Final answer:
A physician orders a urea test primarily to evaluate kidney function, as elevated blood urea levels may indicate a kidney disorder. The test measures blood urea nitrogen (BUN) and can help diagnose and monitor changes in kidney health.
Step-by-step explanation:
The purpose of a physician ordering a urea test is b) To evaluate kidney function. Urea is synthesized in the liver and plays a crucial role in the detoxification process, converting toxic ammonia into a non-toxic, water-soluble compound that can be excreted by the kidneys. The normal concentration of urea in the blood is maintained between 15-40 mg/100 ml. An increase in the blood urea level, a condition known as uremia, can indicate kidney disorder when levels rise above 300 mg/dl. Blood tests that assess renal function look at blood urea nitrogen (BUN) levels as well as plasma creatinine, among other parameters. Therefore, measuring urea is a key part of diagnosing and monitoring kidney health.
The methods available for estimating blood urea include the Diacetyl Monooxime (DAM) method, colorimetric methods using the urease enzyme, and autoanalyser methods. A urea clearance test may also be conducted to further evaluate kidney function.