Skip to content

Cystatin C

Published: July 27, 2026Updated: August 25, 2026

Cystatin C is a protein produced by all nucleated cells and is used to assess kidney function. It is particularly useful in estimating glomerular filtration rate (eGFR).

Quick summary

Cystatin C is a reliable biomarker for evaluating kidney function and detecting early renal impairment.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
mg/L
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche Cystatin C, Abbott Cystatin C, Siemens Cystatin C
interpretation: {"text":"0.5–1.0 mg/L: Indicates normal kidney function.","label":"Normal"}; {"text":">1.0 mg/L: Suggests potential kidney dysfunction and may require further evaluation.","label":"Elevated"}

Cystatin C is a small protein molecule produced by all nucleated cells at a constant rate. It is freely filtered by the glomerulus and serves as an endogenous marker of kidney function.

Unlike creatinine, cystatin C is less influenced by muscle mass, age, and gender, making it a more accurate indicator of renal function in certain populations.

Elevated levels of cystatin C in the blood can indicate decreased kidney function, even when creatinine levels are still within the normal range.

Frequently asked questions

What is the advantage of measuring cystatin C over creatinine?
Cystatin C is less affected by muscle mass and diet, providing a more accurate assessment of kidney function in diverse populations.
Can cystatin C levels be affected by other conditions?
Yes, conditions such as thyroid dysfunction and inflammation can influence cystatin C levels, so results should be interpreted with caution.
  1. 1
    Cystatin C as a Marker of GFR—History, Indications, and Future ResearchSource
  2. 2
    Understanding Cystatin C: A Better Marker of Kidney Function?Source

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy