Lab marker · High

High Cystatin C: what it means

A Cystatin C result above the normal range is considered high. Here is what a raised Cystatin C can point to, and when it is worth discussing with a doctor.

Reference range: Adults 0.5–1.0 mg/L; rises with renal impairment. Independent of muscle mass — preferred in elderly, paediatric, amputees, body-builders.

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What a high Cystatin C can mean

  • Chronic kidney disease — every CKD stage from G1 onward.
  • Acute kidney injury — rises faster than creatinine after a renal insult.
  • Untreated hyperthyroidism, high-dose corticosteroids — small non-renal upward influence.
  • Older age — physiological GFR decline of ~1 mL/min/1.73 m² per year after 40.

When to discuss with a doctor

Order cystatin C when serum creatinine may mislead — elderly + frail patients, body-builders, paediatric, post-amputation, very low muscle mass (e.g. cachexia), or when an unexpected creatinine result needs confirmation before a drug dose decision (chemo, contrast, vancomycin). Also useful pre-transplant donor screening. Mediora.AI computes cystatin-C-based eGFR when both creatinine and cystatin C are present; CKD staging and management is nephrology.

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Mediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.