Screening and diagnosis

Classification and risk stratification

Perioperative care

Quality improvement

Patient education

Nonpharmacologic interventions

Therapeutic procedures

Respiratory support

Follow-up and surveillance

Specific circumstances

Preventative measures

Medical management

Surgical interventions

Inpatient care

Diagnostic procedures

Diagnostic investigations

Insufficient evidence to make a recommendation.

Strongly favor this test or intervention.

The 2021 CKD-EPI Creatinine-Cystatin C calculator is designed to estimate an individual's kidney function through the calculation of the estimated glomerular filtration rate (eGFR) and to assign a chronic kidney disease (CKD) stage based on key health parameters. By inputting a person's age, gender, serum creatinine, and cystatin C levels, the calculator determines their eGFR and corresponding CKD stage. Here is how it works:

- **Serum Creatinine**: This is initially adjusted to mg/dL if provided in µmol/L, using a straightforward conversion: creatinine (mg/dL) = creatinine (µmol/L) / 88.4.
  
- **Gender-Specific Parameters**: The calculator uses different parameters for males and females due to physiological differences:
  - For females:
    - A = 0.7
    - B depends on whether creatinine is ≤ 0.7 (value -0.219) or > 0.7 (value -0.544)
    - C = 0.8
    - D depends on whether cystatin C is ≤ 0.8 (value -0.323) or > 0.8 (value -0.778)
  - For males:
    - A = 0.9
    - B depends on whether creatinine is ≤ 0.9 (value -0.144) or > 0.9 (value -0.544)
    - C = 0.8
    - D depends on whether cystatin C is ≤ 0.8 (value -0.323) or > 0.8 (value -0.778)

- **Calculating eGFR**: With these values, the eGFR is calculated using the formula:
  \( eGFR = 135 \times (creatinine / A)^B \times (cystatin C / C)^D \times 0.996^{\text{age}} \)
  If the individual is female, this result is further adjusted by multiplying the calculated eGFR by 0.963 to account for differences in muscle mass and body composition.

- **CKD Stage Interpretation**:
  - eGFR ≥ 90 indicates Stage 1 (Normal or High renal function)
  - eGFR 60-89 indicates Stage 2 (Mildly Decreased function)
  - eGFR 45-59 indicates Stage 3a (Moderately Decreased function)
  - eGFR 30-44 indicates Stage 3b (Moderately Decreased function)
  - eGFR 15-29 indicates Stage 4 (Severely Decreased function)
  - eGFR < 15 indicates Stage 5 (Kidney Failure)

By evaluating the inputs of age, gender, creatinine, and cystatin C levels, this calculator yields a rounded eGFR and a concise assessment of kidney health through the assigned CKD stage. This interpretation aids in diagnosing and managing potential kidney health issues, based on recognized medical guidelines.

The 2021 CKD-EPI Creatinine-Cystatin C equation combines both serum creatinine and cystatin C measurements to estimate GFR. This combination provides improved accuracy over single-marker equations, especially in patients where creatinine-based estimates alone may be less reliable.

CKD-EPI Creatinine-Cystatin C Equation for eGFR (2021)

The 2021 CKD-EPI Creatinine equation is a useful tool for estimating the kidney's filtering ability, known as the estimated glomerular filtration rate (eGFR). This measure is central to understanding kidney health and staging chronic kidney disease (CKD). Three inputs are needed: the person's age, gender, and serum creatinine level.

Here's how it works:

Inputs include the person's age, gender, and serum creatinine level. Age is provided as a whole number between 18 and 90 years. Gender options are "Male" or "Female." Serum creatinine levels can be entered in mg/dL (ranging from 0.1 to 20) or in µmol/L (ranging from 8.84 to 1768.4), with an internal conversion done to ensure units are in mg/dL for consistency.

The computation begins with a gender-dependent factor (A), which is 0.7 for females and 0.9 for males. Next, depending on whether the creatinine level is below or above this threshold, a second factor (B) is determined: for creatinine levels below or equal to the threshold, B is -0.241 for females and -0.302 for males; for levels above, B is -1.2 regardless of gender.

Using these factors, the eGFR is calculated with the formula: 
eGFR = 142 * (creatinine / A)^B * (0.9938^age)

Additionally, for females, the eGFR is multiplied by 1.012 for final adjustment. 

