GFR Calculator

Calculate Your GFR

Welcome to the GFR (Glomerular Filtration Rate) Calculator! The GFR is a crucial indicator of how well your kidneys are functioning. By measuring your GFR, doctors can evaluate your risk of developing chronic kidney disease (CKD) or monitor the progression of existing kidney conditions. This calculator uses the CKD-EPI formula, one of the most widely accepted methods for estimating GFR.

Input Your Details

Example: Enter your serum creatinine level in mg/dL (e.g., 1.2).
Example: Enter your age in years (e.g., 45).

Understanding GFR

Glomerular Filtration Rate (GFR) is a key indicator of kidney function. It estimates how much blood your kidneys are filtering per minute, measured in milliliters per minute per 1.73m² of body surface area. A lower GFR indicates reduced kidney function, and it is used to diagnose and stage chronic kidney disease (CKD).

Why is GFR Important?

GFR is used by doctors to assess kidney health. A normal GFR ranges from 90 to 120 mL/min/1.73m², and lower levels indicate potential kidney dysfunction. A declining GFR can be an early sign of kidney disease, which, if untreated, may lead to kidney failure.

What Affects GFR?

Several factors influence GFR, including:

  • Age: GFR naturally declines with age, even in people without kidney disease.
  • Gender: Males typically have higher GFRs than females due to differences in muscle mass and body size.
  • Race: People of African descent may have slightly different GFR values due to genetic factors, which is why the CKD-EPI formula adjusts for race.
  • Serum Creatinine Levels: Higher levels of creatinine in the blood typically indicate poorer kidney function, lowering GFR.

What Do GFR Results Mean?

Your GFR result will fall into one of the following categories, which correspond to the stages of chronic kidney disease (CKD):

  • GFR ≥ 90 mL/min/1.73m²: Normal or high kidney function. No CKD or stage 1 CKD if other markers of kidney damage are present.
  • GFR 60-89 mL/min/1.73m²: Slightly reduced kidney function (stage 2 CKD). May not require immediate treatment, but regular monitoring is necessary.
  • GFR 30-59 mL/min/1.73m²: Moderately reduced kidney function (stage 3 CKD). Requires medical management to slow the progression of the disease.
  • GFR 15-29 mL/min/1.73m²: Severely reduced kidney function (stage 4 CKD). Often indicates the need for preparing for dialysis or kidney transplant.
  • GFR < 15 mL/min/1.73m²: Kidney failure (stage 5 CKD). Requires dialysis or kidney transplant for survival.

How is GFR Calculated?

GFR is calculated using various formulas, but the most common and accurate for adults is the CKD-EPI formula, which accounts for age, gender, race, and serum creatinine levels. The CKD-EPI formula is generally considered more precise than other formulas like the MDRD equation, especially for higher GFR values.

CKD-EPI Formula

The CKD-EPI formula used in this calculator is:

GFR = 141 × min(SCr/k, 1) ^ α × max(SCr/k, 1) ^ -1.209 × 0.993 ^ age × race_factor

Where:

  • SCr: Serum creatinine level in mg/dL
  • k: Constant based on gender (0.9 for males, 0.7 for females)
  • α: Constant based on gender (-0.411 for males, -0.329 for females)
  • race_factor: 1.159 for Black individuals, 1.0 for others

Who Should Use a GFR Calculator?

This GFR Calculator is especially useful for individuals who:

  • Have high blood pressure or diabetes, which are major risk factors for kidney disease.
  • Are over the age of 60, as kidney function declines naturally with age.
  • Have a family history of kidney disease.
  • Are taking medications that can affect kidney function.
  • Want to monitor their kidney health as part of regular check-ups.

Conclusion

Understanding your GFR is critical for managing kidney health. Whether you're at risk for kidney disease or simply want to stay on top of your health, this GFR Calculator offers an easy way to estimate your kidney function. Regularly monitoring your GFR can help you and your healthcare provider detect potential kidney issues early and take steps to prevent further damage.