Creatinine is a substance in the blood that is produced by the muscles and eliminated by the kidneys. Thus, by analyzing creatinine levels it is possible to identify if there is a problem in the kidneys, especially when it's level are increased in the blood, because it can mean that the kidneys are not being able to eliminate the creatinine and, therefore, it is being accumulated in the blood.
Normal blood creatinine values may vary from laboratory to laboratory but usually are:
- In women, 0.5 to 1.1 mg / dL
- In men, between 0.6 and 1.2 mg / dL
As creatinine is a substance that is produced in the body according to the level of muscle mass, it is normal for men to have higher levels of creatinine in the blood because they generally have more developed muscles than women.
What can cause high creatinine levels
When blood creatinine values are above normal they can indicate injury to the blood vessels of the kidneys, a kidney infection, or a reduction in blood flow to the kidneys, for example. Some symptoms that may also occur in cases of high creatinine levels include:
- Excessive tiredness;
- Swelling of the legs or arms;
- Feeling of shortness of breath;
- Frequent confusion;
- Nausea and vomiting.
However, athletes and bodybuilders may also have high creatinine levels due to high muscle activity and not because of an injury to the kidney.
When kidney problems are suspected, the doctor may also order the creatinine clearance test, which compares the amount of creatinine in the blood and urine. That way, if the problem is in the kidneys, the amount of creatinine in the blood should be higher than the amount in the urine, since the kidneys are not eliminating the substance.
What can cause low creatinine levels
Low blood creatinine levels are not a cause for concern and are more common in pregnant women and patients with liver disease, as the liver is also responsible for the production of creatinine.
However, in some people it may also indicate diseases in the muscles, such as muscular dystrophy, for example, which causes other symptoms such as weakness, muscle pain or difficulty moving the arms or legs.
How to take the creatinine test
The creatinine test is usually done through a blood test to assess the amount of the substance in the body, however, the doctor may also ask for a urinalysis. Depending on the type of examination, there are different procedures:
Blood creatinine test
In most cases, the only caution you need to have is to tell your doctor about medication you are using, as you may need to stop taking them before the test, especially cimetidine, aspirin, ibuprofen, or cephalosporins.
Urine creatinine test
This test is done during 24 hours, in which time all the urine that has been eliminated must be stored in the vial given by the laboratory.
To take the test, your doctor may recommend stopping some foods or even avoiding certain medications, depending on each case.