MELD Score Calculator
The Model for End-Stage Liver Disease (MELD) score is a reliable measure of mortality risk in patients with end-stage liver disease. It is used by the United Network for Organ Sharing (UNOS) and Eurotransplant to prioritize patients for liver transplantation. The MELD-Na score incorporates serum sodium to further refine risk assessment.
Understanding the MELD Score
The MELD score is a numerical scale, ranging from 6 to 40, that indicates the severity of liver disease. A higher MELD score suggests more severe liver disease and a higher risk of death within three months. It was originally developed to predict survival in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) procedures but has since been adopted for liver transplant allocation.
Components of the MELD Score
The MELD score is calculated using a specific formula that incorporates several laboratory values:
- Serum Bilirubin: A measure of liver's ability to process bile. High levels indicate impaired liver function.
- INR (International Normalized Ratio): A measure of how quickly blood clots. A high INR indicates impaired liver synthesis of clotting factors.
- Serum Creatinine: A measure of kidney function. Liver disease can affect kidney function, and higher creatinine levels indicate poorer kidney health.
- Serum Sodium (for MELD-Na): Sodium levels are incorporated into the MELD-Na score, which is a refinement of the original MELD score. Low sodium levels (hyponatremia) in liver disease patients are associated with increased mortality.
- Dialysis Status: Patients who have received at least two dialysis treatments within the last 7 days are assigned a maximum creatinine value of 4.0 mg/dL, reflecting severe kidney impairment.
How the MELD Score is Calculated (Simplified)
The calculation involves a complex logarithmic formula. The basic MELD score (without sodium) is derived from bilirubin, INR, and creatinine. For patients with a MELD score above 11, a sodium adjustment is applied to create the MELD-Na score. This adjustment accounts for the impact of serum sodium levels on prognosis.
Key considerations in the calculation include:
- Minimum values are applied to bilirubin (0.3 mg/dL), INR (1.0), and creatinine (0.3 mg/dL) to prevent negative logarithms and ensure a baseline score.
- Creatinine is capped at 4.0 mg/dL. If a patient is on dialysis, their creatinine is automatically set to 4.0 mg/dL.
- For the sodium adjustment, serum sodium values are capped between 125 mEq/L and 137 mEq/L.
- The final MELD-Na score is capped at 40.
Interpreting Your MELD Score
The MELD score is a dynamic tool, and scores can change over time. It's important to remember that this calculator provides an estimate based on the provided inputs and should not replace professional medical advice. A higher score generally indicates a more urgent need for liver transplantation and a poorer prognosis without it.
- 6-9: Relatively low risk of mortality.
- 10-19: Moderate risk.
- 20-29: High risk.
- 30-40: Very high risk, indicating severe liver disease and urgent need for transplant evaluation.
Example Calculation
Let's use the example values provided in the calculator:
- Serum Bilirubin: 2.5 mg/dL
- INR: 1.8
- Serum Creatinine: 1.5 mg/dL
- Serum Sodium: 130 mEq/L
- Dialysis in last 7 days: No
Based on these inputs, the calculator would perform the following steps:
- All values are within their valid ranges and minimums/maximums.
- Calculate the MELD score without sodium adjustment:
MELD_no_Na = (3.78 * ln(2.5)) + (11.2 * ln(1.8)) + (9.57 * ln(1.5)) + 6.43MELD_no_Na ≈ (3.78 * 0.916) + (11.2 * 0.588) + (9.57 * 0.405) + 6.43MELD_no_Na ≈ 3.46 + 6.59 + 3.88 + 6.43 ≈ 20.36
Rounded to 20. - Since MELD_no_Na (20) is greater than 11, apply the sodium adjustment. Sodium (130) is within the 125-137 cap.
Sodium Adjustment = 1.32 * (137 - 130) - (0.033 * 20 * (137 - 130))Sodium Adjustment = 1.32 * 7 - (0.033 * 20 * 7)Sodium Adjustment = 9.24 - (0.033 * 140)Sodium Adjustment = 9.24 - 4.62 ≈ 4.62Final MELD-Na = 20 + 4.62 ≈ 24.62
Rounded to 25.
The calculated MELD-Na score for these inputs would be approximately 25.