Summary

Cystatin C is a valuable biomarker used to assess kidney function. Unlike creatinine, which is a byproduct of muscle metabolism, cystatin C is a protein produced by all nucleated cells in the body. It is removed from the bloodstream solely by the kidneys. Its measurement provides a more accurate estimation of glomerular filtration rate (GFR), a key indicator of kidney function, and can aid in diagnosing and monitoring renal health.

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Overview

Cystatin C is an essential biomarker for evaluating kidney function, offering distinct advantages over creatinine. While high creatinine levels may result from various factors, including diet and muscle mass, cystatin C levels are less influenced by these variables, making it a superior marker for GFR assessment.

As a reliable marker of kidney function, cystatin C is utilized to calculate GFR, offering valuable insights into renal health. If your cystatin C blood levels are too high, it may indicate your kidneys aren’t working properly. Unlike creatinine, cystatin C is not affected by muscle mass, gender, or age, making it particularly useful in diverse populations. Cystatin C levels remain relatively stable over time, allowing for consistent monitoring of kidney function.^[1-3]

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What should you know about this biomarker?

Cystatin C levels are typically measured in blood samples. Reference ranges may vary slightly between laboratories due to differences in measurement techniques. 

In general, the optimal level of cystatin C is considered to be 0.55-1.15 mg/l (milligrams per liter) in people between the ages of 1-50 years. And 0.63-1.44 mg/l for people over 50 years of age. Deviations from this range can indicate potential kidney dysfunction.^[4]

There are three possible states of your blood test result: low, average, and high levels.

• Cystatin C levels below the reference limit are generally not concerning. However, consulting a healthcare professional is advisable for further evaluation. 
• Optimal cystatin C levels indicate healthy kidney function. Regular monitoring is still recommended, especially for individuals with risk factors for kidney disease.
• Elevated cystatin C levels suggest impaired kidney function. It is crucial to consult a physician for a comprehensive evaluation and appropriate management.

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Genetics

Genetic factors contribute to the regulation of cystatin C levels, similar to creatinine. Scientific investigations have revealed a hereditary component and identified specific genetic variations, known as single nucleotide polymorphisms (SNPs), linked to lower cystatin C levels. Notably, research has focused on polymorphisms within the CST3 gene in connection to this phenomenon.^[5,6] However, the influence of genetics is still being investigated, and ongoing studies continue to uncover additional insights.

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Recommendations

If cystatin C levels deviate from the optimal range, it may indicate potential kidney issues. Consider these steps to improve your kidney health effectively:

• Adjust your diet to promote kidney health. Limiting the intake of processed foods and excessive protein may benefit cystatin C levels.
• Maintain proper hydration to support kidney function and ensure accurate cystatin C measurements.
• If elevated cystatin C levels persist, your doctor may order additional tests to diagnose and determine the extent of kidney dysfunction.
• If prescribed medications for kidney-related conditions, adhere to the prescribed regimen as directed by your healthcare provider.
• Engage in regular moderate exercise, as it indirectly supports kidney function and overall well-being.^[7] 

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The information and tests provided on our website are for educational purposes only and are not a substitute for professional medical advice. Always consult with your healthcare provider before making health decisions. Our tests do not diagnose or treat diseases. Individual results may vary and should be discussed with a healthcare provider.