What parameters are needed to calculate the Model for End-Stage Liver Disease (MELD) score for an adult patient with advanced liver disease?

MELD Score Parameters

The MELD score requires exactly three laboratory parameters: serum bilirubin (mg/dL), serum creatinine (mg/dL), and INR (International Normalized Ratio). 1, 2, 3

The Three Required Laboratory Values

• Serum bilirubin reflects hepatic excretory function and is measured in mg/dL 1, 3
• Serum creatinine assesses renal function, which is a critical prognostic marker in liver disease, and is measured in mg/dL 1, 2, 3
• INR (International Normalized Ratio) measures coagulation function and clotting factor synthesis 1, 3

How These Parameters Are Used

The MELD formula applies logarithmic transformations to these three values to generate a continuous score from 6 to 40, with higher scores indicating more severe disease and higher 3-month mortality risk. 4, 1, 3

Specifically, the mathematical formula incorporates:

• 3.8 × log(bilirubin in mg/dL) 2
• 11.2 × log(INR) 2
• 9.6 × log(creatinine in mg/dL) 2, 3

What MELD Does NOT Include

MELD deliberately excludes all subjective clinical parameters that are present in the Child-Pugh score, such as ascites, hepatic encephalopathy, nutritional status, or albumin. 4, 1, 3 This makes MELD entirely objective and reproducible across different centers. 1, 3

Important Clinical Considerations

• Laboratory methodology matters: Different laboratory methods can yield significantly different INR values, potentially changing MELD scores by up to 20% and affecting transplant priority. 5 The INR was originally calibrated for warfarin monitoring, not liver disease assessment. 6

• Interfering factors must be recognized: INR can be elevated by oral anticoagulants (not liver disease), and creatinine can be elevated by renal insufficiency independent of hepatorenal syndrome or lowered by sarcopenia. 4, 1, 7 When using MELD as a screening tool, 91% of patients required parameter adjustment for these interfering factors. 7

• Minimum creatinine value: For patients on dialysis or with very low creatinine, a floor value of 1.0 mg/dL is typically used in the calculation. 8

Enhanced MELD Variations

While the original MELD uses only these three parameters, MELD-Na adds serum sodium to improve mortality prediction, particularly in patients with low MELD scores and hyponatremia. 1, 9 Hyponatremia (sodium <130 mmol/L) is an independent predictor of death in cirrhotic patients with ascites. 1, 9

MELD 3.0, the most recent iteration, additionally incorporates patient sex and albumin levels to reduce gender disparities, though it is not yet widely implemented. 1