Doctors often use a creatinine test to determine the function of your kidneys. Having high levels of creatinine in the urine or blood may indicate that the kidneys are not filtering the blood effectively. It may be a sign of a serious health issue, such as Chronic Kidney Disease.

What is Creatinine?

Creatinine is a chemical produced by the muscle due to wear and tear. It usually passes through the bloodstream and filtered through the kidneys and is removed through the urine. Creatine forms when protein is converted into energy through metabolization. It becomes creatinine when it’s broken down. The creatinine level in your blood can be used to measure overall kidney function. Having high levels of creatinine in the blood can indicate kidney disease, since impaired kidney function cannot properly filter waste products such as creatinine.

If you have high creatinine levels, you may be at risk of uremia, a sign of end-stage renal disease (ESRD). Uremia is a buildup of toxins in the blood that occurs when the kidneys stop filtering toxins through the urine. If left untreated, uremia can result in serious health problems or death.

Normal range of Creatinine

What makes creatinine unique is that it is produced at a constant rate, making them at equilibrium in your body. When the kidneys are damaged, they become less efficient in filtering waste materials such as creatinine. This indicates the amount of creatinine in the blood usually increases.

Creatinine levels are different based on different factors including age, gender, and body size. Two tests are used to determine kidney function, the serum creatinine test and the creatinine clearance test.

Serum Creatinine Test

The serum creatinine test measures the creatinine level in the blood. It is a common blood test that doesn’t require any preparation. This test is often used as a preliminary test to determine kidney health. The serum creatinine levels increase as the kidney function decline, indicating a kidney problem long before any other symptoms of CKD start to appear.

Doctors will use other lab test results to calculate your Glomerular Filtration Rate (GFR) and determine your kidney function more accurately. GFR is the kidney’s filtration rate, or the speed at which your kidneys can filter waste from your blood.

Serum creatinine is measured by the milligrams (mg) of creatinine per deciliter (dL) of your blood. The normal levels range between:

• 0.6 - 1.2 mg/dL for adult males
  
• 0.5 - 1.1 mg/dL for adult females
  

Creatinine Clearance Test

On the other hand, a creatinine clearance test is an older test used to evaluate how your kidneys can remove creatinine from your bloodstream. It involves the collection of urine over 24 hours and then a blood test. These samples are used to check how much creatinine was filtered through the kidneys over the 24-hour window.

As the creatinine clearance test needs urine and blood sample collected within 24 hours, this test involves more preparation compared to a serum creatinine test. Nevertheless, a creatinine clearance test is a much more precise estimate of actual kidney function.

Creatinine clearance is measured in milliliters (ml) of blood filtered per minute (min). The normal levels range between:

• 97 - 137 ml/min for males

• 88 - 128 ml/min for females

Creatinine Levels Chart

As mentioned, creatinine levels are determined by different factors. However, normal blood creatinine levels are:

• Men: 0.6 to 1.2 mg/dL; 53 to 106 mmol/L

• Women: 0.5 to 1.1 mg/dL; 44 to 97 mmol/L

• Teenagers: 0.5 to 1.0 mg/dL

• Children: 0.3 to 0.7 mg/dL

On the other hand, normal urine creatinine levels are:

• Men: 107 to 139 mL/min; 1.8 to 2.3 mL/sec
• Women: 87 to 107 mL/min; 1.5 to 1.8 mL/sec
• Any person >40 years of age: Levels should drop by 6.5 mL/min for every additional 10 years of age

Check this creatinine levels chart below to understand your kidney function better:

Causes of high levels of Creatinine

Having high creatinine levels can indicate a sign of kidney disease. Symptoms may include changes in quantity and frequency of urine, changes in the appearance of urine and blood in the urine. Factors that can increase the levels of creatinine include:

• Specific medications such as antibiotics, Non-steroidal anti-inflammatory drugs ( NSAIDs) 

• Creatine supplements or those containing creatine as an ingredient

• Dietary factors including high protein consumption

• strenuous exercise

• Declined kidney function

• Low blood flow

• Dehydration

• Infections

• Cancer

If your lab test shows a high creatinine level, your doctor may order further tests to determine the cause.

Foods to Lower Creatinine

Dietary treatment is an essential aspect of managing Chronic Kidney Disease along with proper medication. It is important to meet a renal dietitian or talk to your nephrologist to discuss your unique dietary needs.

A Journal of Renal Nutrition study in March 2014 shared that foods with added fiber can lower creatinine levels among CKD patients. The study found that the serum creatinine levels of 13 CKD patients declined after consuming fiber-rich foods for two weeks. 

According to National Kidney Function (NKF), it is important to limit potassium and phosphorus consumption to lower creatinine levels. Here are a few of the foods you can consume instead to help manage your creatinine and CKD:

The Bottomline

High creatinine levels in the blood when you have CKD should be addressed properly to help manage the decline of kidney function. A great way to manage high levels of creatinine is through diet by consuming foods that are low in potassium and phosphorus as well as monitoring the amount of protein consumed. Consuming the foods suggested above may help lower creatinine levels.

Nevertheless, it is always best to check in with your nephrologist and renal dietitian for customized medications and dietary plans, respectively.