Kidney Failure Risk Calculator (KFRE)
Calculation Method
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Body mass index (BMI) calculator
About this Calculator
The Body Mass Index (BMI) calculator is a widely used tool for assessing body weight relative to height. It provides a simple numerical measure that helps categorize individuals into different weight status categories, such as underweight, normal weight, overweight, and various classes of obesity. This calculator is a valuable resource for both clinicians and individuals to evaluate health risks associated with body weight.
BMI Categories:
- Below normal weight: BMI less than 18.5
- Normal weight: BMI 18.5–24.9
- Overweight: BMI 25–29.9
- Class I Obesity: BMI 30–34.9
- Class II Obesity: BMI 35–39.9
- Class III Obesity: BMI 40 or greater
While BMI is a useful screening tool, it does not directly measure body fat or account for muscle mass, bone density, and overall body composition. Therefore, it should be used in conjunction with other assessments for a comprehensive evaluation of an individual's health.
BMI = Weight (kg) Height (m)2
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Urine osmolal gap (UOG)
About this Calculator
The Urine Osmolar Gap calculator is a valuable tool used to assess the difference between the measured and calculated osmolality of urine. This gap can provide important insights into the presence of unmeasured solutes in the urine, which can be crucial for diagnosing various metabolic and renal disorders. Clinicians often use this calculator to evaluate conditions such as renal tubular acidosis, intoxications, and other electrolyte imbalances.
Understanding the Urine Osmolar Gap:
- Normal osmolar gap: Typically less than 10 mOsm/kg
- Increased osmolar gap: May indicate the presence of unmeasured solutes such as alcohols, sugars, or other substances
While the urine osmolar gap is a useful diagnostic tool, it should be interpreted in the context of a comprehensive clinical evaluation. Factors such as hydration status, medication use, and underlying health conditions can influence the results and should be considered when assessing the osmolar gap.
Urine Osmolar Gap = Measured Urine Osmolality (mOsm/kg) Calculated Urine Osmolality (mOsm/kg)
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Glomerular Filtration Rate Estimation (eGFR) ≤25 Years Old
About this Calculator
The estimated Glomerular Filtration Rate (eGFR) calculator is an essential tool for assessing kidney function, particularly in children and young adults up to 25 years old. It provides a numerical estimate of how well the kidneys are filtering waste from the blood. This calculator uses both serum creatinine and cystatin C levels, along with age, sex, and height, to provide a more accurate estimation of kidney function compared to using creatinine alone.
eGFR Categories for Children and Young Adults:
- Normal or High: eGFR 90 mL/min/1.73 m² or higher
- Mildly Decreased: eGFR 60-89 mL/min/1.73 m²
- Mildly to Moderately Decreased: eGFR 45-59 mL/min/1.73 m²
- Moderately to Severely Decreased: eGFR 30-44 mL/min/1.73 m²
- Severely Decreased: eGFR 15-29 mL/min/1.73 m²
- Kidney Failure: eGFR less than 15 mL/min/1.73 m²
This eGFR calculator uses equations from the Chronic Kidney Disease in Children (CKiD) study, which are specifically designed for pediatric and young adult populations. It's important to note that while eGFR is a valuable screening tool, it should be used in conjunction with other clinical assessments for a comprehensive evaluation of kidney function.
