What is Creatinine?

Creatinine is a waste product generated from the digestion of protein in your food and the normal wear and tear of muscles in the body. It's produced from creatine, a molecule of major importance for energy production in muscles. Once created, creatinine is transported through the bloodstream to the kidneys, where it is filtered out of the blood and excreted in urine.

The measurement of creatinine levels in the blood offers vital insights into kidney function. This is because the kidneys are responsible for filtering creatinine out of the blood. If the kidneys are damaged or not functioning properly, blood creatinine levels can rise due to decreased filtration. Therefore, creatinine tests are crucial in assessing renal function and detecting kidney disease.

Why is Creatinine Important?

Creatinine levels are a reliable indicator of kidney health for several reasons:

  • Kidney Function Assessment: High levels of creatinine in the blood often suggest impaired kidney function or kidney disease. Since the kidneys filter and remove creatinine from the bloodstream, elevated levels can indicate that the kidneys are not working effectively.
  • Disease Progression and Monitoring: For individuals diagnosed with kidney disease, monitoring changes in blood creatinine levels can help assess the progression of the disease and the effectiveness of treatment strategies.
  • Guiding Treatment: In certain medical conditions, such as chronic kidney disease (CKD), accurate measurement of creatinine levels is essential for making informed decisions about treatment and management, including the need for dialysis.

Understanding Your Creatinine Test Results

Creatinine is measured in milligrams per deciliter (mg/dL) in blood and milligrams per 24 hours (mg/24 h) in urine. The normal range for blood creatinine levels varies depending on age, gender, and muscle mass, and different labs have different reference ranges. According to the American Board of Internal Medicine, serum creatinine levels are:

  • Adult males: Approximately 0.70 to 1.30 mg/dL
  • Adult females: Approximately 0.50 to 1.10 mg/dL

Higher muscle mass might result in higher creatinine levels; thus, levels can vary widely among individuals. It's crucial to interpret these levels within the context of eGFR (estimated glomerular filtration rate) and other kidney function tests for a comprehensive assessment of renal health.

If you have kidney damage, aiming for lower creatinine levels is recommended. The following tips from UCLA Health are easy lifestyle modifications that may help with lowering creatinine levels and avoiding further kidney damage:

  • Limiting meat intake can help lower creatinine because the most potent source of its precursor, creatine, is meat.
  • Incorporating more high-fiber foods into your diet has been shown in several studies to lower serum creatinine levels.
  • Staying hydrated is important as dehydration can raise creatinine levels.
  • To maintain kidney health, quitting tobacco, limiting sodium intake, and avoiding NSAIDs can minimize renal strain.

Where Can I Learn More?

American Kidney Fund - Avoid the superfood trap: Tips to improve your creatinine and eGFR

UCLA Health - High creatinine levels can indicate chronic kidney disease

Scientific Literature:

    Abcar AC, Chan L, Yeoh H. What To Do for the Patient with Minimally Elevated Creatinine Level? Perm J. 2004 Winter;8(1):51-3. doi: 10.7812/TPP/03-119. PMID: 26704606; PMCID: PMC4690708.

    Ma Q, Gao Y, Lu J, Liu X, Wang R, Shi Y, Liu J, Su H. The effect of regular aerobic exercise on renal function in patients with CKD: A systematic review and meta-analysis. Front Physiol. 2022 Sep 26;13:901164. doi: 10.3389/fphys.2022.901164. PMID: 36225309; PMCID: PMC9549134.