What is the CKD-EPI 2021 equation?

CKD-EPI 2021 is the current KDIGO-recommended formula for estimating GFR from serum creatinine. It removed the race coefficient used in older versions and is now the standard in most clinical labs and guidelines.

What eGFR is safe for iodinated contrast?

Most ACR guidelines consider eGFR ≥45 mL/min/1.73 m² generally safe. eGFR 30–44 warrants caution (consider hydration, weigh benefit vs. risk). eGFR <30 is high risk and typically requires nephrology input or alternative imaging.

Does this apply to gadolinium MRI contrast too?

For gadolinium-based contrast agents, the threshold for nephrogenic systemic fibrosis (NSF) risk is generally eGFR <30. The tool flags this range. However, specific guidelines vary by agent class (group I vs. II vs. III macrocyclic agents).

Should I use this for clinical decisions?

No. This is an educational reference only. Clinical decisions must follow institution protocols, current ACR/ESUR guidelines, and a qualified clinician's judgment. Patient-specific factors (diabetes, dehydration, nephrotoxic drugs) affect actual risk.

Why does sex affect the eGFR result?

Creatinine is produced mainly by muscle. Men typically have more muscle mass, so a given creatinine level implies a lower GFR in men than in women. The CKD-EPI equation uses different coefficients for each sex to account for this.

Can I enter creatinine in µmol/L?

Yes. Toggle the unit selector to µmol/L and the tool converts it internally (1 mg/dL = 88.42 µmol/L) before applying the CKD-EPI formula.

eGFR for Contrast Safety Checker

Name: eGFR for Contrast Safety Checker
Availability: InStock
Author: Nham Vu

Enter serum creatinine, age, and sex to get an estimated GFR and a contrast safety flag using the CKD-EPI 2021 equation.

Patient Parameters

Serum Creatinine

Age (years)

Biological Sex

Male Female

ACR Contrast Thresholds

≥ 45 — Generally safe for iodinated contrast

30–44 — Caution: hydration, benefit/risk review

< 30 — High risk: nephrology input advised

Educational reference only — not for clinical use.

Enter creatinine, age, and sex, then click Calculate.

Summary

Enter serum creatinine, age, and sex to get an estimated GFR and a contrast safety flag using the CKD-EPI 2021 equation.

How it works

Enter the patient's serum creatinine in mg/dL (or switch to µmol/L).
Select biological sex and enter age in years.
The CKD-EPI 2021 formula calculates eGFR in mL/min/1.73 m².
The result is compared to ACR/KDIGO contrast thresholds.
A color-coded risk label (Safe / Caution / High Risk) is displayed with guidance text.
Use the result to guide pre-scan preparation or nephrology consultation decisions.

Use cases

Pre-CT scan kidney function check before ordering iodinated contrast.
Pre-MRI gadolinium screening to rule out nephrogenic systemic fibrosis risk.
Quick bedside reference in radiology or emergency settings.
Resident and student education on contrast nephropathy risk stratification.
Verify whether oral or IV hydration pre-treatment is indicated.
Document GFR-based contrast safety rationale in patient records.

Frequently Asked Questions

Last updated: 2026-07-22 · Reviewed by Nham Vu