eGFR by Creatinine = KCreat × (Height / 100) / Serum Creatinine
eGFR by Cystatin C = KCysC / Serum Cystatin C
Average eGFR = (eGFR by Creatinine + eGFR by Cystatin C) / 2
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Arterial Blood Gas Interpretation Calculator
About this Calculator
Understanding the physiological principles behind acid-base balance and interpreting the results based on the provided code is crucial. Here's a step-by-step tutorial on how to use this calculator to analyze acid-base disorders:
Analyzing Acid-Base Disorders Using the Arterial Blood Gas (ABG) Calculator
Step 1: Gather Patient Data
Before using the calculator, collect the following patient data:
- pH: Indicates the acidity or alkalinity of the blood
- PaCO₂: Partial pressure of carbon dioxide, reflecting respiratory function
- HCO₃⁻: Bicarbonate level, indicating metabolic function
- Sodium (Na⁺), Chloride (Cl⁻), and Albumin: Electrolytes used to calculate the anion gap
Step 2: Input Validation
Ensure that the input values fall within the physiological ranges:
- pH: 6.8 to 7.8
- PaCO₂: 15 to 130 mmHg
- HCO₃⁻: 3 to 45 mEq/L
- Sodium: 110 to 170 mEq/L
- Chloride: 70 to 130 mEq/L
- Albumin: 0.1 to 7 g/dL
Step 3: pH Analysis
- Acidemia: pH < 7.35
- Alkalemia: pH > 7.45
- Normal pH: 7.35 ≤ pH ≤ 7.45
Step 4: Primary Disorders
Metabolic Disorders
- Metabolic Acidosis: HCO₃⁻ < 22 mEq/L
- Expected PaCO₂ = (1.5 × HCO₃⁻) + 8
- Check respiratory compensation
- Metabolic Alkalosis: HCO₃⁻ > 26 mEq/L
- Expected PaCO₂ = (0.7 × (HCO₃⁻ − 24)) + 40
- Check respiratory compensation
Respiratory Disorders
- Respiratory Acidosis: PaCO₂ > 45 mmHg
- Acute: HCO₃⁻ ↑ by 1 per 10 mmHg PaCO₂ ↑
- Chronic: HCO₃⁻ ↑ by 3.5 per 10 mmHg PaCO₂ ↑
- Respiratory Alkalosis: PaCO₂ < 35 mmHg
- Acute: HCO₃⁻ ↓ by 2 per 10 mmHg PaCO₂ ↓
- Chronic: HCO₃⁻ ↓ by 5 per 10 mmHg PaCO₂ ↓
Final Steps
Step 5: Compensation Status
- Evaluate if compensation is appropriate
- Check for mixed disorders
Step 6: Anion Gap
- Calculate: Na⁺ − (Cl⁻ + HCO₃⁻)
- Correct for albumin if needed
- Normal range: 8-12 mEq/L
Step 7: Final Interpretation
Combine all findings to form complete assessment
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Kidney failure risk equation (KFRE) Calculator
About the KFRE Calculator
The Kidney Failure Risk Equation (KFRE) Calculator is a vital tool for predicting the risk of progression to kidney failure in patients with chronic kidney disease (CKD). By utilizing key clinical variables, this calculator helps healthcare providers make informed decisions about patient management and treatment strategies.
The KFRE Calculator provides a standardized approach to assess disease progression risk in CKD patients, enabling evidence-based clinical decision-making.
Kidney Failure Risk Equation
KFRE = 1 - exp(-exp(X))
where X = (0.220 × Age) + (0.246 × Male) + (0.451 × eGFR) + (0.556 × Albuminuria) - 1.957
Kidney Disease Risk Assessment
| GFR Categories (ml/min/1.73m²) | A1 Normal to mildly increased <30 mg/g <3 mg/mmol | A2 Moderately increased 30-299 mg/g 3-29 mg/mmol | A3 Severely increased ≥300 mg/g ≥30 mg/mmol | |
|---|---|---|---|---|
| G1 | Normal or high ≥90 | |||
| G2 | Mildly decreased 60-89 | |||
| G3a | Mildly to moderately decreased 45-59 | |||
| G3b | Moderately to severely decreased 30-44 | |||
| G4 | Severely decreased 15-29 | |||
| G5 | Kidney failure <15 | |||
Low risk
Moderately increased risk
High risk
Very high risk
References
- 1. Tangri N, Stevens LA, Griffith J, et al. A predictive model for progression of chronic kidney disease to kidney failure. JAMA. 2011;305(15):1553-1559. doi:10.1001/jama.2011.451
- 2. Tangri N, Grams ME, Levey AS, et al. Multinational Assessment of Accuracy of Equations for Predicting Risk of Kidney Failure: A Meta-analysis. JAMA. 2016;315(2):164-174. doi:10.1001/jama.2015.18202
- 3. Lennartz CS, Pickering JW, Seiler-Mußler S, et al. External Validation of the Kidney Failure Risk Equation and Re-Calibration with Addition of Ultrasound Parameters. Clin J Am Soc Nephrol. 2016;11(4):609-615. doi:10.2215/CJN.08110815
- 4. Major RW, Shepherd D, Medcalf JF, Xu G, Gray LJ, Brunskill NJ. The Kidney Failure Risk Equation for prediction of end stage renal disease in UK primary care: An external validation and clinical impact projection cohort study. PLoS Med. 2019;16(11):e1002955. doi:10.1371/journal.pmed.1002955
- 5. Peeters MJ, van Zuilen AD, van den Brand JA, et al. Validation of the kidney failure risk equation in European CKD patients. Nephrol Dial Transplant. 2013;28(7):1773-1779. doi:10.1093/ndt/gft063
- 6. KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int Suppl. 2013;3(1):1-150.
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