Customarily called urinalysis, urine analysis is an inexpensive way to recognize and monitor disease. This is so effective large populations are screened using this technique. For example, a 2007 paper published by researchers from the Osaka School of Medicine reports that since the 1970s urinalysis has been routinely performed on workers, preschool and school-age children in Japan in much same way that vision and audio testing is done in United States schools.
Dipsticks
The most common form of urinalysis involves a dipstick test. Clinical workers dip a test strip similar to pH paper into a specimen of urine provided by the patient. Different regions of a single test strip are embedded with different reagents that change color in response to chemicals in the urine specimen. The resulting lab value is associated with the particular hue of the paper after dipping.
Tests
A single test strip measures pH, specific gravity, protein, glucose, ketones, nitrites, white blood cells, red blood cells and leuko-esterase. Out-of-range values for these measures raise the possibility of disease. For example, high urine protein is a red flag for kidney disease. High urine glucose is a red flag for diabetes. Nitrites are consistent with a urinary tract infection.
Limitations
Test strips do not provide precise information. For example, instead of measuring exactly how many milligrams of protein are in the urine, they provide approximations which are expressed as "negative," "trace," "+1". "+2," and so forth. The lack of precise measurement is not a drawback if the dipsticks are used as a screening tool. However, more precise testing using different techniques may be needed if any of the results are out-of-range.
A second limitation involves the accuracy test for red blood cells. Red blood cells tend to clump together on the test strip and cause the reading to be much higher than it really is. This can cause needless worry for patients whose results for blood in the urine are abnormally high. Both US Pharmacist and Medaille University urge that urine specimens be checked under a high-powered microscopic field if the dipstick test is out-of-range.
Home Tests
Since urinalysis is so easy and inexpensive, more and more patients are doing it at home. This is particularly for parents of kids with kidney disease. Common brand names for over-the-counter test strips include Albustix, which measures urine protein, and Clinistix, which measures urine glucose.
Other techniques
The University of Utah School of Medicine notes that there are other forms of urinalysis other than the dipstick. A visual examination of the color and clarity of the urine specimen can reveal issues in the body's ability to concentrate urine. Microscope examination is also helpful for counting red blood cells, white blood cells and bits of crud called casts.
