MELD-Na Score Calculator

As portal hypertension advances, splanchnic arterial vasodilatation leads to a reduction in effective arterial blood volume. This triggers compensatory activation of the renin-angiotensin-aldosterone system (RAAS), the sympathetic nervous system, and — critically — non-osmotic release of antidiuretic hormone (ADH/vasopressin). The elevated ADH causes retention of free water in excess of sodium, producing dilutional hyponatraemia despite a total body sodium that is actually increased (manifesting as ascites and oedema).

The degree of hyponatraemia correlates with the severity of portal hypertension and haemodynamic derangement. Serum sodium below 130 mEq/L generally indicates advanced circulatory dysfunction and is associated with refractory ascites, hepatorenal syndrome, and hepatic encephalopathy. This explains why sodium independently predicts mortality beyond what bilirubin, INR, and creatinine capture.

Hyponatraemia in cirrhosis is associated with multiple adverse clinical outcomes beyond transplant waitlist mortality. Neurologically, chronic hyponatraemia impairs cognitive function and contributes to hepatic encephalopathy — the combination of hyperammonaemia and hypo-osmolality causes astrocyte swelling that exacerbates cerebral dysfunction. Patients with cirrhosis and sodium below 130 mEq/L have significantly higher rates of falls, confusion, and hospitalisation.

Perioperatively, severe hyponatraemia increases the risk of central pontine myelinolysis (osmotic demyelination syndrome, ODS) during liver transplantation. Rapid sodium correction occurs inevitably when the transplanted liver restores normal hepatic function and ADH suppression returns to normal. Transplant centres typically manage this by targeting a sodium correction rate of ≤ 8–10 mEq/L per 24 hours in the immediate post-operative period, often using hypotonic fluid infusions prophylactically.

Fluid restriction is the cornerstone of management for dilutional hyponatraemia in cirrhosis. A typical restriction of 1,000–1,500 mL/day can modestly improve serum sodium but is difficult for patients to maintain long-term. Its effectiveness is limited in severe cases where ADH levels are very high.

Vasopressin receptor antagonists (vaptans) — such as tolvaptan — block the V2 receptor in the collecting duct, promoting free water excretion without sodium loss. While effective at raising serum sodium, their use in cirrhosis is controversial: the FDA issued a warning against tolvaptan use for more than 30 days due to hepatotoxicity risk. Additionally, rapid correction of sodium must be avoided. Vaptans are not routinely used to “raise the MELD-Na” for allocation purposes — this would constitute inappropriate gaming of the system.

Albumin infusion may transiently improve effective arterial volume and reduce ADH secretion, modestly increasing sodium. However, the benefit is temporary. The definitive treatment for cirrhotic hyponatraemia is liver transplantation, which restores normal haemodynamics and ADH regulation.

While most hyponatraemia in cirrhosis is dilutional (hypervolaemic), clinicians must consider true hypovolaemic hyponatraemia — particularly in patients with excessive diuretic use, GI losses from diarrhoea or lactulose overuse, or large-volume paracentesis without albumin replacement. In these cases, sodium depletion is the primary mechanism rather than water retention.

The clinical distinction matters: hypovolaemic hyponatraemia in cirrhosis should be treated with volume repletion (isotonic saline or albumin) and reduction or cessation of diuretics, whereas dilutional hyponatraemia worsens with saline infusion. Key differentiating features include low urinary sodium (< 10 mEq/L) in hypovolaemic states, recent diuretic intensification, and clinical signs of volume depletion (orthostatic hypotension, tachycardia, dry mucous membranes without peripheral oedema).

Diuretics are the mainstay of ascites management in cirrhosis, but they have complex effects on serum sodium. Spironolactone (the preferred first-line agent) is a relatively potassium-sparing, sodium-wasting diuretic that can worsen hyponatraemia. Furosemide causes both sodium and water loss, with variable effects on serum sodium depending on the relative proportion of each lost.

