Estimate kidney filtration rate (eGFR) and identify Chronic Kidney Disease (CKD) stages using the official 2021 CKD-EPI race-free equation, comparative 2009 CKD-EPI & MDRD formulas for adults, and the Bedside Schwartz equation for pediatric patients.
1 mg/dL = 88.42 µmol/L (auto-converted when switching units).
The modern 2021 CKD-EPI standard omits race entirely. Selecting this modifier only affects the legacy 2009 CKD-EPI and MDRD comparison calculations.
A single eGFR calculation does not establish a diagnosis of Chronic Kidney Disease. Persistently reduced eGFR (< 60 mL/min/1.73 m²) or structural kidney markers (albuminuria uACR > 30 mg/g) for ≥ 3 months are required to confirm CKD.
Normal physiological filtration rate. In the absence of urinary markers (such as persistent albuminuria or hematuria) or structural kidney abnormalities, kidney function is fully intact.
Routine annual wellness screening. Maintain blood pressure < 120/80 mmHg, optimal hydration, and regular exercise.
| Nephrology Equation | Calculated eGFR |
|---|---|
CKD-EPI (2021 Race-Free) Current Recommended Standard | 107.3 |
| CKD-EPI (2009 Standard)Includes race coefficient (1.0x) | 102.8 |
| MDRD Study EquationLegacy (4-variable study) | 91.3 |
Chronic Kidney Disease progression and cardiovascular mortality risk depends on both GFR category (G1–G5) and persistent urine Albumin-to-Creatinine Ratio (uACR A1–A3).
| GFR Category (mL/min/1.73m²) | A1: Normal to Mild < 30 mg/g (< 3 mg/mmol) | A2: Moderately Increased 30 – 300 mg/g (3 – 30 mg/mmol) | A3: Severely Increased > 300 mg/g (> 30 mg/mmol) |
|---|---|---|---|
| G1 (Normal or High, ≥ 90) | Low Risk (Treat if other damage) | Moderately Increased Risk | High Risk |
| G2 (Mildly Decreased, 60–89) | Low Risk | Moderately Increased Risk | High Risk |
| G3a (Mild to Moderate, 45–59) | Moderately Increased Risk | High Risk | Very High Risk |
| G3b (Moderate to Severe, 30–44) | High Risk | Very High Risk | Very High Risk |
| G4 (Severely Decreased, 15–29) | Very High Risk | Very High Risk | Very High Risk |
| G5 (Kidney Failure, < 15) | Very High Risk | Very High Risk | Very High Risk |
Glomerular filtration rate is universally acknowledged as the single best overall index of kidney function in health and disease. Below is an exhaustive clinical guide explaining the filtration mechanism, modern equations, guidelines, and diagnostic considerations.
The kidneys contain approximately one million microscopic filtering units called nephrons. Each nephron possesses a tuft of specialized capillaries known as the glomerulus. The Glomerular Filtration Rate (GFR) represents the total volume of fluid filtered from the glomerular capillaries into Bowman's capsule per unit of time (expressed in milliliters per minute: mL/min).
Because kidney size and nephron mass correlate directly with overall physical stature, clinical nephrology normalizes measured or estimated GFR to an average adult Body Surface Area (BSA) of 1.73 m². This yields the standard reporting units of mL/min/1.73 m².
In young, healthy adults (20–29 years old), normal GFR is approximately 115 to 125 mL/min/1.73 m². Starting around age 30 to 40, GFR naturally declines by approximately 0.8 to 1.0 mL/min/1.73 m² per year as part of the normal biological aging process (senescent nephrosclerosis).
Chronic conditions such as diabetic nephropathy, hypertensive glomerulosclerosis, glomerulonephritis, and polycystic kidney disease can accelerate filtration loss to > 5 mL/min/year, leading to dangerous uremic toxin retention.
Answers to common clinical questions regarding lab values, testing frequencies, and lifestyle optimization.