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)
MELD 3.0 = 4.56 × ln(bilirubin)
+ 0.82 × (137 − Na) − 0.24 × (137 − Na) × ln(bilirubin)
+ 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)
+ 6
MELD-Na (2016–2022)
First compute MELD:
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.
Clinical Application
A 47-year-old woman with cirrhosis from autoimmune hepatitis presents for transplant evaluation. Labs: creatinine 1.6 mg/dL, bilirubin 4.2 mg/dL, INR 1.8, sodium 129 mEq/L, albumin 2.8 g/dL. Not on dialysis.
- MELD ≈ 23 — uses creatinine 1.6, no sex adjustment
- MELD-Na ≈ 27 — hyponatremia (Na 129) adds urgency that MELD missed
- MELD 3.0 ≈ 32 — adds +1.33 for female sex; albumin 2.8 (below the 3.5 ceiling) adds further weight; sodium-creatinine interaction captured
- The nine-point difference between MELD and MELD 3.0 in this case illustrates why MELD systematically underestimated waitlist mortality in women — she would have been allocated as a MELD 23 under the old system
- At MELD 3.0 of 32, estimated 90-day waitlist mortality exceeds 45% — illustrating the prognostic magnitude that the original MELD of 23 failed to capture for this patient
- Enter her values into the calculator above to verify — note which constraints fire and how each variable contributes