MELD-Na (MELD with Sodium) was developed to address the limitations of the standard MELD score, which underestimates waitlist mortality in cirrhotic patients with hyponatraemia. Hyponatraemia (serum sodium <135 mEq/L) is independently associated with a 2-3× increased risk of 90-day waitlist mortality in cirrhosis. Biggins and colleagues (2006) demonstrated that incorporating serum sodium significantly improved the prognostic accuracy of MELD. UNOS officially adopted MELD-Na for organ allocation in January 2016, replacing standard MELD as the primary allocation score. Serum sodium is capped at 125-137 mEq/L to prevent gaming by aggressive sodium correction.