Urinalysis (Urine Test)

1 What is an Urinalysis (Urine Test)?

A urinalysis is an analysis of the urine done in many healthcare settings including doctors' offices, urgent care facilities, laboratories, and hospitals.

It is ordered by the doctor for: routine medical evaluation, assessing particular symptoms, for diagnosing medical conditions or for monitoring disease progression and response to therapy.

A small urine sample (30-60 ml’s) is collected from the patient in a specimen cup for evaluation by its physical appearance (color, cloudiness, odor, and clarity), macroscopic analysis and analysis based on its chemical and molecular properties or microscopic assessment.

Before taking a sample of urine, a woman must clean the area around the urethra with a special cleansing wipe, by spreading the labia of the external genitals and cleaning from front to back (toward the anus) and a man must wipe the tip of the penis with a cleansing pad.

After the initial part of urine is disposed of in the toilet, the urine is collected in a specimen cup. This is called the clean catch or the midstream urine collection.

In some patients, urine can be collected by placing a catheter (a small rubber tube) through the outside opening to the bladder (urethra) to collect the sample directly from the bladder.

The urine sample must be taken to the laboratory for analysis, typically within one hour of collection and if transportation could take longer, then the sample may be refrigerated.

Urine dipstick chemical analysis is done with a narrow plastic strip which has several squares of different colors attached to it which represents a component of the test used to interpret urinalysis like acidity of the urine, glucose, specific gravity, protein in the urine, ketones, etc. During the test the entire strip is dipped in the urine sample and color changes in each square are noted.

The main advantage of dipsticks is that they are convenient, easy to interpret, cost-effective and the result is available in few minutes.

The main disadvantage is that the information may not be very accurate as the test is time-sensitive and it provides limited information about the urine because normal and abnormal values are not reported as part of urinalysis results.

Macroscopic urinalysis is the direct visual observation of the urine, noting its quantity, color, clarity or cloudiness, etc. to suggest possibility of dehydration, an infection, red blood in the urine (hematuria), liver disease or breakdown of muscle.

The microscopic urinalysis is the study of the urine sample under a microscope by detecting cells and cellular debris, bacteria, and crystals in the urine which can suggest infections, traumas and tumors of the bladder and kidney, kidney stones and rarely, a urinary tract cancer.

Other commonly performed urine tests are drug tests, pregnancy tests, specific chemicals and proteins in the body, but they are not a part of routine urinalysis.