| Urine test | |
|---|---|
 A urine sample in a sterile container |
Aurine test is anymedical test performed on aurine specimen. The analysis of urine is a valuable diagnostic tool because its composition reflects the functioning of many body systems, particularly thekidneys andurinary system, and specimens are easy to obtain.[1] Common urine tests include the routineurinalysis, which examines the physical, chemical, and microscopic properties of the urine;urine drug screening; andurine pregnancy testing.
The value of urine for diagnostic purposes has been recognized since ancient times. Urine examination was practiced inSumer andBabylonia as early as 4000 BC, and is described in ancientGreek andSanskrit texts.[2] Contemporary urine testing uses a range of methods to investigate the physical and biochemical properties of the urine. For instance, the results of the routineurinalysis can provide information about the functioning of thekidneys andurinary system; suggest the presence of aurinary tract infection (UTI); andscreen for possiblediabetes orliver disease, among other conditions.[3] Aurine culture can be performed to identify the bacterial species involved in a UTI.[4] Simplepoint-of-care tests can detectpregnancy by identifying the presence ofbeta-hCG in the urine[5] and indicate the use ofrecreational drugs bydetecting excreted drugs or their metabolites.[6] Analysis of abnormal cells in urine (urine cytology) can help to diagnose somecancers,[7] and testing fororganic acids oramino acids in urine can be used to screen for somegenetic disorders.[8]
The techniques used to collect urine specimens vary based on the desired test. A random urine, meaning a specimen that is collected at any time, can be used for many tests. However, a sample collected during the first urination of the morning (first morning specimen) is preferred for tests like urinalysis and pregnancy screening because it is typically more concentrated, making the test moresensitive.[1][9] Because the concentration of many substances in the urine varies throughout the day, some tests require timed urine collections, in which the patient collects all of their urine into a container for a given period of time (commonly 24 hours). A small amount of the specimen is then removed for testing. Timed collections are commonly used to measurecreatinine,urea,urine protein,hormones andelectrolytes.[1][10]
If urine is needed formicrobiological culture, it is important that the sample is not contaminated. In this case, the proper collection procedure involves cleaning the genital area, beginning to urinate into the toilet, and then filling the specimen container before completing the urination into the toilet. This is called a "midstream clean catch" collection.[1] Research has shown many women are unsure of how to take a midstream sample or why it is needed.[11][12]
If the subject is not able to urinate voluntarily, samples can be obtained using aurinary catheter or by inserting a needle through the abdomen and into the bladder (suprapubic aspiration).[3] In infants and young children, urine can be collected into a bag attached to the genital region, but this is associated with a high risk of contamination.[1]
Some examples of urine tests include:
