Urine analysis (or urinalysis, as it is commonly known) refers to a wide range of different tests which are employed in both human and veterinary medicine for a variety of screening and diagnostic applications.
There are even forms of urinalysis testing systems which are available to the consumer over the counter (many home pregnancy tests, for example). Whether to establish a diagnosis on the basis of the presence of microbes or the telltale signs of microbial activity in the urine, to measure the content of specific compounds or metabolites in the urine such as in drug testing applications or any of the numerous other applications, urine analysis is often an important part of health maintenance and courses of therapeutic treatment.
The first step in most urinalysis procedures is to visually inspect the urine, checking for cloudiness in the urine which may indicate an abnormally large amount of proteins or other cellular material in the urine. The color of the urine is also examined, since color can indicate certain conditions; for example, a red or reddish brown cast in a urine sample is often a sign of hemoglobin or myglobin in the urine (though it can also be caused by some drugs, food coloring additives or even eating fresh beets).
Protein screening is another common urine analysis task, particularly in the case of patients providing a cloudy or otherwise turbid urine sample; a protein screen can determine if the patient may be suffering from nephritic syndrome or other kidney ailments. Urine is also commonly screened for glucose content, an excessive amount of which in the urine generally indicated diabetes.
Urinalysis can be used to diagnose some bacterial and viral infections, such as E. coli, which is detectable in urine tests when a positive result is obtained from a nitrite test. Gram-negative rod shaped bacteria (including E. coli) tend to produce these results in when a urine analysis procedure is performed. Urine may also be tested for the presence of bacteria by being cultured and bacterial colonies counted.
The specific gravity of the urine is also generally measured as part of urinalysis procedures – the specific gravity can reveal much about the state of the patient’s health, particularly as this relates to their kidneys. This measurement is made by comparing the urine’s specific gravity compared to that of plain water.
The pH of the urine is measured using a dipstick and the urine is also checked for the levels of ketones (compounds produced by the breakdown of fats by the digestive system). The concentration of ketones in the urine can indicate diabetes or a insufficient caloric intake, among other conditions. Urine analysis may also include testing for the presence of lysed white blood cells, something which is often symptomatic of a urinary tract infection.
Naturally, a diagnosis is not made on the basis of a urine test alone; a more general examination of the patient is also made before any diagnosis can be definitively established. Urinalysis is just one part of the diagnostic process, but one which is a very important step in assessing the health of patients and determining the most appropriate course of treatment.