Creatinine levels are often included in routine lab tests, since they provide insight into how well the kidneys are functioning. Creatinine--along with GFR and urine protein--are usually the first lab values that kidney patients look at when they get the results from routine blood work back. Knowing more about how creatinine is formed in the body helps patients take a more proactive role in their health.
Background
Just as the body produces waste products through the digestive process, it also produces waste products through muscular activity. When muscles are active, creatine phosphate breaks down to form creatinine, a waste product. Another common waste product is blood urea nitrogen (BUN). Since levels of physical activity remain relatively constant, serum creatinine levels remain constant in healthy people.
Kidney Impairment
Creatinine becomes a red flag for kidney disease because it is normally filtered from the blood by the kidneys. As kidney function declines, kidneys are less able to remove creatinine from the blood. Creatinine levels do not start to rise until renal function is significantly impaired, so it is not a good measure for early impairment. FPnotebook.com estimates that creatinine does not begin to increase until 25 to 50 percent of renal function is lost. A better value, called creatinine clearance, looks specifically at the rate at which creatinine is cleared from the blood.
Units
Interpreting lab values for creatinine can be a little confusing for patients because the values are expressed in different units in the United States and the U.K.: in the United States, creatinine is expressed in mg/dL; in the U.K., it is expressed in micromoles/dL. The American units can be converted to micromoles/dL by multiplying them by 88.4. Understanding conversion units is important when conducting library research because the literature for many kidney diseases uses both units.
Normal Values
Since creatinine is a byproduct of muscular activity, it follows that men normally have higher creatinine levels than women because men are usually more muscular than women. Likewise, adults have higher values than children. According to FPNotebook.com, normal values for women are between 0.6 to 1.0 mg/dL; for men between 0.8 to 1.3 mg/dL; and children's values are lower and depend on age.
Prevention/Solution
Restoring creatinine to normal levels might be possible for short-term acute diseases, but it is often difficult (if not impossible) for chronic diseases. That being said, treatment of kidney diseases is very important because renal patients often present with many symptoms that are treatable.
