A normal serum creatinine level ranges from 0.6 to 1.1 milligrams per deciliter in women and 0.7 to 1.3 milligrams per deciliter in men, states MedlinePlus. Men usually have a greater muscle mass than women, which results in their having a higher serum creatinine level than that of women. The creatinine test is used to determine how well the kidneys function.
Creatinine is a waste product created by the breakdown of creatine, notes MedlinePlus. Creatine is used by the muscles as a source of fuel. The kidneys are responsible for removing creatinine from the bloodstream, so checking a serum creatinine level determines if the kidneys are filtering waste products normally. Some causes of an elevated creatinine level are kidney infections, kidney disease, urinary blockages, muscle problems and pregnancy complications. Abnormally low levels, on the other hand, may indicate conditions such as muscular dystrophy and myasthenia gravis.