MELD Calculator – Model for End-Stage Liver Disease

The Model for End-Stage Liver Disease (MELD) is a validated, objective scoring system used to quantify the severity of chronic liver disease and to predict short-term mortality in patients with cirrhosis. Originally developed at the Mayo Clinic to assess 3-month survival after transjugular intrahepatic portosystemic shunt (TIPS) procedures, it was subsequently adopted by the United Network for Organ Sharing (UNOS) in 2002 as the primary tool for prioritising liver transplant allocation in the United States and has since been adopted widely around the world. The MELD formula uses three routine serum laboratory values: creatinine (a marker of kidney function, which is closely coupled to liver failure through the hepatorenal syndrome), bilirubin (a direct indicator of hepatic synthetic and excretory function), and the International Normalized Ratio (INR, which reflects the liver's capacity to produce coagulation factors). Each variable is log-transformed because the relationship between these biomarkers and mortality is exponential rather than linear. A constant of 6.43 is added to centre the score distribution. All three values are floored at 1.0 to prevent the logarithm of values less than 1 from producing a negative contribution to the score, which would be clinically misleading. In patients receiving haemodialysis or peritoneal dialysis at least twice per week, creatinine is fixed at 2.0 mg/dL regardless of the measured value. This correction acknowledges that dialysis artificially lowers serum creatinine and would otherwise underestimate kidney dysfunction — and therefore overall disease severity — in dialysis-dependent patients. Creatinine is also capped at 4.0 mg/dL to prevent the score from being driven to extreme values by acute kidney injury alone. The MELD-Na score (also called MELD 3.0 sodium adjustment) extends the original formula by incorporating serum sodium, which is an independent predictor of waitlist mortality in patients with cirrhosis. Hyponatraemia is a marker of advanced portal hypertension and neurohumoral activation, and its inclusion improves the discriminative ability of the score. Sodium is clamped between 125 and 137 mEq/L; values outside this range are set to the nearest boundary before the adjustment formula is applied. MELD scores are interpreted on a continuum: scores below 10 indicate relatively stable disease; 10–19 moderate risk; 20–29 serious risk with approximately one in five patients dying within 3 months; 30–39 severe risk; and 40 or above critical risk with greater than 70% 3-month mortality. Liver transplant centres use these thresholds alongside other clinical factors to assess urgency and allocate organs equitably. The calculator is provided for educational purposes and clinical decision support; it does not replace formal transplant evaluation or specialist medical advice.