Once the eGFR is determined, it is rounded to a whole number and used to classify the CKD stage, reflecting the degree of kidney function:

- Stage 1 (Normal or High) is an eGFR of 90 or above
- Stage 2 (Mildly Decreased) spans 60 to under 90
- Stage 3a (Moderately Decreased) encompasses 45 to under 60
- Stage 3b (Moderately Decreased) covers 30 to under 45
- Stage 4 (Severely Decreased) ranges from 15 to under 30
- Stage 5 (Kidney Failure) is under 15

These stages provide critical insights into kidney health, potentially guiding clinical decisions and management.

The 2021 CKD-EPI creatinine equation estimates Glomerular Filtration Rate (eGFR) using serum creatinine, age, and sex. This updated version removed race as a variable to provide more equitable care across populations. It's currently recommended by KDIGO guidelines for routine clinical practice.

CKD-EPI Creatinine Equation for eGFR (2021)

The MDRD GFR Equation calculator helps estimate how well your kidneys are filtering blood, expressed as the estimated glomerular filtration rate (eGFR). This measurement reflects kidney function and helps determine stages of chronic kidney disease (CKD). To use this calculator, you'll need to know four things: gender, age, serum creatinine level, and race.

Serum creatinine levels, integral to the calculation, must first be standardized. If your creatinine level is provided in micromoles per liter (µmol/L), convert it to milligrams per deciliter (mg/dL) by dividing by 88.4. This ensures that all calculations are consistent.

With this information, the MDRD formula estimates the eGFR: 

- eGFR = 175 × (creatinine^(-1.154)) × (age^(-0.203))

Specific adjustments are made to this calculation for certain demographics:
- Multiply the result by 0.742 if you are female. This accounts for differences in muscle mass, as women generally have less muscle mass compared to men.
- Multiply by 1.212 if you are Black, as studies have shown distinct genetic factors that influence kidney function.

After computing the eGFR, the value is rounded to the nearest whole number. This final figure places you in one of the CKD stages, each reflecting a range of kidney function:

- Stage 1: eGFR of 90 or more, indicating normal kidney function with some kidney damage.
- Stage 2: eGFR between 60 to 89, suggesting mild decrease in kidney function.
- Stage 3a: eGFR between 45 to 59, indicating a mild to moderate decrease.
- Stage 3b: eGFR between 30 to 44, showing a moderate to severe decrease.
- Stage 4: eGFR between 15 to 29, indicating severely reduced function.
- Stage 5: eGFR less than 15, which is considered kidney failure.

This estimation assists healthcare providers in understanding kidney health over different stages, guiding treatment decisions and health management.

The MDRD GFR Equation estimates the Glomerular Filtration Rate (eGFR) using serum creatinine, age, gender, and race, adjusted for body surface area. It is widely used for early detection of Chronic Kidney Disease (CKD) and provides an accurate assessment of kidney function without requiring urine collection, making it practical for routine clinical use.

MDRD GFR Equation

The 2009 CKD-EPI Creatinine calculator is a tool used to estimate the glomerular filtration rate (GFR), which helps assess kidney function and determine the stage of chronic kidney disease (CKD). It takes into account several personal health factors to deliver a meaningful result.

Inputs include:
- Age, which should be a numerical value between 18 and 120 years.
- Gender, for which the options are "male" or "female."
- Serum Creatinine, given in either mg/dL (0.1 to 20) or μmol/L (1 to 1000). If provided in μmol/L, the tool converts this to mg/dL using a factor of 0.0113.
- Race, which can be "black" or "non-black" to account for race-related physiological differences.

In determining the estimated GFR, the calculator performs the following steps:
- Identifies parameters based on gender. Females use a kappa of 0.7 and an alpha of -0.329, while males use a kappa of 0.9 and an alpha of -0.411.
- It calculates the estimated GFR using a formula that incorporates these parameters, the age of the individual, and adjustments for gender and race.
- The calculation follows a specific formula: 141 multiplied by the function of serum creatinine levels over kappa, raised to the power of alpha, adjusting for the individual's age, gender, and race.

The results are:
- Estimated GFR in mL/min/1.73 m², rounding to the nearest whole number. This estimate reflects kidney filtration efficiency, with possible values ranging from 0 to 150.
- CKD Stage, which provides a clear understanding of kidney health:
  - Stage 1, indicating normal or high kidney function with a GFR of 90 or more.
  - Stage 2, mild reduction in function with GFR between 60 and 89.
  - Stage 3, moderate reduction with GFR between 30 and 59.
  - Stage 4, severe reduction with GFR between 15 and 29.
  - Stage 5, suggesting kidney failure with GFR below 15.

