Final answer:
Option A. The test called Blood urea nitrogen (BUN) is used to evaluate kidney or liver function. It measures the amount of urea nitrogen in the blood, with normal levels falling between 8-20 mg/dL. Elevated BUN levels may indicate kidney dysfunction or liver disorders.
Step-by-step explanation:
The test used in the evaluation of kidney or liver disease is called Blood urea nitrogen (BUN). This blood test measures the amount of urea nitrogen present in the blood, which is an important indicator of kidney function. The kidneys filter out urea, which is a waste product formed during the breakdown of proteins. Normal BUN levels are typically between 8-20 mg/dL. However, elevated levels can indicate kidney dysfunction or disease, whereby the kidneys are unable to properly remove urea from the blood, leading to a condition known as uremia.
Urea is synthesized in the liver from ammonia, and under normal conditions, the concentration of urea in the blood is maintained at 15-40 mg/100 ml. Blood tests that include BUN are part of liver function tests (LFTs) as well, as alterations in urea levels can also reflect liver disorders. Methods for estimating blood urea include the Diacetyl Monooxime (DAM) method, colorimetric method using urease enzyme, and autoanalyser methods.
Besides the BUN, other tests are used to assess kidney function such as creatinine levels, urine flow, and urinalysis. These tests can help diagnose other conditions like diabetes mellitus, which is checked through different tests, such as Benedict's test for glucose in urine.