Cystatin C details
What Cystatin C shows
Cystatin C is a protein produced by essentially all cells in the body at a fairly steady rate, and — unlike creatinine — its blood level isn't significantly affected by muscle mass, age, sex, or diet, which makes it a useful alternative or complementary marker of kidney function in situations where creatinine might be misleading (very muscular or very frail people, for example). It's filtered by the kidneys similarly to creatinine, so an elevated level likewise indicates reduced kidney filtering capacity. Some labs use cystatin C alone or combined with creatinine to calculate a more precise eGFR, particularly useful for detecting early kidney function decline that a creatinine-based estimate alone might miss.
Normal ranges
Typical adult range
0.5–1 mg/L
Most labs report a range close to this
Hormunity optimal range
0.62–0.9 mg/L
A narrower functional target
Each lab sets its own reference range. Always compare your result with the range printed on your report, and review it with a healthcare provider.
Tests that include Cystatin C
Cystatin C is a protein produced by all nucleated cells that is filtered by the kidneys. It serves as a sensitive and early marker of kidney function, often providing a more accurate assessment of glomerular filtration rate (GFR) than creatinine, especially in certain populations.
- Cystatin C An alternative marker of kidney function that, unlike creatinine, isn't affected by muscle mass — useful for a more precise eGFR estimate.
This test measures the level of Cystatin C, a protein found in your body fluids, to assess kidney function. Unlike other markers, the level of Cystatin C's in the blood does not change due to infections, diet, or medication, making it a reliable indicator of how well your kidneys are filtering. The test also estimates your Glomerular Filtration Rate (eGFR), which indicates the rate at which your kidneys are filtering the blood. It's especially useful for people with unusual muscle mass or rapidly changing kidney function.
- Cystatin C An alternative marker of kidney function that, unlike creatinine, isn't affected by muscle mass — useful for a more precise eGFR estimate.
- Estimated GFR An estimate of how well your kidneys filter blood, calculated here from cystatin C along with factors such as age and sex.
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