80-Year-Old female — GFR & CKD Stage
Estimate based on a typical serum creatinine of 1.0 mg/dL. Use the calculator below to enter your own lab result.
Estimated GFR
57.0 mL/min/1.73m²
Example
A 80-year-old woman with a serum creatinine of 1 mg/dL has an estimated GFR of 57.0 mL/min/1.73m² (CKD-EPI 2021), corresponding to Stage 3a (Mildly to moderately decreased).
CKD Stage
Stage 3a
Description
Mildly to moderately decreased
MDRD Comparison
53.3 mL/min/1.73m²
Formula Used
CKD-EPI 2021
Where your GFR falls among CKD stages
What Is GFR?
The glomerular filtration rate (GFR) describes how fast fluid is filtered through the tiny filtering units of your kidneys, called glomeruli. It's the single most widely used measure of overall kidney function — a higher value means your kidneys are clearing waste more effectively.
Rather than measuring GFR directly (which requires an invasive clearance test), doctors estimate it from a routine blood test for serum creatinine, combined with age, sex, and — in some older equations — race. Normal GFR runs roughly 100–130 mL/min/1.73m² in men and 90–120 in women under 40, gradually declining with age even in healthy kidneys.
| Stage | GFR Range | Description |
|---|---|---|
| Stage 1 | 90+ | Normal or high kidney function |
| Stage 2 | 60–89 | Mildly decreased kidney function |
| Stage 3a (you) | 45–59 | Mildly to moderately decreased |
| Stage 3b | 30–44 | Moderately to severely decreased |
| Stage 4 | 15–29 | Severely decreased kidney function |
| Stage 5 | 0–14 | Kidney failure |
How Is GFR Estimated?
This calculator uses the 2021 CKD-EPI creatinine equation for adults — the current standard recommended by the National Kidney Foundation and American Society of Nephrology since 2021, which removed the race adjustment used in earlier versions to improve accuracy and equity across patient populations. For children under 18, it uses the bedside Schwartz formula, which relies on height instead of an adult-specific age curve.
Why Race Was Removed From the Equation
Earlier equations (including the original CKD-EPI and MDRD formulas) included a coefficient that increased the estimated GFR for patients identified as Black, based on average differences in creatinine generation observed in older study populations. Clinical bodies determined this coefficient risked delaying diagnosis and specialist referral for Black patients, so the race-free 2021 equation — used here — is now the recommended standard.
Why the MDRD Comparison Figure Differs
The MDRD equation was developed from an older, sicker study population and tends to underestimate GFR at higher (healthier) values compared to CKD-EPI, which is why the two figures shown here can diverge, especially for GFR values above 60.
What Affects GFR Besides Kidney Disease
Serum creatinine — and therefore estimated GFR — is also affected by muscle mass, recent heavy exercise, high protein intake, dehydration, and certain medications, so a single abnormal result usually calls for a repeat test rather than an immediate diagnosis.
Example — Your Current Inputs
A 80-year-old woman with a serum creatinine of 1 mg/dL has an estimated GFR of 57.0 mL/min/1.73m² (CKD-EPI 2021), corresponding to Stage 3a (Mildly to moderately decreased).
Additional Example — Elevated Creatinine
A 65-year-old woman with a serum creatinine of 1.4 mg/dL has an estimated GFR of about 42 mL/min/1.73m², placing her in Stage 3b (moderately to severely decreased kidney function) — a result that typically prompts referral to a nephrologist for further evaluation.
About These Parameters
- Serum Creatinine
- The core input, taken directly from a routine metabolic panel blood test. Even small differences in this value meaningfully shift the estimated GFR.
- Age & Gender
- Both factor into the equation because average muscle mass and creatinine production differ by age and sex, independent of actual kidney function.
- Height (children only)
- Used only when age is under 18, where the Schwartz formula substitutes height for the adult-specific age and sex terms.
Frequently Asked Questions
Is a lower GFR always a serious problem?
GFR naturally declines with age even in healthy adults, and CKD is typically only diagnosed when reduced GFR persists for three months or more, often alongside other markers like protein in the urine.
Can I improve my GFR?
Managing underlying causes — blood pressure, diabetes, and avoiding nephrotoxic medications where possible — can slow or sometimes partially reverse decline, though established kidney damage is often not fully reversible.
Should I see a doctor about this result?
This calculator is an estimate for educational purposes, not a diagnosis. Any GFR below 60 sustained over time, or any concerning trend, should be discussed with a physician who can order confirmatory testing.