Background
The MELD score was not originally designed for transplant allocation. In 2000, Malinchoc et al. at Mayo Clinic developed it to predict 3-month survival after transjugular intrahepatic portosystemic shunt (TIPS) procedures — identifying patients too sick to tolerate the hemodynamic stress of portal decompression.1 Using Cox regression in a cohort of 231 patients, the model combined three objective laboratory values (creatinine, bilirubin, INR) and etiology of liver disease, outperforming Child-Pugh at that specific indication.
Kamath et al. then validated MELD's broader prognostic value across diverse causes of end-stage liver disease and proposed it as a general measure of short-term mortality in cirrhosis.2 Recognizing its objectivity and reproducibility — free of the subjective variables embedded in Child-Pugh scoring (ascites grading, encephalopathy stage) — UNOS adopted MELD for national organ allocation in 2002. The shift replaced a system in which waiting time drove priority, directing organs to the sickest candidates first.
How MELD Evolved
Each version added variables to address a documented source of allocation inequity or prognostic blind spot. Understanding why each change was made is as important as knowing the formula.
Developed by Malinchoc et al. at Mayo Clinic to predict 3-month survival after TIPS — not originally designed for transplant allocation. Adopted by UNOS in 2002, replacing the Child-Pugh score and waiting-time system. The sickest first principle replaced time on the waitlist as the allocation criterion.
Multiple prospective studies demonstrated that hyponatremia (Na <135 mEq/L) independently predicted waitlist mortality beyond what MELD captured — reflecting the severity of splanchnic vasodilation and neurohormonal activation in advanced portal hypertension. UNOS adopted MELD-Na in January 2016. Patients with clinically significant hyponatremia appropriately moved up the waitlist.
Kim WR et al. (Hepatology 2021) reanalyzed national registry data with the explicit goal of eliminating sex-based mortality disparities. Key changes: (1) +1.33 points for female sex — directly corrects for documented mortality gap at equivalent scores; (2) albumin added — captures malnutrition and hepatic synthetic failure not fully reflected by bilirubin or INR; (3) creatinine ceiling lowered to 3.0 mg/dL (from 4.0) to reduce the outsized influence of extreme creatinine values; (4) regression coefficients updated using contemporary cohort data.
MELD Calculator
Calculates MELD, MELD-Na, and MELD 3.0 simultaneously. Constraints (floors, ceilings, dialysis rules) are applied automatically per OPTN/SRTR policy — the same logic used in official allocation. For clinical or allocation decisions, use the official SRTR calculator.
For official organ allocation decisions, use the SRTR MELD calculator at srtr.org. MELD 3.0 is rounded to the nearest whole number for allocation purposes.
Score Explorer
Drag the slider to explore how 90-day waitlist mortality changes across the MELD 3.0 range. Note the inflection around MELD 15 — the established threshold where survival benefit from transplantation outweighs operative risk. When you compute a score above using the calculator, the slider updates automatically.
Formulas and Variable Constraints
Every MELD formula applies floors and ceilings to prevent extreme values from dominating the score. These constraints are enforced automatically by OPTN/SRTR — they are not optional.
MELD 3.0 (Current Allocation Score)
+ 0.82 × (137 − Na) − 0.24 × (137 − Na) × ln(creatinine)
+ 9.09 × ln(INR)
+ 11.14 × ln(creatinine)
+ 1.85 × (3.5 − albumin) − 1.83 × (3.5 − albumin) × ln(creatinine)
+ 1.33 × (female sex: 1 if female, 0 if male)
+ 7
MELD-Na (2016–2022)
MELD = 3.78 × ln(bilirubin) + 11.2 × ln(INR) + 9.57 × ln(creatinine) + 6.43
Then: MELD-Na = MELD + 1.32 × (137 − Na) − 0.033 × MELD × (137 − Na)
Variable Constraints by Formula
| Variable | MELD (original) | MELD-Na | MELD 3.0 |
|---|---|---|---|
| Creatinine | Min 1.0, max 4.0 Dialysis → 4.0 |
Min 1.0, max 4.0 Dialysis → 4.0 |
Min 1.0, max 3.0 Dialysis → 3.0 |
| Bilirubin | Min 1.0 | Min 1.0 | Min 1.0 |
| INR | Min 1.0 | Min 1.0 | Min 1.0 |
| Sodium | — (not used) | Min 125, max 137 | Min 125, max 137 |
| Albumin | — (not used) | — (not used) | Min 1.5, max 3.5 |
| Final score | Min 6, max 40 | Min 6, max 40 | Min 6, max 40 |
Dialysis rule: If the candidate has received hemodialysis (HD) or continuous venovenous hemodialysis (CVVHD) at least twice in the prior 7 days, creatinine is automatically set to the maximum value — 4.0 mg/dL for MELD/MELD-Na, 3.0 mg/dL for MELD 3.0. This prevents underestimation of renal failure severity in dialysis-dependent patients whose measured creatinine may be artificially low from prior sessions.
Trajectory matters more than a single value. A MELD 3.0 rising from 14 to 22 over three months signals accelerating hepatic decompensation and warrants more urgent action than a stable MELD 3.0 of 22. Monitor trends at each visit.
Status 1A and 1B: Patients with acute liver failure (ALF) or certain acute-on-chronic presentations are designated Status 1A — they bypass MELD-based allocation entirely due to the immediacy of death without transplantation (days, not months). Pediatric acute liver failure follows Status 1B criteria. MELD does not apply to these designations.
Exception points: Some conditions (hepatocellular carcinoma within Milan criteria, hepatopulmonary syndrome, portopulmonary hypertension, and others) qualify for MELD exception points — additional MELD 3.0 points assigned by a regional review board to account for mortality risk not captured by lab values. Understanding exception points is important when managing transplant candidates.