Kidney Failure Risk Calculator (KFRE)
Calculation Method
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Fractional Excretion of Magnesium
About this Calculator
The Fractional Excretion of Magnesium (FEMg) calculator is a crucial tool for assessing renal magnesium handling, particularly in patients with hypomagnesemia. In normal physiological conditions, the kidneys should conserve magnesium when plasma levels are low. This calculator helps clinicians determine whether magnesium losses are occurring through the kidneys or other routes.
In patients with hypomagnesemia:
- An FEMg above 3-4% indicates renal magnesium wasting, suggesting that the kidneys are inappropriately excreting magnesium despite low serum levels.
- An FEMg below 2% usually points to an extrarenal source of magnesium loss, typically gastrointestinal.
Research has shown that in hypomagnesemic patients, those with extrarenal causes of magnesium depletion had a mean FEMg of 1.4% (range 0.5-2.7%), while those with renal magnesium loss had a mean FEMg of 15% (range 4-48%).
FEMg (%) = Urine Mg / Serum Mg Urine Cr / Serum Cr × 100
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Fractional Excretion of Sodium (FENa)
About this Calculator
The Fractional Excretion of Sodium (FENa) calculator is a useful tool for assessing kidney function, particularly in differentiating between prerenal and intrinsic renal causes of acute kidney injury. FENa is calculated using the concentrations of sodium and creatinine in both urine and serum. This calculator allows you to input these values and select the appropriate units for creatinine measurements, providing a quick and accurate FENa percentage.
FENa (%) = Urine Na / Serum Na Urine Cr / Serum Cr × 100
Possible Interpretation of Results
FENa < 1%: This typically indicates a prerenal cause of acute kidney injury, where the kidneys are conserving sodium due to decreased blood flow or volume depletion. Common causes include dehydration, heart failure, or cirrhosis.
FENa 1-2%: This range can be seen in both prerenal and intrinsic renal conditions, and further clinical correlation is needed to determine the underlying cause.
FENa > 2%: This suggests an intrinsic renal cause of acute kidney injury, where the kidneys are unable to reabsorb sodium effectively. Common causes include acute tubular necrosis, interstitial nephritis, or glomerulonephritis.
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Kt/V Dialysis Dose Daugirdas Formula
About this Calculator
The Kt/V Dialysis Dose Daugirdas Formula is an essential tool for evaluating the adequacy of dialysis treatment. It provides a quantitative measure of dialysis efficiency by assessing the removal of urea from the blood. This formula is widely used by clinicians to ensure that patients receive the appropriate dialysis dose to maintain optimal health.
In dialysis treatment:
- A higher Kt/V value indicates more effective dialysis, suggesting that a greater amount of urea is being removed from the blood.
- A lower Kt/V value may indicate inadequate dialysis, necessitating adjustments in treatment to improve urea clearance.
The Daugirdas formula is particularly useful for calculating Kt/V in hemodialysis patients, providing a standardized method to assess treatment efficacy.
Kt/VDaugirdas = -ln((BUNPost / BUNPre) - (0.008 * Hours)) + ((4 - (3.5 * BUNPost / BUNPre)) * UFVol / WeightPost)
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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.
Creatinine clearance estimate by Cockcroft-Gault equation in adults and older adolescents (age ≥16 years) (SI units)
About this Calculator
The Creatinine Clearance calculator using the Cockcroft-Gault equation is a valuable tool for estimating kidney function in adults and older adolescents (age ≥16 years). This calculator provides an estimate of creatinine clearance, which is an important indicator of renal function. It takes into account age, weight, sex, and serum creatinine levels to produce an estimate of creatinine clearance in mL/min.
The Cockcroft-Gault equation used in this calculator is:
CrCl = Sex Factor * (140 - Age) * Weight * 1.23 Serum Creatinine
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