High creatinine levels can mean a person is suffering from kidney damage, chronic kidney disease, heart disease or dehydration, according to WebMD. High levels can also mean the patient may be suffering from excessive blood loss, burns or some type of muscle condition.
The normal creatinine clearance levels for men under the age of 40 is between 107 and 139 milliliters per minute. For women under 40, the normal creatinine levels fall between 87 and 107 milliliters per minute. This value is determined by the amount of creatinine found in a person's blood and urine, explains WebMD. Creatinine clearance levels lower as a person ages and are also based on a person's size. Generally, levels go down 6.5 milliliters per minute for every 10 years after a person turns 20. The purpose of creatinine tests is to determine the function of a person's kidneys.
Kidney damage may be caused by trauma, cancer or shock, notes WebMD. Two types of creatinine tests are a blood test and the collection of urine over a 24-hour period. If a person has lower than normal creatinine levels, he could be suffering from liver disease or a muscular deficiency disorder. A person with a diet low in protein may also have lower creatinine levels.