# What is my creatinine clearance?

Estimates kidney function from serum creatinine with the 2021 CKD-EPI equation (eGFR), the MDRD Study equation, or Cockcroft-Gault creatinine clearance, with the KDIGO GFR category.

- Page: https://www.acalculator.org/health/creatinine-clearance-calculator
- JSON spec: https://www.acalculator.org/health/creatinine-clearance-calculator.json
- Version: c73a889cbc45

## Default answer

Example with the default inputs (Formula 2021 CKD-EPI (recommended), Serum creatinine 1 mg/dL, Age 50, Sex Male): With the 2021 CKD-EPI (recommended) formula, the result is 92 (eGFR, mL/min/1.73 m²), category G1: normal or high.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| formula | Formula | The equation: 2021 CKD-EPI (recommended), MDRD Study, or Cockcroft-Gault. |
| scr | Serum creatinine | Serum creatinine from the blood test (IDMS-standardized, as US labs report it). |
| age | Age | Age in whole years (adults, 18 and older). |
| sex | Sex | Sex at birth, which the body formulas use. |
| bodyWeight | Weight | Body weight, which Cockcroft-Gault uses. |
| bodyHeight | Height | Height, for the ideal-body-weight versions of Cockcroft-Gault. Optional. |
| isBlack | Black race (MDRD only) | The MDRD Study equation multiplies by 1.212 for Black patients. CKD-EPI 2021 does not use race. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| gfr | Kidney function | eGFR in mL/min/1.73 m² (CKD-EPI, MDRD), or creatinine clearance in mL/min (Cockcroft-Gault), with the KDIGO category. |
| measure | What this number is | Which measure and unit the result is in. |
| stage | KDIGO GFR category | The KDIGO 2012 GFR category (G1 to G5) for the result. |
| idealWeight | Ideal body weight | Devine ideal body weight: 50 kg (men) or 45.5 kg (women) + 2.3 kg per inch over 5 feet. |
| crclIdeal | Clearance with ideal weight | Cockcroft-Gault creatinine clearance using ideal body weight, mL/min. |
| crclAdjusted | Clearance with adjusted weight | Cockcroft-Gault using adjusted body weight, ideal + 0.4 × (actual − ideal), mL/min. Often used when weight is over 120% of ideal. |

## Method

CKD-EPI 2021: 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age × 1.012 (women); MDRD: 175 × Scr^−1.154 × age^−0.203 × 0.742 (women) × 1.212 (Black); Cockcroft-Gault: (140 − age) × weight ÷ (72 × Scr) × 0.85 (women). Scr in mg/dL, weight in kg.

## Assumptions

- Creatinine is IDMS-standardized (the MDRD constant 175 assumes this). µmol/L is converted with the creatinine molar mass 113.12 g/mol (1 mg/dL = 88.40 µmol/L).
- CKD-EPI and MDRD give eGFR per 1.73 m² of body surface area. Cockcroft-Gault gives creatinine clearance in mL/min, with actual body weight unless you read the ideal or adjusted rows.
- The categories are the KDIGO 2012 GFR categories. A category of chronic kidney disease also needs the value to last 3 months or more.
- For adults 18 and older with stable creatinine.

## Worked examples

1. formula = ckd-epi, scr = 0.01, age = 50, sex = male gives gfr = 91.691479, stage = G1: normal or high. Source: Inker et al. (2021) CKD-EPI: 142 × (1.0/0.9)^−1.200 × 0.9938^50 = 91.69 mL/min/1.73 m².
2. formula = ckd-epi, scr = 0.006, age = 30, sex = female gives gfr = 123.757864, stage = G1: normal or high. Source: Inker et al. (2021) CKD-EPI: 142 × (0.6/0.7)^−0.241 × 0.9938^30 × 1.012 = 123.76.
3. formula = mdrd, scr = 0.02, age = 60, sex = female, isBlack = no gives gfr = 25.414913, stage = G4: severely decreased. Source: Levey et al. (2006) MDRD: 175 × 2.0^−1.154 × 60^−0.203 × 0.742 = 25.41.
4. formula = cockcroft-gault, scr = 0.012, age = 60, sex = female, bodyWeight = 65, bodyHeight = 1.65 gives gfr = 51.157407, idealWeight = 56.909449, crclIdeal = 44.789844, crclAdjusted = 47.336869. Source: Cockcroft and Gault (1976): (140 − 60) × 65 ÷ (72 × 1.2) × 0.85 = 51.16 mL/min.
5. formula = ckd-epi, scr = 0.015, age = 70, sex = male gives gfr = 49.774777, stage = G3a: mildly to moderately decreased. Source: Inker et al. (2021) CKD-EPI: 132.6 µmol/L × 113.12 g/mol = 1.49997 mg/dL.

## FAQ

### What is creatinine clearance and why is it important?

Creatinine clearance is a measure of how well your kidneys are filtering waste from your blood. Creatinine is a waste product produced by your muscles and filtered out by your kidneys. If your kidneys aren't working properly, creatinine builds up in your blood. This test helps doctors assess kidney function and detect early signs of kidney disease.

### What is a normal eGFR range?

A normal eGFR (estimated Glomerular Filtration Rate) is typically 90 mL/min/1.73m² or higher. Values between 60-89 may indicate mild kidney function loss, while values below 60 for 3 months or more suggest chronic kidney disease. However, eGFR naturally declines with age, so your doctor will interpret results in the context of your age and overall health.

### What should I do if my eGFR is low?

The single most important step is to share and discuss this result with your doctor or another qualified healthcare provider. They can confirm the result with their own tests, investigate the cause of any potential issues, and work with you to create a health plan. It is critical that you do not make any changes to your diet, lifestyle, or medications based solely on the result from this or any other online calculator.

