eGFR Calculator (MDRD/CKD-EPI)

Glomerular filtration rate (GFR) is the amount of blood filtered by the kidneys’ glomeruli each minute. It is one of the key measures of kidney function. Because measuring true GFR directly is complex, many labs report an estimated GFR (eGFR) calculated from creatinine, age, sex and other factors. According to Wikipedia’s article on GFR, eGFR is widely used to stage chronic kidney disease and to monitor kidney function over time.

Doctors use eGFR alongside creatinine, urine tests and clinical findings to see whether kidney function is normal, mildly reduced or more seriously impaired. Because many medications are cleared by the kidneys, understanding approximate filtration rate is also important when adjusting doses or planning imaging tests that use contrast agents. The eGFR Calculator helps you see how the underlying formulas generate the number you see on your lab report.

The tool accepts serum creatinine together with age, sex and (in some versions) race or ethnicity where the published equations originally included it. After you click “Calculate eGFR”, the script applies one or more standard formula sets, typically:

• MDRD (Modification of Diet in Renal Disease) equation.
• CKD-EPI equation (one of the most commonly used modern formulas).

For each selected equation, the calculator displays an eGFR value in mL/min/1.73 m², along with a neutral comment indicating whether the result falls into a broadly normal or reduced range from an educational perspective. It does not override the value reported by your laboratory; rather, it helps you understand how different equations can produce slightly different estimates.

The emphasis is on transparency and learning: the tool uses fixed equations described in medical literature and reminds you that individual labs may implement updated or local variations of these formulas.

eGFR equations share several core ideas:

• Creatinine-based estimation – Creatinine is a waste product filtered by the kidneys; higher creatinine usually means lower filtration.
• Adjustment for age and sex – Muscle mass and creatinine generation differ between people, so formulas adjust for age and sex to improve accuracy.
• Normalised to 1.73 m² – Results are often expressed per 1.73 m² body surface area to allow comparison between individuals.
• Limitations at extremes – Very unusual muscle mass, extreme diets or acute illness can make any creatinine-based estimate less accurate.

The eGFR Calculator does not attempt to replace measured GFR in complex cases; it simply reproduces recognised equations so you can see how your reported eGFR is derived from your creatinine and demographics.

To see how eGFR relates to other kidney markers, you may also find the Kidney Function Analyzer and the Creatinine Clearance Calculator useful companions as you review your results.

Using the eGFR Calculator is straightforward:

• Open your lab report and locate your serum creatinine value and its unit.
• Select the correct unit on the tool (for example, mg/dL or µmol/L) if this option is available.
• Enter your age and select your sex exactly as requested by the calculator.
• Choose which equations to apply (MDRD, CKD-EPI, or both).
• Click the “Calculate eGFR” button and review the resulting numbers and notes.

You can try different creatinine values (for example from older reports) to see how eGFR trends over time. This can help you prepare questions for your next appointment, but treatment decisions must always be based on your doctor’s interpretation, not on the calculator alone.

When discussing kidney function over the long term, clinicians may also consider markers shown in the CMP Analyzer or specific kidney function panels available on labscan.cloud.

eGFR is most informative when interpreted alongside other kidney and metabolic markers. On labscan.cloud, the following tools complement the eGFR Calculator:

• Kidney Function Analyzer – provides an educational interpretation of creatinine, BUN and related markers.
• Creatinine Clearance (CrCl) Calculator – illustrates how 24-hour urine collections or Cockcroft–Gault type estimates relate to filtration.
• Electrolytes Analyzer – helps you understand sodium, potassium and other ions that kidneys help regulate.

Together, these tools support a clearer, more structured view of renal function while keeping diagnosis and treatment firmly in the hands of your healthcare team.

Which eGFR formula is “best” for me?
Different guidelines favour different equations, and many laboratories have moved toward newer CKD-EPI variants. Your own lab report usually states which method it uses. The calculator shows several options for learning, not to override your lab’s choice.

Does a low eGFR automatically mean I have chronic kidney disease?
Not on its own. eGFR must be interpreted together with how long it has been reduced, urine findings, imaging and clinical context. Only a clinician can diagnose chronic kidney disease.

Can I rely on this calculator instead of my lab’s eGFR?
No. Laboratory systems use validated, calibrated methods. The online calculator is a teaching aid that uses published equations but may not mirror every local adjustment or version.

Is this tool suitable for children, pregnancy or acute illness?
No. Standard adult equations have important limitations in children, pregnant individuals and people with rapidly changing kidney function. Specialised methods are required in those settings.

By combining the eGFR Calculator with other analyzers on labscan.cloud, you can gain a more transparent understanding of how your kidney function is estimated—while leaving final diagnosis and management decisions to your healthcare professionals.