Mehran Score Calculator (Contrast-Induced Nephropathy)

How to Use This Calculator

1. Select Yes/No for the 6 binary risk factors (hypotension, IABP, CHF, age > 75, anemia, diabetes).
2. Enter planned contrast volume in mL (1 point per 100 mL).
3. Enter serum creatinine and eGFR for renal scoring.
4. CIN risk tier and dialysis risk calculate automatically.
5. Use the Prevention tab for hydration protocol and safe contrast volume guidance.

Formula

Example

Frequently Asked Questions

• What is the Mehran score and what does it predict? ▼
  The Mehran score, also known as the Mehran contrast-induced nephropathy (CIN) risk score, is a validated clinical tool developed to predict the risk of acute kidney injury following the use of iodinated contrast media in patients undergoing percutaneous coronary intervention (PCI). It was developed by Mehran et al. at Columbia University and published in the Journal of the American College of Cardiology in 2004, derived from a retrospective analysis of 8,357 patients who underwent PCI. The score uses eight independent predictors: hypotension at the time of procedure (systolic BP below 80 mmHg for one hour or more requiring vasopressors or intra-aortic balloon pump), intra-aortic balloon pump (IABP) use, congestive heart failure NYHA class III or IV or history of pulmonary edema, age greater than 75 years, anemia (hematocrit below 39% in males or below 36% in females), diabetes mellitus, contrast volume (1 point per 100 mL), and renal function (serum creatinine greater than 1.5 mg/dL or eGFR-based points). CIN is defined as a rise in serum creatinine of 0.5 mg/dL or more, or a 25% or greater increase from baseline within 48 hours after contrast exposure. Four risk tiers are defined based on total score.
• What are the four Mehran risk tiers and their CIN rates? ▼
  The Mehran score stratifies patients undergoing PCI into four risk tiers for contrast-induced nephropathy. Low risk corresponds to a score of 5 or less, with a CIN rate of approximately 7.5% and a dialysis risk of only 0.04%. These patients can generally undergo standard PCI with routine precautions such as adequate hydration and minimum necessary contrast volumes. Moderate risk corresponds to a score of 6 to 10, with a CIN rate of approximately 14% and a dialysis risk of 0.12%. Targeted prevention strategies including IV hydration are recommended. High risk corresponds to a score of 11 to 16, with a CIN rate of 26.1% and a dialysis risk of 1.09%. These patients require intensive prevention protocols including IV isotonic saline before and after the procedure, minimum contrast volume, consideration of iso-osmolar or low-osmolar contrast, staging of complex procedures to reduce total contrast load, and 24-48 hour post-procedure creatinine monitoring. Very high risk corresponds to a score greater than 16, with a CIN rate of 57.3% and a dialysis risk of 12.6%. In this tier, every strategy to minimize renal injury must be employed, and the risk-benefit ratio of the planned procedure must be carefully discussed with the patient.
• How is contrast volume accounted for in the Mehran score and what is a safe limit? ▼
  In the Mehran score, contrast volume contributes 1 point per 100 mL of contrast used during the PCI procedure. This linear relationship reflects the well-established dose-response relationship between contrast volume and CIN risk — larger volumes increase both the osmotic load and direct tubular toxicity. However, the Mehran score should ideally be calculated before the procedure using planned or estimated contrast volumes, and the procedural plan should then be adjusted to minimize the total contrast dose once the CIN risk tier is known. Beyond the Mehran score itself, a widely used practical formula for the maximum safe contrast volume is 3.7 times the estimated glomerular filtration rate (eGFR) in mL/min/1.73m². For example, a patient with eGFR of 40 mL/min/1.73m² should receive no more than approximately 148 mL of contrast. This threshold should be respected rigorously in high and very high-risk patients. In complex multi-vessel PCI where the planned contrast volume exceeds the safe limit, staged procedures separated by 5 to 7 days allow adequate renal recovery between contrast exposures and dramatically reduce the cumulative CIN risk compared to performing everything in a single session.
• What IV hydration and prevention strategies reduce CIN risk? ▼
  Intravenous hydration is the best-supported intervention for reducing contrast-induced nephropathy risk and forms the cornerstone of prevention in high-risk patients. The standard protocol is isotonic (0.9%) sodium chloride infused at 1 mL/kg/hour beginning 3 to 12 hours before the procedure and continuing for 12 hours post-procedure. For emergency or urgent PCI where pre-procedure time is limited, accelerated protocols using 3 mL/kg/hour for 1 hour before the procedure are used. Isotonic sodium bicarbonate (154 mEq/L at 3 mL/kg/hour for 1 hour before and 1 mL/kg/hour for 6 hours after) is an alternative, though the evidence advantage over normal saline is modest and inconsistent across trials. N-acetylcysteine (1200 mg twice daily orally starting the day before and continuing the day of the procedure) has been widely used, though the PRESERVE trial and others showed no significant benefit over adequate hydration — its low cost and favorable safety profile make it acceptable but not definitively beneficial. Other key strategies include: using the minimum necessary contrast volume; employing low-osmolar or iso-osmolar contrast agents; avoiding nephrotoxic drugs (NSAIDs, aminoglycosides, ACE inhibitors in unstable patients) for 24-48 hours around the procedure; holding metformin; and monitoring creatinine at 24 and 48 hours post-procedure in high-risk patients.
• How does contrast-induced nephropathy affect long-term outcomes after PCI? ▼
  Contrast-induced nephropathy following PCI is not merely a transient laboratory abnormality — it is associated with serious short- and long-term adverse outcomes. In-hospital consequences of CIN include extended hospitalization, requirement for dialysis (in patients with very high Mehran scores), increased bleeding risk related to anticoagulant accumulation in the setting of impaired renal clearance, and increased in-hospital mortality. Long-term consequences are substantial: multiple observational studies and registry analyses have shown that patients who develop CIN after PCI have significantly higher rates of one-year and five-year mortality compared to those who do not, even after adjusting for baseline renal function. The mechanism involves both the direct renal injury leading to chronic kidney disease progression and the systemic inflammation, endothelial dysfunction, and neurohormonal activation triggered by acute kidney injury. Patients who require dialysis after PCI have in-hospital mortality rates of 36% or higher. The prognostic impact of CIN reinforces the importance of pre-procedure risk stratification using the Mehran score and rigorous implementation of prevention protocols in high-risk patients, where the goal is not merely to protect the kidneys acutely but to preserve long-term cardiovascular and renal outcomes.

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