Urine testing

Urinalysis
White blood cells seen under a microscope from a urine sample.
Specialty	clinical pathology
MeSH	D016482
Other codes	LOINC Codes for Urinalysis panels
MedlinePlus	003579
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Clinical urine tests are various tests of urine for diagnostic purposes. The most common is a urinalysis (UA), one of the most common methods of medical diagnosis. The word is a portmanteau of the words urine and analysis. Other tests are urine culture (a microbiological culture of urine) and urine electrolyte levels.

The target parameters that can be measured or quantified in urinalysis include naked-eye (gross) examination for color and smell plus analysis for many substances and cells, as well as other properties, such as specific gravity.

A part of a urinalysis can be performed by using urine test strips, in which the test results can be read as color changes. Another method is light microscopy of urine samples.

Urine test results should always be interpreted using the reference range provided by the laboratory that performed the test, or using information provided by the test strip/device manufacturer.

In addition to the substances mentioned in tables below, other tests include a description of color and appearance.

The following are examples of color change causes and not a complete listing.

The odor (scent) of urine can normally vary from odorless (when very light colored and dilute) to a much stronger odor when the person is dehydrated and the urine is concentrated. Brief changes in odor are usually merely interesting and not medically significant. (Example: the abnormal smell many people can detect after eating asparagus.) The urine of diabetics experiencing ketoacidosis (urine contains high levels of ketone bodies) also may also have an abnormal odor.

A sodium-related parameter is fractional sodium excretion, which is the percentage of the sodium filtered by the kidney which is excreted in the urine. It is a useful parameter in acute renal failure and oliguria, with a value below 1% indicating a prerenal disease and a value above 3% indicating acute tubular necrosis or other kidney damage.