Urinalysis

This is a routine test used to screen for metabolic and kidney disorders and for urinary tract infections. It is often done as part of 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.

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.

PREPARATION FOR TEST

One to two ounces of urine are necessary with the first morning sample being the most valuable.

NORMAL FINDINGS

  • Appearance: clear

  • Color: amber yellow

  • Odor: aromatic

  • pH: 4.6-8.0 (average, 6.0)

  • Protein

  • 0-8 mg/dL

  • 50-80 mg/24 hr (at rest)

  • Less than 250 mg/24 hr (during exercise)

  • Specific gravity

  • Adult: 1.005-1.030 (usually, 1.010-1.025)

  • Elderly: values decrease with age

  • Newborn: 1.001-1.020

  • Leukocyte esterase: negative

  • Nitrites: none

  • Ketones: none

  • Bilirubin: none

  • Urobilinogen: 0.01-1 Ehrlich unit/mL

  • Crystals: none

  • Casts: none

  • Glucose

  • Fresh specimen: none

  • 24-hour specimen: 50-300 mg/24 hr or 0.3-1.7 mmol/day (SI units)

  • White blood cells (WBC's): 0-4 per low-power field

  • WBC casts: none

  • Red blood cells (RBC's): Less than or equal to 2

  • RBC casts: none

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.

MEANING OF TEST

Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.

OBTAINING THE TEST RESULTS

It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.