How the creatinine test is done and reference values

Creatinine is a substance in the blood that is produced by the muscles and eliminated in the kidneys. Thus, by analyzing creatinine levels, it is possible to identify if there is a problem with the kidneys, especially when it is increased in the blood, as it may mean that the kidneys are not able to eliminate creatinine and, therefore, it is being accumulated in the blood.

Normal blood creatinine values may vary by laboratory, but are usually:

In women, between 0.5 to 1.1 mg / dL; in men, between 0.6 to 1.2 mg / dL.

Since 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, as they generally have more developed muscles than women.

What can cause high creatinine

When blood creatinine levels are above normal, they may indicate an injury to the kidney's blood vessels, a kidney infection or reduced blood flow to the kidneys, for example. Some symptoms that can also arise in cases of high creatinine 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 due to high excessive muscle activity and not necessarily due to kidney problems.

When kidney problems are suspected, your doctor may also order a creatinine clearance test, which compares the amount of creatinine obtained in your blood and urine. Thus, if the problem is in the kidneys, the amount of creatinine in the blood must be higher than the amount in the urine, since the kidneys are not eliminating the substance. Learn more about the creatinine clearance exam.

What can cause low creatinine

Low blood creatinine values are not a cause for concern and are more frequent in pregnant women and patients with liver disease, since the liver is also responsible for the production of creatinine.

However, in some people it can also indicate diseases in the muscles, such as muscular dystrophy, for example, which causes other symptoms such as weakness, muscle pain or difficulty in 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 order a urine test. Depending on the type of exam, there are different precautions:

Blood creatinine test

In most cases, the only necessary precautions are to inform the doctor about the medications you are using, as it may be necessary to stop taking some medications before the test, especially cimetidine, aspirin, ibuprofen or cephalosporins.