- In the CI-AKI Risk Calculator, choose Conventional (mg/dL) or SI (µmol/L) units, then enter the patient's eGFR (which scores 2–6 points by band), serum creatinine, and body weight — the latter two drive the maximum safe contrast-volume estimate.
- Select each clinical risk factor present — hypotension, IABP, congestive heart failure, age > 75, anemia, and diabetes. Results update live: the Mehran score, the corresponding CI-AKI risk band, and the maximum safe contrast volume.
- Use the second Mehran Score Calculator for a checkbox-style scoring that additionally folds in the planned contrast volume (1 point per 100 mL) and lets you enter renal function as either creatinine or eGFR. It reports the predicted CIN risk and dialysis risk for the total score.
- Compare the planned contrast volume against the calculated maximum safe volume, and use the risk band to decide on hydration, contrast minimization, and post-procedure creatinine monitoring.
All computation runs in your browser; no values are stored or transmitted.
When to Use
Use this tool before any procedure that uses iodinated contrast — coronary angiography or PCI, contrast-enhanced CT, or peripheral angiography — to quantify a patient's risk of contrast-associated (contrast-induced) acute kidney injury and to set a ceiling on the contrast dose. It pairs the Mehran risk score with a maximum safe contrast volume derived from body weight and serum creatinine.
Appropriate use
Adults scheduled for an iodinated-contrast procedure, especially those with CKD, diabetes, heart failure, anemia, advanced age, or hemodynamic instability. Best applied during pre-procedure planning to guide hydration, contrast minimization, medication holds, and the intensity of post-procedure creatinine monitoring.
When NOT to rely on it
The Mehran score was derived and validated in patients undergoing percutaneous coronary intervention; its absolute risk estimates may not transfer exactly to CT or non-coronary angiography. It does not by itself decide whether a needed, potentially life-saving contrast study should proceed — a high score signals the need for precautions, not automatic cancellation. The maximum-volume formula is a guide, not a hard limit, and assumes a stable baseline creatinine.
Pearls & Pitfalls
Hydration and dose minimization do the heavy lifting
The most evidence-based preventives are isotonic intravenous volume expansion in at-risk patients and keeping the contrast volume as low as possible — ideally at or below the calculated maximum safe dose. A high Mehran score should prompt these measures and a planned follow-up creatinine, not reflexive cancellation of a needed study.
Watch the contrast-volume–to–kidney-function ratio
Both the per-100 mL Mehran points and the Cigarroa dose ceiling reflect the same principle: risk rises with the contrast load relative to renal reserve. In high-risk patients, targeting a contrast-volume–to–eGFR ratio below roughly 3 is a practical operative goal.
Pitfalls
(1) The Mehran score was derived in PCI patients — applying its absolute risk percentages to contrast CT or non-coronary studies is an extrapolation. (2) N-acetylcysteine and isotonic sodium bicarbonate showed no benefit over saline in the large PRESERVE trial; do not substitute them for adequate hydration and dose limitation. (3) The maximum-volume formula assumes a stable baseline creatinine and is invalid in evolving AKI. (4) A "normal" creatinine can still mask substantially reduced GFR in elderly or low-muscle-mass patients — use eGFR.
Why Use It
Contrast-associated AKI prolongs hospital stay and is associated with higher short- and long-term mortality and, rarely, dialysis dependence. Risk is not uniform: a young patient with normal kidneys faces a very low risk, whereas an elderly diabetic with CKD, heart failure, and anemia can exceed a 50% risk after a large contrast load. Stratifying that risk up front lets the team weigh contrast against alternatives, ensure adequate peri-procedural hydration, minimize the dose toward the calculated safe ceiling, hold nephrotoxins, and schedule follow-up creatinine — the interventions that actually reduce harm.
CI-AKI Risk Calculator — Mehran Score & Maximum Safe Contrast Volume
Calculate the Mehran risk score for contrast-induced acute kidney injury before any procedure involving iodinated contrast dye (CT scan with contrast, coronary angiogram, angioplasty). Also calculates the maximum safe contrast volume for your kidney function.
⚕ Mehran score components: eGFR scoring (2–6pts based on GFR), hypotension (5pts), IABP (5pts), CHF (5pts), age >75 (4pts), anemia (3pts), DM (3pts), contrast volume (1pt per 100mL). CI-AKI risk: ≤5 = 7.5%; 6–10 = 14%; 11–16 = 26.1%; >16 = 57.3% (Mehran et al., JACC 2004). Max safe contrast volume = 5 mL × body weight (kg) ÷ serum creatinine (mg/dL). This tool supports procedural risk counseling — final decisions require cardiologist/radiologist assessment.