Aggressive diuresis can lower serum sodium, which increases the MELD-Na score. This creates a clinical tension: effective ascites management may inadvertently raise the transplant allocation score. Conversely, withholding diuretics to “preserve” a higher sodium may worsen ascites control and quality of life. The correct approach is to manage ascites appropriately and allow the MELD-Na to reflect the patient’s true physiological state rather than optimising it artificially in either direction.

Because lower sodium raises the MELD-Na, there is a theoretical risk of manipulating serum sodium — for example, by over-diuresing, withholding fluid restriction, or using hypertonic saline sparingly — to artificially inflate the score. While deliberate gaming is considered rare, unintentional sodium-lowering effects of standard cirrhosis management (diuretics, fluid overload from IV albumin infusions) can genuinely alter the score.

OPTN monitors for anomalous patterns in sodium reporting and MELD-Na trends. Clinicians should manage sodium according to clinical needs and not adjust management strategies specifically to influence the transplant allocation score. Documentation of the clinical rationale for diuretic doses and fluid management is good practice in transplant-listed patients.

The MELD-Na formula bounds sodium between 125 and 137 mEq/L. A sodium of 118 mEq/L is treated identically to 125 mEq/L — no additional points are awarded. This “floor” means that patients with the most severe hyponatraemia (Na < 125) do not receive additional prioritisation beyond the 125 threshold, despite having substantially worse outcomes. Conversely, patients with sodium above 137 receive no sodium adjustment, and the MELD-Na equals the original MELD.

The floor at 125 was deliberately chosen because very severe hyponatraemia (< 125) is uncommon and often reflects acute complications (excessive diuresis, fluid overload) that may be transient. However, this design means the MELD-Na may still underestimate mortality in patients with persistent, severe hyponatraemia below 125.

The sodium adjustment is only applied when the original MELD score exceeds 11. At MELD(i) ≤ 11, the MELD-Na equals the original MELD regardless of sodium level. This design reflects the statistical finding that hyponatraemia does not significantly improve mortality prediction in patients with well-compensated liver disease.

However, this threshold creates a discontinuity: a patient with MELD(i) of 12 and Na of 125 receives the sodium adjustment, while a patient with MELD(i) of 11 and Na of 125 does not — despite both having severe hyponatraemia and potentially similar clinical profiles. Clinicians should be aware that patients with MELD(i) ≤ 11 and significant hyponatraemia may be more unwell than their MELD-Na suggests.

Accurate sodium measurement is essential because small changes (2–3 mEq/L) can shift the MELD-Na by 2–4 points in moderate-MELD patients. Sample haemolysis, prolonged transport times, and the use of indirect ion-selective electrode (ISE) analysers can all introduce error. Indirect ISE methods — used in many central laboratories — may produce falsely low sodium readings in patients with severe hyperbilirubinaemia or lipaemia, both common in end-stage liver disease.

Direct ISE methods (point-of-care blood gas analysers) are generally more accurate in this population. Clinicians should be aware of their laboratory’s method and should repeat borderline sodium measurements if the result seems inconsistent with the clinical picture. For transplant allocation, the sodium value used should be from the same laboratory draw as the other MELD components.

As with the original MELD, patients on warfarin have INR values that reflect the anticoagulant effect rather than hepatic synthetic dysfunction. This artificially inflates the MELD and MELD-Na scores. Common indications for warfarin in cirrhosis include portal vein thrombosis and atrial fibrillation — both of which are prevalent in this population.

There is no standard adjustment for warfarin use in the MELD-Na formula. Some transplant centres document the indication and degree of INR elevation attributable to anticoagulation. For patients being evaluated for listing, measuring INR after warfarin cessation (with appropriate bridging) can provide a more accurate baseline. Direct-acting oral anticoagulants (DOACs) have minimal impact on the INR and do not create this confound, though their use in cirrhosis remains controversial due to altered hepatic metabolism.