Creatinine is a chemical waste molecule that is produced when muscles use creatine (another naturally occurring product in the body) to create energy. About 2% of creatine is converted to creatinie each day. Most of the waste creatinine is expelled from the body in the urine. The creatinine level measured for an individual should be relatively constant over time and should be within a “normal” range. However, you should pay attention to creatinine level that is too high or too low because that could mean there are problems with your kidney.

Normal Creatinine Levels

Why is the creatinine level important? The creatinine level is one of the main indicators of kidney function. If the creatinine level is elevated, your healthcare provider will look for other signs of kidney disease and renal problems.

Creatinine levels are measured in milligrams (1 mg=1/1000 of a gram) and deciliters (1 dl=1/10 of a liter). Normal creatinine level ranges will depend on age, gender and other health factors. The “normal” range may also be slightly different depending on the lab where it is measured.

• Adult Males. The normal range of creatinine in a healthy adult male is 0.6 to 1.2 mg/dl. Creatinine levels higher than 10.0 indicate very severe kidney disease. A measurement above 8.0 will prompt your healthcare provider to run additional tests.
• Adult Females. The normal range of creatinine in a healthy adult female is 0.5 to 1.1 mg/dl. Again, creatinine levels higher than 10.0 indicate very severe kidney disease.
• Infants. Since creatinine levels are a function of muscle usage and development, the normal range for an infant will start at 0.2 mg/dl and will range up from that point depending on how well developed the infant is. A creatinine level at 2.0 mg/dl or higher in an infant would indicate severe kidney disease or failure.
• Individuals with One Kidney. An individual who has had a kidney removed may have a normal creatinine level of 1.8 or 1.9 mg/dl.
• Special Circumstances. Very muscular adults may have higher creatinine levels than their less muscular peers. As muscle mass diminishes with age, the elderly may have creatinine levels that are lower than other adults. In any disease that results in muscle wasting (e.g., malnutrition, chronic illnesses, and rapid weight loss), the creatinine level may be low for the individual’s age and gender.

Tests to Measure Kidney Function

If your healthcare provider suspects you may have decreased renal function, she will probably order lab tests that might include blood urea nitrogen (BUN) level, a creatinine level and a BUN/Creatinine ratio. With diminished kidney function, creatinine and BUN levels will both increase.

Watch a video for three tests to measure kidney function: Creatinine, BUN and BUN/Creatinine:

Abnormal Creatinine Levels

1. High Creatinine Levels

Causes: High creatinine levels can be caused by anything that decreases the function of the kidneys. There are acute and chronic causes of changes in the creatinine level. Two of the most significant and common causes of chronic kidney disease are diabetes and hypertension. Muscle building can lead to elevated creatinine levels. Chemotherapy drugs are known to cause high creatinine levels. Finally, an individual with a diet high in red meat may have slightly elevated creatinine levels.

Symptoms: Symptoms of kidney disease and elevated creatinine are variable and, in fact, some individuals may not have any symptoms at all. Extreme thirst and tiredness may be early symptoms. Swelling of the extremities and shortness of breath may also be symptoms of a kidney disorder. Mental changes and confusion are usually late symptoms of kidney problems.

Treatments: Treatment of kidney disease as evidenced by a high creatinine level is based on determining the underlying cause and living a generally healthy lifestyle.

• Treat the Underlying Condition. First, if your creatinine level is elevated, your healthcare provider will run the lab tests and may repeat them to ensure that the first levels were correct. If hypertension or diabetes is the cause of the problem, your doctor will want to treat these aggressively with medications and monitoring. Catching the problem early will help prevent irreversible kidney damage.
• Avoid Smoking and Alcohol. It is critical to stop or reduce smoking and alcohol use. Both of these substances are known to damage blood vessels throughout your body including your kidneys and renal system. Your healthcare provider will undoubtedly recommend that you stop smoking and drinking if your creatinine levels are high.
• Eat Right. Proteins in the diet should be limited and should be very high quality. The diet should contain high levels of vitamins (especially A, B2 and C) and low levels of salt – particularly if hypertension is the cause of the elevated creatinine. Your healthcare provider should refer you to a nutritionist to discuss the right diet.

2. Low Creatinine Levels

Causes: Low creatinine levels are typically caused by muscle wasting diseases, chronic liver disease or the normal aging process. A diet very low in protein and pregnancy in women can result in abnormally low creatinine levels. With a low level, there may be no evident symptoms.

Treatments: There are really no specific treatments for abormal creatinine levels that are low. If the cause is a muscle wasting disease, all treatments are aimed at treating the disease and not the creatinine level. In these cases, the healthcare provider may prescribe steroid medications to help slow muscle breakdown. Low creatinine levels associated with pregnancy typically resolve when the pregnancy is over. Individuals who do not eat enough quality protein will be advised to increase their intake of protein.