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Blood sugar & kidneys

eGFR

Estimated GFR (cystatin C)

An estimate of kidney filtration function - a quiet but important marker that often changes long before symptoms appear.

General reference≥ 90mL/min/1.73m²
What it is

The basics

Estimated glomerular filtration rate (eGFR) is a calculation, not a direct measurement, of how much blood your kidneys filter each minute. This panel estimates it from cystatin C, a small protein that the body’s cells produce at a steady rate and the kidneys clear, using the CKD-EPI cystatin C equation. Because cystatin C is largely independent of muscle mass, it can give a more reliable estimate than creatinine, particularly in people with very high or very low muscle mass.

What it tells you

Why this marker matters

eGFR is the workhorse marker of kidney function. Because chronic kidney disease usually progresses silently - without symptoms until late - eGFR is one of the few ways to catch a problem early. A persistent decline below 60 mL/min/1.73 m² over more than three months meets the formal criterion for chronic kidney disease, and warrants a closer look.

Reference range

Where the typical ranges sit

≥ 90 mL/min/1.73 m² normal; 60–89 mildly decreased; < 60 indicates kidney disease if persistent.

KDIGO categories: G1 ≥ 90 normal or high; G2 60–89 mildly decreased; G3a 45–59 mildly to moderately decreased; G3b 30–44 moderately to severely decreased; G4 15–29 severely decreased; G5 < 15 kidney failure. Mild decreases in older adults can be physiological rather than disease.

Reference ranges differ between laboratories and guidelines. Your CHIRAYOU report uses the range reported by the analysing laboratory, and your interpretation should be discussed with a physician.

What affects it

Common influencers

  • Age (kidney function declines gradually with age)
  • Hydration status (acute dehydration can transiently lower eGFR)
  • Thyroid function (cystatin C rises in overactive and falls in underactive thyroid)
  • Systemic corticosteroids (can raise cystatin C independent of kidney function)
  • Diabetes and high blood pressure (the two leading causes of CKD)
  • Smoking, obesity, and inflammation (can modestly raise cystatin C)
When to follow up

If your value is outside the range

A first abnormal eGFR should be confirmed with a repeat in a few weeks, ideally combined with a urine albumin/creatinine ratio. Persistent reduction below 60 - and any single result below 45 - should be reviewed with a physician. Modifiable factors like blood pressure control matter substantially for long-term kidney health.

Sources

Where this comes from

Measure your eGFR from home.

Order the blood test

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