A creatinine test is used to discover information about the kidneys. Creatinine is a form of chemical waste that our bodies produce when we eat meat but mostly due to muscle metabolism. If the kidneys are healthy, they are able to filter creatinine as well as other wastes out of the blood, sending them out of your body via urine. When the kidneys aren’t healthy, however, creatinine can accumulate in the bloodstream. Because of this, creatinine tests measure the amount of creatinine in urine (for a creatinine urine test) or blood (in a serum creatinine test) and use this information to determine whether the kidneys are functioning normally.
The 24 hour sample of urine creatinine will usually range between 500 and 2000 mg/day. The specific results will vary based on a person’s lean body mass and age. For men, the normal range should be between 14 and 26 mg per kilogram of body mass each day and for women these values should be between 11 and 20. It is important to note that the results can vary slightly depending on the lab.
If a person has abnormal results on their urine creatinine levels, it can mean any number of problems, some of which are minor and others of which are more serious. Some of these include urinary tract obstruction, rhabdomyolysis, reduced blood flow in the kidneys, prerenal azotemia, myasthenia gravis, late stage muscular dystrophy, kidney failure, kidney infection, a diet high in meat and glomerulonephritis.
Women usually have lower results on the serum creatinine test because they have a lower muscle mass in their bodies. The average range for women is between 0.6 and 1.1 mg/dL and for men it increases to between 0.7 and 1.3 mg/dL. As with the urine creatinine test, the average results can vary depending on the lab and their specific tests and procedures.
If you have abnormal results on your serum creatinine test, it can indicate many possibilities, some serious and others minor. Levels that are too high can be due to urinary tract obstruction, rhabdomyolysis, and reduced blood flow to the kidneys, pyelonephritis, preeclampsia, muscular dystrophy, kidney failure, glomerulonephritis, eclampsia, diabetic nephropathy, dehydration or acute tubular necrosis. Low levels can be due to late stage muscular dystrophy or myasthenia gravis.
Because having the serum creatinine test done only involves drawing blood, the risk is very minimal. However, some people have smaller or larger veins and arteries which can make the procedure more difficult. Some possible risks associated with drawing blood for the test include infection, hematoma, fainting or light-headedness and excessive bleeding, although all are minimal.