Mehran Score Calculator — Contrast-Induced Nephropathy Risk
Tick the risk factors that apply, enter the planned contrast volume, and choose either serum creatinine or eGFR. The Mehran score (Mehran et al., 2004) estimates the risk of contrast-induced nephropathy and dialysis after a coronary procedure or contrast study, and updates instantly as you type.
⚕ Mehran score (Mehran et al., J Am Coll Cardiol 2004;44:1393–9): hypotension 5, IABP 5, CHF 5, age >75 = 4, anemia 3, diabetes 3, contrast 1 pt/100 mL, and renal impairment (SCr >1.5 mg/dL = 4, or by eGFR 40–60 = 2 / 20–40 = 4 / <20 = 6). Risk bands: ≤5 ≈ 7.5% CIN (0.04% dialysis); 6–10 ≈ 14% (0.12%); 11–16 ≈ 26.1% (1.09%); ≥16 ≈ 57.3% (12.6%). The score was derived for percutaneous coronary intervention; it requires physician interpretation and is not a substitute for individualized cardiology/radiology assessment.
Next Steps
Use the result to support — not replace — clinical judgment.
- Interpret the value against the targets shown in the calculator and the Evidence section below, in the context of the full clinical picture.
- Trend serial measurements rather than acting on a single result; confirm abnormal or unexpected values before changing management.
- Apply the relevant KDIGO / specialty-guideline threshold and document the indication.
- Escalate or refer to nephrology when results are out of range, rapidly changing, or discordant with the clinical picture — and discuss the implications with the patient.
Evidence & References
Formula & Equations
Mehran risk score — point assignment
| Risk factor | Points |
|---|---|
| Hypotension (SBP <80 mmHg >1 h requiring pressors/IABP) | 5 |
| Intra-aortic balloon pump (IABP) | 5 |
| Congestive heart failure (NYHA III–IV or pulmonary edema) | 5 |
| Age > 75 years | 4 |
| Anemia (baseline Hct <39% men / <36% women) | 3 |
| Diabetes mellitus | 3 |
| Contrast volume | 1 per 100 mL |
| Renal impairment — serum creatinine > 1.5 mg/dL | 4 |
| Renal impairment — by eGFR: 40–60 / 20–40 / <20 mL/min/1.73 m² | 2 / 4 / 6 |
Risk bands (total score)
| Total score | CI-AKI risk | Dialysis risk |
|---|---|---|
| ≤ 5 (Low) | 7.5% | 0.04% |
| 6–10 (Moderate) | 14.0% | 0.12% |
| 11–16 (High) | 26.1% | 1.09% |
| ≥ 16 (Very high) | 57.3% | 12.6% |
Maximum safe contrast volume
| Quantity | Equation |
|---|---|
| Maximum acceptable contrast dose (mL) | 5 mL × body weight (kg) ÷ serum creatinine (mg/dL) |
The Mehran integer-weighting scheme and its four risk strata are taken directly from the 2004 derivation/validation cohort. The maximum-contrast-dose rule (Cigarroa formula) caps the iodinated load relative to body size and renal function; many operators further target a contrast-volume–to–eGFR ratio (CV/eGFR) below ~3 in high-risk cases.
Evidence & References
The risk score and its strata are from Mehran and colleagues' 2004 development and validation of a simple integer-weighted model in 8,357 patients undergoing percutaneous coronary intervention. The body-weight/creatinine contrast-dose ceiling is the Cigarroa formula. Preventive measures (volume expansion, contrast minimization) are summarized in the KDIGO AKI guideline and subsequent trials such as PRESERVE.
- Mehran R, Aymong ED, Nikolsky E, et al. A simple risk score for prediction of contrast-induced nephropathy after percutaneous coronary intervention: development and initial validation. J Am Coll Cardiol. 2004;44(7):1393–1399.
- Cigarroa RG, Lange RA, Williams RH, Hillis LD. Dosing of contrast material to prevent contrast nephropathy in patients with renal disease. Am J Med. 1989;86(6 Pt 1):649–652.
- Kidney Disease: Improving Global Outcomes (KDIGO) Acute Kidney Injury Work Group. KDIGO Clinical Practice Guideline for Acute Kidney Injury. Kidney Int Suppl. 2012;2(1):1–138.
- Weisbord SD, Gallagher M, Jneid H, et al. Outcomes after angiography with sodium bicarbonate and acetylcysteine (PRESERVE Trial). N Engl J Med. 2018;378(7):603–614.
- Nyman U, Almén T, Aspelin P, et al. Contrast-medium dose-to-GFR ratio: a measure of systemic exposure to predict contrast-induced nephropathy. Acta Radiol. 2008;49(6):658–667.
