A blood urea nitrogen (BUN) test is performed primarily to diagnose issues with which organ?

The blood urea nitrogen (BUN) test is primarily performed to assess kidney function. Urea is a waste product formed in the liver after proteins are metabolized, and it is typically excreted by the kidneys in urine. Therefore, measuring the level of BUN in the blood can provide valuable information about how well the kidneys are functioning. Elevated BUN levels may indicate that the kidneys are not filtering waste effectively, which can be a sign of kidney disease or dysfunction.

In contrast, while the liver is involved in the production of urea, the primary function assessed by the BUN test specifically targets the kidneys. Other organs listed in the options do not have a direct relationship with the BUN measurement, making them less relevant to this specific test.