### Can diet and exercise improve my kidney function?

While existing kidney damage usually cannot be reversed, a healthy lifestyle is absolutely essential for protecting your remaining kidney function and slowing the progression of any disease. Key strategies include managing blood pressure and blood sugar, eating a balanced, kidney-friendly diet (which may involve reducing animal protein, sodium, and sugar), staying well-hydrated, and avoiding overuse of certain medications like NSAID pain relievers. Always work with your doctor or a registered dietitian to develop a plan that is safe and effective for your specific situation.

### Why does the calculator need my age and biological sex?

The amount of creatinine your body produces is directly related to your muscle mass, which naturally varies with age and typically differs between biological sexes. By including your age and sex in the calculation, the eGFR formula can provide a much more accurate and personalized estimate of your kidney function than looking at the creatinine blood level alone.

### What is the difference between "Creatinine Clearance" and "eGFR"?

"Creatinine Clearance" (CrCl) is an older method of estimating kidney function. It was either calculated using the Cockcroft-Gault formula or directly measured with a cumbersome 24-hour urine collection process. "eGFR" (estimated Glomerular Filtration Rate) is the modern standard. It is calculated using a more accurate formula (like the 2021 CKD-EPI equation) from a simple blood test. For assessing overall kidney function, eGFR is now considered the more reliable and accurate measure. This calculator gives eGFR by default, and Cockcroft-Gault creatinine clearance when you pick it.

### What is the 2021 CKD-EPI Creatinine Equation?

The 2021 CKD-EPI Creatinine Equation is the most current and recommended formula for estimating glomerular filtration rate (eGFR). It was developed by the Chronic Kidney Disease Epidemiology Collaboration and removes race-based variables to improve equity in care. The National Kidney Foundation recommends it for estimating GFR in adults.

### Why are there warnings for older formulas?

Older formulas like MDRD and Cockcroft-Gault have limitations that make them less reliable for modern clinical use. The MDRD equation included race-based variables that have been removed from current guidelines. The Cockcroft-Gault formula (1976) was developed before modern laboratory standards and can overestimate kidney function, potentially leading to incorrect medication dosing decisions.

### What do the CKD stages mean?

Chronic Kidney Disease (CKD) stages classify kidney function based on eGFR values. KDIGO names the GFR categories G1 to G5. G1 (90 or more) is normal or high, with possible signs of kidney damage. G2 (60-89) is mildly decreased. G3a (45-59) is mildly to moderately decreased and G3b (30-44) moderately to severely decreased. G4 (15-29) is severely decreased, and G5 (under 15) is kidney failure, which may need dialysis or a transplant.

### When should I use the Cockcroft-Gault formula?

The Cockcroft-Gault formula is primarily used for medication dosing adjustments in patients with kidney disease, particularly for drugs that are renally eliminated. However, it should be used with caution as it can overestimate kidney function. The 2021 CKD-EPI equation is preferred for general kidney function assessment and CKD staging.

### What units should I use for creatinine?

This calculator accepts both mg/dL (common in the US) and µmol/L (common internationally); for µmol/L, type the unit after the number, for example 88 µmol/L. The calculator converts µmol/L to mg/dL with the molar mass of creatinine (113.12 g/mol), so 1 mg/dL is 88.40 µmol/L. Use the units that match your laboratory results for the most accurate calculation.

### How accurate are these calculations?

The 2021 CKD-EPI equation works well for most adults with stable kidney function. However, these are estimates and should be interpreted in clinical context. Factors like muscle mass, diet, medications, and acute illness can affect creatinine levels and eGFR accuracy. Always consult with healthcare professionals for clinical decisions.

### Can I use this calculator for children?

No, this calculator is designed for adults (age 18 and older). The formulas used are validated for adult populations. Pediatric kidney function assessment requires different equations that account for age-related changes in muscle mass and body composition. Consult with pediatric nephrology for children's kidney function assessment.

### What factors can affect my creatinine levels?

Creatinine levels can be influenced by muscle mass, diet (especially meat consumption), medications (like trimethoprim, cimetidine), dehydration, and acute illness. High muscle mass can increase creatinine without indicating kidney disease, while low muscle mass can mask kidney dysfunction. This is why eGFR calculations include age and sex variables.

### How often should I check my kidney function?

The frequency depends on your health status and risk factors, such as diabetes, high blood pressure, a family history of kidney disease, or known CKD. Follow your healthcare provider's recommendations for monitoring frequency.

## Sources

- Inker LA, Eneanya ND, Coresh J, et al. New creatinine- and cystatin C-based equations to estimate GFR without race. N Engl J Med. 2021;385(19):1737-1749. https://doi.org/10.1056/NEJMoa2102953
- National Kidney Foundation, CKD-EPI Creatinine Equation (2021). https://www.kidney.org/ckd-epi-creatinine-equation-2021
- Levey AS, Coresh J, Greene T, et al. Using standardized serum creatinine values in the Modification of Diet in Renal Disease Study equation for estimating glomerular filtration rate. Ann Intern Med. 2006;145(4):247-254. https://doi.org/10.7326/0003-4819-145-4-200608150-00004
- Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41. https://doi.org/10.1159/000180580
- Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650-655 (ideal body weight).
- Winter MA, Guhr KN, Berg GM. Impact of various body weights and serum creatinine concentrations on the bias and accuracy of the Cockcroft-Gault equation. Pharmacotherapy. 2012;32(7):604-612. https://doi.org/10.1002/j.1875-9114.2012.01098.x
- KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int Suppl. 2013;3(1):1-150 (GFR categories G1 to G5).