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Reference Value of Creatinine Levels By Age

February 27, 2021

Diagnostic tests such as blood urea nitrogen and creatinine test are conducted to evaluate the health of the kidneys and liver. So, what are the normal creatinine levels by age as well as the average BUN values? Plus, what do abnormal values of these tests indicate?

Diagnostic Tests

A creatinine test evaluates the amount of creatinine in the blood against the normal levels. Creatinine is a waste product that is filtered by the kidneys which comes from constant use of the muscles. On the other hand, a BUN test measures nitrogen levels in the blood that is a product of urea which is a waste product of protein.


Why Are These Tests Done?

As mentioned, these diagnostic tests are usually included in an individual’s regular checkup. It is part of routine blood examinations done to evaluate one’s overall health. However, a doctor might also recommend these tests, especially if an individual manifests symptoms associated with kidney and liver diseases.

An individual with a history of high blood pressure, diabetes, and a family history of kidney disease is at a heightened risk of kidney disorders. Moreover, an individual is at a higher risk of kidney disease if he or she is of American Indian, Asian, Hispanic, Pacific Islander, or African American descent. Here are the signs linked to kidney damage or disease that one should be well aware of.

  • Blood in Urine
  • Frequent Urination
  • Frequent Tiredness
  • Itchy and Dry Skin
  • Muscle Cramps
  • Poor Appetite
  • Painful Urination
  • Puffiness Around the Eyes
  • Swelling of the Ankles or Feet


Individuals who are also currently undergoing treatment for kidney disease are advised to take a BUN and creatinine test. Such tests evaluate the efficiency and effectiveness of the treatment. Before a test, the healthcare provider in-charge will ask questions about your diet, current medications, and supplements, as well as physical activity.

It is essential to mention all medications, whether prescription or non-prescription, that one is currently taking. Also, mention any history of family diseases related to the kidneys or livers. Usually, the test does not require that an individual fast. Food and water may still be consumed before the test.

A creatinine and BUN test involves blood extraction from the hand or arm. Afterward, the blood is sent to a laboratory for analysis.


Results of Tests

For a creatinine test, the normal creatinine levels by age are as follows.

  • Adult Males: 0.9 to 1.3 mg per dL
  • Adult Females: 0.6 to 1.1 mg per dL
  • Children (Age 3 to 18 Years Old): 0.5 to 1.0 mg per dL
  • Children Under Three Years Old: 0.3 to 0.7 mg per dL


Take note that the average values depend on the muscle mass of an individual. Moreover, the values are higher in men than in women. Also, the results vary and are dependent on an individual’s health history, age, and method utilized for the test.

normal creatinine levels by age

As for a BUN test, the average results are as follows.

  • Adults: 10 to 20 mg per dL
  • Children: 5 to 16 mg per dL

The average values vary per lab. Also, these results are compared with other tests and are not deemed final. Abnormal levels do not immediately indicate that an individual has damage to the kidneys or liver.


Abnormal Levels


A. High Level of Creatinine

If there is a high amount of creatinine in the blood, then it could likely indicate any of the following conditions.

  • Kidney Obstruction: The presence of kidney stones or enlarged prostate may block the flow of urine. This could likely result in kidney obstruction where the blockage impairs kidney function. It leads to high levels of creatinine.
  • Chronic Kidney Disease: Kidneys that are already damaged are ineffective at filtering creatinine from the blood. This results in high values of the byproduct.
  • Overconsumption of Protein: Consuming excessive amounts of protein has an impact on an individual’s creatinine values. Consuming more than the recommended dietary allowance of meat that contains creatinine is likely to lead to abnormally high levels of the byproduct.
  • Dehydration: When an individual fails to consume the recommended amount of water in a day, it may lead to dehydration. Severe levels of dehydration result in a heightened risk for kidney damage that affects the level of creatinine in the blood.
  • Medications: Some medicines like H2 blockers, trimethoprim, and antibiotics are likely to boost the level of creatinine in the blood. However, the rise of creatinine is temporary, and the values are expected to return to normal once the medications are discontinued.
  • Intense Physical Activity: The muscles in the human body typically contain creatinine, which helps in the production of energy. However, there is an abnormally high amount of creatinine in the body when an individual goes through intense physical activity.


B. Low Level of Creatinine

Low values of creatinine in the blood are likely a result of the following conditions.

  • Pregnancy: Due to the increase of blood flow to the kidneys, this increases urine production. When urination is frequent, it leads to faster elimination of the byproduct. This rapid elimination of creatinine results in low values it in the blood.
  • Dangerous Weight Loss: Individuals who go to the extremes to lose weight are likely to have less than a reasonable amount of creatinine in the blood. Weight loss results in reduced muscle mass, which directly leads to low creatinine.
  • Low Muscle Mass: Muscle breakdown results in the production of creatinine. However, if there is little muscle mass, then it leads to low values of creatinine. Individuals at risk for low muscle mass include the elderly. Severely malnourished individuals also have low muscle mass as well as low creatinine values. Other conditions such as muscular dystrophy and myasthenia gravis also lead to small amounts of creatinine.


Symptoms of Kidney Dysfunction

Take note that the signs associated with renal insufficiency or kidney dysfunction vary. Moreover, the symptoms do not directly correlate with the creatinine values in the blood. However, here are some manifestations of kidney dysfunction to be aware of.

  • Confusion
  • Dry Skin
  • Edema or Swelling
  • Fatigue
  • Feeling Dehydrated
  • Nausea and Vomiting
  • Neuropathy
  • Shortness of Breath


Factors Affecting Results

Not all tests are final, and the results do not immediately indicate that an individual has kidney or liver damage. Other factors might interfere with the results of a creatinine test. As mentioned above, these include pregnancy, certain medications, overconsumption of protein, and excessive intake of vitamin c.

Speak to your doctor regarding the results. He or she may likely advise further tests to evaluate the health of your kidneys and liver.