Cystatin C Test Results Meaning for Kidney Function
The cystatin C test results meaning reflects how efficiently your kidneys filter blood using this sensitive biomarker. Normal levels are typically 0.62–1.15 mg/L, with higher values indicating reduced filtration and possible early kidney disease. Unlike creatinine, cystatin C is less affected by muscle mass or diet. It is widely used to calculate eGFR and detect early kidney dysfunction.
Contents
Result interpretation Cystatin C
What your result means based on common reference ranges
Cystatin C levels within range indicate normal kidney filtration and stable renal function without signs of chronic kidney disease.
Mildly elevated cystatin C levels suggest early kidney dysfunction or reduced glomerular filtration rate in chronic kidney disease.
Significantly high cystatin C levels indicate advanced kidney impairment with reduced filtration capacity and increased risk of renal failure.
Low cystatin C levels may reflect hypothyroidism or altered protein production rather than improved kidney filtration function.
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What is Cystatin C?
Cystatin C is a small protein produced by all nucleated cells and cleared almost exclusively by the kidneys. Its blood level closely reflects glomerular filtration rate (GFR), making it a reliable marker in a kidney blood test. Unlike creatinine, it is not significantly influenced by muscle mass, age, or diet, improving accuracy in elderly or lean individuals. Elevated cystatin C levels are associated with chronic kidney disease, diabetes, and hypertension. It is commonly used alongside creatinine, eGFR, and urine albumin to provide a comprehensive view of kidney function and early renal impairment.
Reference ranges
Causes of abnormal values
Causes of low Cystatin C
- • Hypothyroidism — reduced metabolic activity lowers protein production
- • Severe liver disease — impaired protein synthesis affects cystatin C levels
- • Chemotherapy — decreased cell turnover reduces protein generation
Causes of high Cystatin C
- • Chronic kidney disease — reduced filtration causes cystatin C accumulation in blood
- • Diabetes mellitus — glomerular damage impairs filtration efficiency
- • Hypertension — vascular damage reduces kidney perfusion and filtration
- • Hyperthyroidism — increased metabolism raises cystatin C production
- • Corticosteroid therapy — stimulates protein production independent of kidney function
- • Systemic inflammation — cytokines increase production and alter clearance
Cystatin C in combination with other markers
Possible symptoms
- •Peripheral edema (ankles, feet, hands)
- •Persistent fatigue
- •Foamy urine (proteinuria)
- •Nocturia (frequent night urination)
- •Metallic taste in mouth
When to see a doctor
Consult a doctor if cystatin C levels exceed 1.15 mg/L or eGFR drops below 60 mL/min. Seek evaluation if elevated levels persist or are accompanied by swelling, fatigue, or high blood pressure. Repeated abnormal results require assessment for underlying kidney disease or metabolic conditions.
What to do if abnormal
- Maintain proper hydration with water daily
- Monitor blood pressure and keep it within target range
- Control blood sugar if diabetes is present
- Review medications that may affect kidney function
- Repeat cystatin C blood test in 3–6 months
The information on this page is intended for general understanding of test results and does not replace medical consultation. Accurate interpretation requires considering other blood markers and individual factors.
Content is based on medical literature and used within the PulseBook analytical system.
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