Signs that point to chronic kidney disease
Creatinine is a chemical waste molecule that is generated from muscle metabolism. The kidneys filter out most of the creatinine and dispose of it in the urine. If your kidneys are damaged and cannot function properly, the amount of creatinine in your urine decreases, while the level in your blood increases.
2. Blood urea nitrogen (BUN)
The BUN level is used to help determine kidney function and usually is compared and/or obtained along with blood creatinine levels. If BUN levels are high, it is often an indication of impaired kidney function. A BUN-to-creatinine ratio can help your doctor check for problems, such as dehydration, which can be a cause of abnormal BUN and creatinine levels.
3. Glomerular filtration rate (GFR)
Measurement of creatinine is used by doctors to calculate the glomerular filtration rate (GFR) of the kidneys. This is important because as the blood creatinine rises, GFR falls and the kidneys' ability to clear wastes from the body diminishes. It is ideal to have a high GFR rate (greater than 90 mL/min/1.73 m2). A high GFR along with the absence of protein in the urine indicates normal kidney function.2