopic exam.
A lab technician will examine the urine's appearance. Urine is typically clear. Cloudiness or unusual odor may indicate a problem. Blood in the urine may make it look red or brown. A cloudy appearance may indicate an infection. Urine color can be influenced by what you've just eaten. For example, beets may add a red tint to your urine.
A dipstick — a thin, plastic stick with strips of chemicals on it — is placed in the urine to detect abnormalities. The chemical strips change color if certain substances are present or if their levels are above normal. A dipstick test checks for the following:
- Acidity (pH). The pH level indicates the amount of acid in urine. Abnormal pH levels may indicate a kidney or urinary tract disorder.
- Concentration. A measure of concentration, or specific gravity, shows how concentrated particles are in your urine. Higher than normal concentration often is a result of not drinking enough fluids.
- Protein. Low levels of protein in urine are normal. Small increases in protein in urine usually aren't a cause for concern, but larger amounts may indicate a kidney problem.
- Sugar. Normally the amount of sugar (glucose) in urine is 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. Normally, bilirubin is carried in the blood and passes into your liver, where it's removed and becomes part of bile. Bilirubin in your urine may indicate liver damage or disease.
- Evidence of infection. If either nitrites or leukocyte esterase — a product of white blood cells — is detected in your urine, it may be a sign of 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.
Several drops of the urine are examined with a microscope. If any of the following are observed in above-average levels, additional testing may be necessary:
- White blood cells (leukocytes) may be a sign of an infection.
- Red blood cells (erythrocytes) may be a sign of kidney disease, a blood disorder or another underlying medical condition, such as bladder cancer.
- Epithelial cells — cells that line your hollow organs and form your skin — in your urine may be a sign of a tumor. But more often, they indicate that the urine sample was contaminated during the test, and a new sample is needed.
- Bacteria or yeasts may indicate an infection.
- Casts — tube-shaped proteins — may form as a result of kidney disorders.
- Crystals that form from chemicals in urine may be a sign of kidney stones.
Urinalysis alone usually doesn't provide a definite diagnosis. Depending on the reason your doctor recommended this test, abnormal results may or may not require follow-up. Your doctor may need to evaluate the results along with those of other tests, or additional tests may be necessary to determine next steps.
For example, if you are otherwise healthy and have no signs or symptoms of illness, results slightly above normal on a urinalysis may not be a cause for concern and follow-up may not be needed. However, if you've been diagnosed with kidney or urinary tract disease, elevated levels may indicate a need to change your treatment plan.
For specifics about what your urinalysis results mean, talk with your doctor.
Feb. 15, 2014
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