Normal BUN levels range from 6 to 20 milligrams per deciliter, according to MedlinePlus. In women, normal creatinine levels are between 0.6 and 1.1 milligrams per deciliter, while men's run from 0.7 to 1.3.
A BUN, or blood urea nitrogen, test determines how much urea nitrogen is in the blood, MedlinePlus explains. While this test is often used to examine kidney function, high levels may be indicative of problems such as congestive heart failure, heart attack or gastrointestinal bleeding.
The creatinine blood test is also used to check kidney function, states MedlinePlus. Abnormal results may be caused by kidney infection or failure, a blocked urinary tract, preeclampsia or muscular dystrophy.