what is a creatinine
Creatinine is a natural product of muscle breakdown that occurs at a low level in the body. Both BUN and creatinine are filtered by the kidney and excreted in urine. For this reason, BUN and creatinine are used together to measure kidney function. If kidney function begins to decline, BUN and creatinine rise. A normal creatinine depends on muscle mass and age. In general, a normal creatine is 0.5 to 1.2 milligrams per deciliter (mg/dL). A normal BUN is 7 to 20 mg/dL. Remember that different laboratories use different testing equipment, and may have slightly different ranges for normal.