What does Cystatin C mean?
Cystatin C is a protein filtered by the kidneys. It can add a second view of kidney filtration when creatinine is difficult to interpret because of muscle mass or diet.
What it shows and why it matters
Cystatin C is a protein made by most cells and removed from blood by the kidneys. A higher result can indicate lower kidney filtration and can add useful context when Creatinine is hard to interpret because of muscle mass, diet or amputation. It may be used in a validated Cystatin C or combined Creatinine–Cystatin C eGFR equation, but the reported equation remains a separate result.
How Cystatin C appears on your report
Look for Cystatin C. The result is normally shown in mg/L, next to the reference interval used by the laboratory that ran the test.
Note the collection date before you compare it with anything, along with the context that matters for this marker: kidney filtration, thyroid status, inflammation, steroid medicines, smoking, body composition and assay method can affect it. Use the laboratory's validated eGFR equation where one is reported.
Cystatin C range in Australia
Vector shows an assay-dependent contextual tracking band of 0.50–1.00 mg/L for Cystatin C. It is not a universal optimal target or clinical threshold; use the interval printed by the laboratory that performed the test.
This contextual band mirrors the app and the Vector Profile; the performing laboratory’s interval remains authoritative.
Interpretation limits
Cystatin C is not itself an eGFR. Any filtration estimate should use a validated equation reported for the relevant assay and population.
The interval printed beside your result remains the authority for that specimen. Reference intervals, diagnostic thresholds, treatment targets and Vector's tracking bands answer different questions and should not be substituted for one another.
What to read alongside Cystatin C
A single marker rarely explains itself. These results are commonly interpreted together with Cystatin C, and Vector keeps them within reach of each other as your record grows.
When to discuss Cystatin C with a clinician
Discuss a new or persistent abnormal result, reduced urine output, swelling, vomiting, confusion, heart-rhythm symptoms, kidney disease risk or medicines that affect kidney and electrolyte balance.
Tracking Cystatin C over time
One Cystatin C result is a single point. Import the report into Vector, check the extracted value, unit and collection date, and it becomes the start of a series instead — with each later report adding a dated point you can actually compare against.
Further reading
Cystatin C is read the same way every other result on the report is. These two guides cover that method rather than this marker:
- How to read an Australian pathology report — A practical guide to dates, units, reference intervals and the context that belongs beside an Australian pathology result.
- Pathology report reference ranges: what they mean — Understand the laboratory interval, Australian guidance and the product context Vector adds to a result over time.
Common questions
What is a normal Cystatin C range in Australia?
Australia has no nationally harmonised reference interval for Cystatin C, so the range printed on your report varies with the laboratory and assay. Vector shows 0.50–1.00 mg/L as an assay-dependent contextual tracking band, not a universal optimal target or clinical threshold. Always use the interval beside your own result.
How should the Cystatin C tracking band be interpreted?
Vector shows 0.50–1.00 mg/L as an assay-dependent contextual band for Cystatin C. It is not a universal optimal target or clinical threshold. Interpret the result with the performing laboratory's interval, treatment and symptoms.
What unit is Cystatin C reported in on Australian pathology reports?
Cystatin C is usually reported in mg/L on Australian pathology reports. The performing laboratory prints a reference interval in the same unit beside the result, and that interval is the one that governs your individual result.
What can change your Cystatin C result?
Kidney filtration, thyroid status, inflammation, steroid medicines, smoking, body composition and assay method can affect it. Use the laboratory's validated eGFR equation where one is reported.
Sources
- RCPA Manual: Cystatin CAustralian pathology reference for this test and related result context.
- Kidney Health Australia: eGFRAustralian consumer context for kidney filtration and follow-up.
Published 29 August 2026 · Updated 29 August 2026 · Author Vector