Creatinine is a byproduct of muscle metabolism. Working muscles utilize chemicals, including creatine, to produce energy. Roughly 2 percent of total body creatine -- 95 percent of which is within the muscles -- is converted into creatinine daily. Creatinine enters the bloodstream and is subsequently filtered by the kidneys and excreted in the urine. Healthcare professionals most commonly measure the creatinine level to assess kidney function. However, other factors can affect creatinine level, including diet, muscle mass, some medications and chronic disease, such as hyperthyroidism, hypothyroidism and diabetes. Typical blood creatinine levels in healthy adults are approximately 0.7 to 1.2 mg/dL in men and 0.5 to 1.0 mg/dL in women, although reference ranges may vary slightly from one testing laboratory to another.
Symptoms Associated With Diseases That Cause Elevated Creatinine
An elevated creatinine does not directly cause any symptoms, in and of itself. However, people with a high creatinine might experience symptoms related to the underlying illness responsible for the elevation. Symptoms associated with a high creatinine are most often due to reduced kidney function. Examples include:
-- loss of appetite
-- nausea or vomiting
-- weight loss
-- itchy skin
-- swelling of the hands and feet
-- increased or decreased urination
-- colorless or dark urine
There might also be symptoms of a primary illness that has led to kidney disease, such as diabetes. Classic symptoms of diabetes include increased urination, thirst and hunger. Weight loss, lack of energy, poor concentration, blurred vision and tingling in the feet or hands are other possible symptoms of diabetes.
Considerations and Next Steps
A high creatinine level does not necessarily signal kidney disease or another illness. For example, your creatinine level might be higher than expected if you have more muscle mass than the average man or woman. Talk with your doctor about next steps of you have a high creatinine level. She might recommend rechecking the value or additional testing to determine the underlying cause.
Reviewed and revised by: Tina M. St. John, M.D.