What is creatinine?
Creatinine is a chemical waste product of creatine, an amino acid made by the liver and stored in the liver. Creatinine is the result of normal muscle metabolism. The chemical enters your bloodstream after it’s broken down. Your kidneys remove it from your blood. The creatinine then exits the body through urination.
This process helps your body maintain a normal creatinine level. But sometimes, routine blood or urine tests can reveal low (or high) levels of creatinine.
Normal levels vary according to your body size and muscle mass. For example, a normal range for men is between 0.6 and 1.2 mg/dl and a normal range for women is between 0.5 and 1.1 mg/dl.
The symptoms that go with low creatinine levels depend on the underlying condition. Low creatinine levels can be caused by:
- A muscle disease, such as muscular dystrophy. Symptoms of a muscle disease include muscle weakness, muscle stiffness and pain, and decreased mobility.
- A liver disease. Poor liver function interferes with creatine production, which can cause low creatinine. Symptoms include jaundice, abdominal pain and swelling, and pale, bloody, or tar-colored stools.
- Excess water loss. Pregnancy, excess water intake, and certain medications can cause this.
Since the breakdown of muscle tissue produces creatinine, low levels of this chemical waste often occur in people with low muscle mass. However, this doesn’t always mean there’s a serious medical problem.
A reduction in muscle mass is common in older individuals, as most people lose muscle mass as they age. Low muscle mass can also result from malnutrition, or from eating a low-meat or low-protein diet.
The causes of low creatinine differ from the causes of high creatinine. Creatinine levels also play a role in assessing kidney function. When creatinine begins to accumulate in the body, doctors have to run tests to check for kidney problems.
Possible causes of a higher creatinine level include:
If you have high creatinine levels, symptoms may include:
- changes in urination
- high blood pressure
- chest pains
- muscle cramps
Your doctor can use multiple tests to check your creatinine level. One option is a serum creatinine test, which measures the amount of creatinine in your bloodstream. Another option is a creatinine urine test.
If your lab results confirm a low creatinine level, your doctor may suggest more testing to rule out a muscular disease. This may include a muscle biopsy or a muscle enzyme test to check for muscle damage.
Treatment options for low creatinine depend on the underlying cause. If you have a muscular disease, treatment focuses on treating the related condition and reducing muscle pain, weakness, and degeneration. Options include corticosteroids to improve your muscle strength or therapy to improve your quality of life.
Low creatinine levels due to pregnancy should normalize after giving birth.
If you’re taking a medication that contributes to a lower level, talk to your doctor about adjusting your dosage or switching to another medication.
Low muscle mass treatments
If an underlying medical condition isn’t responsible for a reduction in muscle mass, medical treatment may not be necessary. But your doctor may recommend steps to increase your muscle mass and normalize your creatinine level.
Increasing your level of physical activity and doing strength training exercises a few days a week can increase muscle mass. Talk to your doctor before starting a new exercise program. You can try:
- weight lifting
If your doctor believes low muscle mass results from improper nutrition or extreme weight loss, adjust your diet. Make sure you’re eating five to six small, healthy meals per day. Include a mixture of fruits and vegetables as well as protein-rich foods.
The outlook is generally positive for people who have low creatinine levels, as long as they receive necessary treatment for any underlying medical condition. If further testing rules out a muscle disease, your doctor may suggest lifestyle and diet changes and then retest your level at a later time. With the proper adjustments, your levels should normalize.