Creatinine is included in most routine lab work because it is the most reliable indicator of kidney health. Kidney patients should know what creatinine is, how it is measured and what their creatinine values mean. Many patients find it helpful to maintain a spreadsheet of their creatinine levels. This data provides insight into how fast kidney disease is progressing.
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Creatinine is a waste product produced by the muscles. It should not be confused with creatine. Creatine is found in muscles. When muscles work hard, they convert creatine into creatinine.
Both blood urea nitrogen, or BUN, and creatinine are nitrogenous wastes produced by the muscles. Unlike BUN, creatinine levels remain relatively stable in healthy people.
Creatinine is measured in milligrams per deciliter (mg/dl) in the U.S. and in micromoles per liter (?/l) in Europe and Canada. Check what units are being used if a creatinine value seems impossibly high or low.
Multiply by 88.4 to convert between milligrams per deciliter to micromoles per liter. For example, a creatinine value of 0.6 mg/dl is equivalent to 53.04 ?/l.
Patients who change medical providers should not be surprised if their lab results edge up or down because there are slight variations in how labs measure creatinine. Such changes are normal.
Men usually have higher creatinine values than women because they are more muscular. Similarly, adults have higher normal values than children.
According to the Family Practice Notebook, normal creatinine values for adult males are between 0.8 and 1.3 mg/dl. Normal values for women are between 0.6 and1.0 mg/dl. Normal values for children are lower. They depend upon the age and size of the child.
While there is no such thing as abnormally low creatinine levels, abnormally high levels can be symptomatic of many kidney disorders ranging from diabetes, glomerular disease, birth defects such as renal dysplasia and many other kidney diseases. If creatinine levels are abnormally high on repeated tests, additional diagnostic work will be necessary to determine the nature of the disorder. These tests might include urinalysis, ultrasound and kidney biopsy.
Serum creatinine levels are different from urine creatinine levels. Urine creatinine levels are used to calculate other values such as protein creatinine ratios or calcium creatinine ratios. Urine creatinine levels should not be confused with serum creatinine levels because taken alone, urine levels are not indicators of disease.
If serum creatinine levels are not normal, it is important to get the test repeated before panicking. Many factors such as dehydration can throw off an otherwise normal value.