The normal range for creatinine levels is 0.6 to 1.3 milligrams per deciliter, according to MedlinePlus. However, this range may vary from one lab to another because different labs may test different samples. Another reason for the variation may be varying lab measurements.
In the body, the creatinine level increases with muscle mass, explains MedlinePlus. As a result, the levels of creatinine in men are typically higher than in women. Since it is the function of the kidneys to eliminate creatinine from the body, an increase in the level of creatinine implies a kidney malfunction.
Typically, doctors test the level of creatinine in the blood in order to determine the efficiency of the kidneys, says MedlinePlus. Because some medications such as cimetidine, trimethoprim, cisplatin and cephalexin may influence the test results, the doctor may request the patient to stop taking them before the test. During the test, the doctor inserts a needle into a blood vessel of the patient and draws a blood sample.
The creatinine test results may be normal, lower or higher than normal, as MedlinePlus reports. While the lower-than-normal results may imply the presence of muscular dystrophy and myasthenia gravis, a person with higher-than-normal results may have a blocked urinary tract, kidney failure, low kidney blood flow or dehydration.