Three kidney-function estimates against one label thresholdLive current inputs
Health & Fitness
Kidney Function Dose Planning Calculator
Compare 2021 CKD-EPI indexed eGFR, de-indexed eGFR, and Cockcroft-Gault creatinine clearance against an entered medication-label threshold while leaving the actual drug and dose decision to the authoritative label and clinician.
Indexed CKD-EPI eGFR—
De-indexed CKD-EPI estimate—
Cockcroft-Gault CrCl estimate—
Equation spread—
Estimated body surface area—
Threshold relationship—
Sensitivity result—
Required next step—
Equation comparison gauges
Three kidney-function estimates against one label threshold
Independent gauges show indexed eGFR, de-indexed eGFR, and Cockcroft-Gault clearance; the shared threshold line makes disagreement impossible to hide.
Equation audit
Method, units, threshold margin, and sensitivity cases
The table identifies what each estimate represents and whether creatinine variation changes its side of the entered threshold.
| Method | Central result | Units | Margin to threshold | Sensitivity range |
|---|
Dosing check setup
Start with the drug label, not the calculator
- Identify the exact medicine, formulation, indication, and authoritative labeling.
- Determine which kidney-function method and units the label uses.
- Enter contemporaneous age, creatinine, height, and the clinically selected weight.
- Compare estimates when the result is near a cutoff.
- Have the prescribing or pharmacy team make the dose decision.
Method mismatch
Two correct equations can cross the same cutoff differently
Indexed eGFR, de-indexed eGFR, and Cockcroft-Gault clearance are not interchangeable labels for one number. Body size and equation design create real differences.
NIDDK recommends additional care near critical dosing cutoffs and notes that combined creatinine-cystatin C estimation may improve accuracy. The page therefore reports disagreement rather than hiding it.
Equation comparator
Calculate each method honestly instead of relabeling one result
CKD-EPI returns an indexed eGFR. Mosteller BSA converts it to an absolute estimate. Cockcroft-Gault uses age, weight, sex factor, and creatinine. None is silently chosen as the dosing answer.
Detailed calculation process and general formulas
eGFR_idx = CKD-EPI-2021(SCr, age, sex)BSA = sqrt(height_cm x weight_kg / 3600)eGFR_abs = eGFR_idx x BSA / 1.73CrCl_CG = ((140-age) x weight) / (72 x SCr) x f_CGmargin_method = estimate_method - thresholdSymbols, meanings, and units
- eGFR_idx
- indexed CKD-EPI estimatemL/min/1.73 m2
- eGFR_abs
- de-indexed CKD-EPI estimatemL/min
- CrCl_CG
- Cockcroft-Gault creatinine clearance estimatemL/min
- f_CG
- Cockcroft-Gault sex factor; 0.85 if femaledimensionless
- threshold
- user-entered label comparison linemL/min
Safety audit
Four items to verify before a renal-dose decision
A numerical threshold is only one part of the instruction.
Correct method
—Confirm the equation named or supported by the medication label.
Correct units
—Indexed and absolute values must not be compared without recognizing their units.
Stable biomarker
Rapidly changing creatinine can invalidate steady-state estimating assumptions.
Full patient context
Dialysis, transplant, pregnancy, extremes of body composition, interactions, and indication can change the decision.
Decision takeaway: When methods disagree near the cutoff, escalate verification rather than averaging the estimates.
Applied decisions
Where dosing errors begin
Small body surface area
Indexed eGFR is de-indexed for a person below 1.73 square meters.
What the result clarifies: The absolute estimate falls and may approach the comparison threshold.
Creatinine near a cutoff
A ten-percent sensitivity allowance moves one equation across the label line.
What the result clarifies: The output calls for verification rather than selecting a dose.
Worked default scenario
Current-input substitution and reconciliation
Method references
Evidence used to frame this specific model
Scope and limitations
This calculator never recommends, changes, withholds, or schedules a medication dose. Drug labels differ, kidney function may be unstable, and weight selection in Cockcroft-Gault requires clinical judgment. Consult the prescriber or pharmacist.
Kidney Function Dose Planning Calculator | Renal Dosing Equation Comparator FAQ
Which equation should I use for dosing?
Use the method supported by the relevant drug label and clinical team; there is no universal answer for every medicine.
Why not average the three estimates?
They estimate different quantities and averaging has no general dosing justification.
Does this handle dialysis?
No. Dialysis dosing requires drug-specific timing and professional guidance.
Why show creatinine sensitivity?
It reveals whether a threshold conclusion is fragile, not a statistical confidence interval.