Urinalysis

Definition

Urinalysis is the physical, chemical, and microscopic examination of urine. It involves a number of tests to detect and measure various compounds that pass through the urine.

Alternative Names

Urine appearance and color; Routine urine test

How the test is performed

A urine sample is needed. Your health care provider will tell you what type of urine sample is needed. For information on how to collect a urine sample, see:

• 24-hour urine collection
• Clean catch urine specimen

There are three basic steps to a complete urinalysis:

Physical color and appearance:

• What does the urine look like to the naked eye?
• Is it clear or cloudy?
• Is it pale or dark yellow or another color?

The urine specific gravity test reveals how concentrated or dilute the urine is.

Microscopic appearance:

• The urine sample is examined under a microscope. This is done to look at cells, urine crystals, mucus, and other substances, and to identify any bacteria or other microorganisms that might be present.

Chemical appearance:

• A special stick ("dipstick") tests for various substances in the urine. The stick contains little pads of chemicals that change color when they come in contact with the substances of interest.

See also: Urine chemistry

How to prepare for the test

Certain medicines change the color of urine, but this is not a sign of disease. Your doctor may tell you to stop taking any medicines that can affect test results.

Medicines that can change your urine color include:

• Chloroquine
• Iron supplements
• Levodopa
• Nitrofurantoin
• Phenazopyridine
• Phenothiazines
• Phenytoin
• Riboflavin
• Triamterene

How the test will feel

The test involves only normal urination, and there is no discomfort.

Why the test is performed

A urinalysis may be done:

• As part of a routine medical exam to screen for early signs of disease
• If you have signs of diabetes or kidney disease, or to monitor you if you are being treated for these conditions
• To check for blood in the urine
• To diagnose a urinary tract infection

Additional conditions under which the test may be performed:

• Acute bilateral obstructive uropathy
• Acute nephritic syndrome
• Acute tubular necrosis
• Acute unilateral obstructive uropathy
• Alkalosis
• Alport syndrome
• Analgesic nephropathy
• Anorexia nervosa
• Atheroembolic renal disease
• Atrial myxoma
• Bladder stones
• Chronic bilateral obstructive uropathy
• Chronic glomerulonephritis
• Chronic or recurrent urinary tract infection
• Chronic renal failure
• Chronic unilateral obstructive uropathy
• Chronic urethritis
• Complicated UTI (pyelonephritis)
• Congenital nephrotic syndrome
• Cystinuria
• Delirium
• Dementia
• Dementia due to metabolic causes
• Diabetes insipidus -- central
• Diabetic nephropathy/sclerosis
• Enuresis
• Epididymitis
• Failure to thrive
• Focal segmental glomerulosclerosis
• Goodpasture syndrome
• Heart failure
• Hemolytic-uremic syndrome (HUS)
• Henoch-Schonlein purpura
• Insulin-dependent diabetes (IDD)
• IgA nephropathy (Berger's disease)
• Injury of the kidney and ureter
• Interstitial nephritis
• Irritable bladder
• Left-sided heart failure
• Lupus nephritis
• Malignant hypertension (arteriolar nephrosclerosis)
• Medullary cystic kidney disease
• Membranoproliferative GN I
• Membranoproliferative GN II
• Membranous nephropathy
• Myelomeningocele (children)
• Necrotizing vasculitis
• Nephrotic syndrome
• Noninsulin-dependent diabetes (NIDD)
• Orchitis
• Ovarian cancer
• Paroxysmal nocturnal hemoglobinuria (PNH)
• Polycystic kidney disease
• Post-streptococcal GN
• Prerenal azotemia
• Primary amyloidosis
• Prostate cancer
• Prostatitis, acute
• Prostatitis, chronic
• Prostatitis, nonbacterial
• Pyelonephritis, acute
• Rapidly progressive (crescentic) glomerulonephritis
• Reflux nephropathy
• Renal papillary necrosis
• Renal tubular acidosis, distal
• Renal tubular acidosis, proximal
• Renal vein thrombosis
• Retrograde ejaculation
• Rhabdomyolysis
• Right-sided heart failure
• Secondary systemic amyloidosis
• Stress incontinence
• Systemic lupus erythematosus
• Systemic sclerosis (scleroderma)
• Thrombotic thrombocytopenic purpura
• Traumatic injury of the bladder and urethra
• Ureterocele
• Urethral stricture
• Urethritis
• Wegener's granulomatosis
• Wilms tumor

Normal Values

Normal urine may vary in color from almost colorless to dark yellow. Some foods (like beets and blackberries) may turn the urine a red color.

Usually, glucose, ketones, protein, and bilirubin are not detectable in urine. The following are not normally found in urine:

• Hemoglobin
• Nitrites
• Red blood cells
• White blood cells

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

For specific results, see the individual test article:

• Bilirubin - urine
• Glucose - urine
• Protein - urine
• Red blood cells in urine test
• Urine ketones
• Urine pH
• Urine protein
• Urine specific gravity

What the risks are

There are no risks.

Special considerations

If a home test is used, the person reading the results must be able to distinguish between different colors, since the results are interpreted using a color chart.

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References

McPherson RA, Ben-Ezra J, Zhao S. Basic examination of urine. In: McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: W.B. Saunders Company; 2006:chap 27.