Blood Urea Nitrogen (BUN)
Blood test that measures blood’s content of urea. When you eat protein, your blood carries some of it to your cells; and what’s left over is a waste called urea (which contains nitrogen). Healthy kidneys get rid of urea in the urine and when the kidneys fail, urea stays in the blood. So, the BUN test is used primarily to evaluate renal (kidney) function by measuring the urea found in the blood stream. It may also indicate liver disease or dehydration. In HUS, BUN level rises well above normal, indicating that kidneys are not filtering the blood properly.