For most types of cancer, a biopsy is the main way doctors diagnose cancer. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. Your doctor may recommend a biopsy if something suspicious is found during a physical exam or another test.
Blood urea nitrogen - BUN - is a blood test performed as a marker of kidney function. It is part of the basic metabolic panel done for health screening. It is also used to monitor the progression of kidney failure. BUN is produced by the breakdown of protein and usually cleared from the blood by the kidneys.
BUN (blood urea nitrogen) is a blood test to check kidney function. So is the serum creatinine test. When your doctor talks about BUN/creatinine levels or a BUN-to-creatinine ratio, he or she is referring to the two main blood tests that tell how well the kidneys are filtering waste products from your blood. The ratio of BUN to creatinine is normally in the range of 10:1 to 20:1.