It is a routine examination of the urine for cells, tiny structures, bacteria, and chemicals that suggest various illnesses. A urine culture attempts to grow large numbers of bacteria from a urine sample to diagnose a bacterial urine infection.
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:
1. 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.
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.
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.
Click to See : Urine chemistry
How to Prepare for the Test:
For a regular urinalysis, you are asked to urinate briefly into a plastic cup. When urine is collected for a urine culture, you must provide a “clean catch” sample – one that is not contaminated by skin cells and skin bacteria. This is so the doctor can obtain a sample of urine from inside your bladder, where normally there should be no bacteria. In contrast, there are many bacteria on the skin of a penis or in a vagina. The trick (harder for a woman than a man) is to pee directly into a sterile container without having the stream of urine first touch your skin or the nonsterile tissues of the vagina.
To collect a clean catch sample, you are given a sterile plastic container and asked to wipe off the area around your urethra (where urine exits) with an antiseptic cloth. For women, it’s also helpful to hold the two labia (outer walls) of the vagina apart with one hand when you urinate, so that the stream of urine passes directly into the sterile container. Since the first flow of urine is most likely to be contaminated by bacteria from around the opening of the urethra, first urinate for a moment into the toilet and then use the cup to collect the “middle” portion of your urine stream.
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:
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
*Atheroembolic renal disease
*Chronic bilateral obstructive uropathy
*Chronic or recurrent urinary tract infection
*Chronic renal failure
*Chronic unilateral obstructive uropathy
*Complicated UTI (pyelonephritis)
*Congenital nephrotic syndrome
*Dementia due to metabolic causes
*Diabetes insipidus — central
*Failure to thrive
*Focal segmental glomerulosclerosis
*Hemolytic-uremic syndrome (HUS)
*Insulin-dependent diabetes (IDD)
*IgA nephropathy (Berger’s disease)
*Injury of the kidney and ureter
*Left-sided heart failure
*Malignant hypertension (arteriolar nephrosclerosis)
*Medullary cystic kidney disease
*Membranoproliferative GN I
*Membranoproliferative GN II
*Noninsulin-dependent diabetes (NIDD)
*Paroxysmal nocturnal hemoglobinuria (PNH)
*Polycystic kidney disease
*Rapidly progressive (crescentic) glomerulonephritis
*Renal papillary necrosis
*Renal tubular acidosis; distal
*Renal tubular acidosis; proximal
*Renal vein thrombosis
*Right-sided heart failure
*Secondary systemic amyloid
*Systemic lupus erythematosus
*Systemic sclerosis (scleroderma)
*Thrombotic thrombocytopenic purpura
*Traumatic injury of the bladder and urethra
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, bilirubin, are not detectable in urine. The following are not normally found in urine:
*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 specific gravity
How long is it before the result of the test is known?
Your doctor might be able to do a urinalysis in his or her office and can give you the results within 10-15 minutes. If the urine is sent to a separate laboratory, it usually takes several hours to get results, so you may not hear from your doctor until the next day. A urine culture takes 24 to 72 hours to complete, so you may not hear results for several days.
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