Standard MELD Score Components
The standard MELD score is calculated using three laboratory parameters: total bilirubin, INR (International Normalized Ratio), and serum creatinine. 1, 2, 3, 1
Direct Answer to the Question
The correct answer is: Total bilirubin, INR, serum creatinine
The other options listed are incorrect:
- Platelet count is NOT part of the MELD calculation
- AST and ALT are NOT part of the MELD calculation
- Serum sodium is NOT part of the standard MELD score (though it is included in MELD-Na)
- Albumin is NOT part of the standard MELD score (though it is part of Child-Pugh and MELD 3.0)
The MELD Formula
The standard MELD score uses the following mathematical formula 2:
MELD = 3.8 × log(bilirubin in mg/dL) + 11.2 × log(INR) + 9.6 × log(creatinine in mg/dL) + 6.4
This creates a numerical scale ranging from 6 (less ill) to 40 (gravely ill) for individuals 12 years or older 1.
Clinical Context
The MELD score was originally developed to assess mortality risk in patients undergoing transjugular intrahepatic portosystemic shunts (TIPS), but has since been adopted by the United Network for Organ Sharing (UNOS) to stratify patients on the liver transplantation waiting list according to their risk of death within 3 months 1, 3. The score provides an objective assessment based on widely available laboratory tests and has proven superior to the Child-Turcotte-Pugh score for predicting 90-day mortality 4, 5.
Important Caveats
Laboratory methodology matters: Different thromboplastin reagents used to measure INR can yield significantly different MELD scores for the same patient 6, 7. Studies have shown that specific laboratory methodologies can produce MELD scores up to 20% higher, potentially affecting transplant priority 7.
Serum creatinine limitations: Creatinine can be an unreliable marker of renal dysfunction in patients with cirrhosis, which is why MELD 3.0 now caps creatinine at 3.0 mg/dL 1, 8.
The question specifically asks about the standard MELD score, not MELD-Na (which adds sodium) or MELD 3.0 (which adds sex and albumin) 8.