This method allows clinicians and patients to assess kidney health systematically, using key health metrics to guide potential management and treatment decisions.

The CKD-EPI equation estimates Glomerular Filtration Rate (GFR) using serum creatinine, age, sex, and race. It's more accurate than the MDRD equation, especially at higher GFR values, and is the current standard for estimating kidney function in clinical practice.

CKD-EPI Creatinine (2009)

The Creatinine Clearance (Cockcroft-Gault Equation) calculator estimates kidney function through the creatinine clearance rate, reflecting how effectively the kidneys filter waste. This tool requires input on age, gender, weight, height, and serum creatinine level.

Key parameters:
- Age (years): 18 to 120
- Gender: Male or Female
- Weight: in kilograms (20–200 kg) or pounds (44–440 lbs)
- Height: in centimeters (120–220 cm) or inches (48–87 in)
- Creatinine: in mg/dL (0.1–20) or µmol/L (8.84–1768.4)

The process involves:

1. **Unit Conversion**:
   - Convert weight from pounds to kilograms, if necessary, using 1 kg = 2.20462 lbs.
   - Convert height from centimeters to inches, if necessary, using 1 inch = 2.54 cm.
   - Convert creatinine from µmol/L to mg/dL, if necessary, using 1 mg/dL = 88.4 µmol/L.

2. **Ideal Body Weight (IBW) Calculation**:
   - For males: IBW = 50 + 2.3 * (height in inches - 60)
   - For females: IBW = 45.5 + 2.3 * (height in inches - 60)

3. **Adjusted Body Weight (ABW) Calculation**:
   - ABW = IBW + 0.4 * (actual weight - IBW)

4. **Creatinine Clearance Calculation**:
   - Original CrCl (using actual weight): ((140 - age) * weight) / (72 * creatinine)
   - IBW CrCl (using ideal weight): ((140 - age) * IBW) / (72 * creatinine)
   - ABW CrCl (using adjusted weight): ((140 - age) * ABW) / (72 * creatinine)

5. **Gender Adjustment**:
   - For females, each calculated CrCl value needs multiplying by 0.85.

Final outputs include:
- Original CrCl, reflecting estimation with actual weight.
- IBW CrCl, using ideal weight.
- ABW CrCl, calculated with adjusted weight.
- Weight used for the computation, displayed in kilograms.

These outputs, rendered in mL/min and rounded to one decimal place, facilitate the assessment of kidney function and inform clinical decisions regarding medication dosing. Better kidney filtration capabilities correspond to higher clearance scores, guiding clinicians in interpreting renal health.

The Cockcroft-Gault equation calculates creatinine clearance to estimate kidney function and guide medication dosing. It considers age, weight, gender, and serum creatinine, incorporating adjustments for body weight when necessary. This widely-used formula helps healthcare providers assess renal function and adjust medication doses accordingly.

Creatinine Clearance (Cockcroft-Gault Equation)

The BUN/Creatinine Ratio is a clinical calculator used in the field of nephrology and internal medicine. BUN stands for Blood Urea Nitrogen, a waste product generated in the liver and excreted by the kidneys, while Creatinine is a waste product produced by muscle metabolism and also excreted by the kidneys. 

This ratio is primarily used to differentiate between prerenal and renal causes of acute kidney injury (AKI). A high BUN/Creatinine ratio (>20:1) is typically suggestive of a prerenal cause such as dehydration or decreased blood flow to the kidneys, while a low ratio (<10:1) is more indicative of intrinsic renal disease or postrenal obstruction. 

The BUN/Creatinine Ratio is applicable to patients with suspected kidney disease or injury, or those with known renal conditions where monitoring of renal function is necessary. It is also used in the evaluation of patients with altered mental status or suspected metabolic disorders. 

There are no specific exclusion criteria for the use of the BUN/Creatinine ratio, but it should be interpreted with caution in patients with liver disease, malnutrition, or those on certain medications that can affect BUN or creatinine levels. It is also important to note that this ratio is

Membranoproliferative glomerulonephritis

Guidelines

Key sources

Diagnostic investigations

Medical management