The MELD-Na calculator is utilized to evaluate the severity of liver disease and estimate mortality risk by using key laboratory values and clinical factors. It outputs a MELD-Na Score which is associated with a specific mortality risk percentage. Here's how the process works:

Input Data:
- Serum creatinine level, which can be in mg/dL (0 to 20) or converted from µmol/L (0 to 1768).
- Total bilirubin level, reported in mg/dL (0 to 50) or converted from µmol/L (0 to 855).
- International Normalized Ratio (INR), ranging from 0 to 10.
- Serum sodium level in either mEq/L or mmol/L, ranging from 100 to 180.
- Dialysis status in the past 7 days, which is a simple "Yes" or "No".

Computation Steps:
- First, if creatinine and bilirubin are provided in µmol/L, conversion to mg/dL is performed by dividing the creatinine value by 88.4 and bilirubin by 17.1.
- Then, initial adjustments are made where the minimum acceptable values for creatinine, bilirubin, and INR are set to 1.0. For creatinine, if the patient has undergone dialysis or the creatinine level exceeds 4.0 mg/dL, the value is restricted to a maximum of 4.0 mg/dL.
- Serum sodium levels are modified to ensure they fall within the 125 to 137 mEq/L range.
- The initial MELD score, termed MELD(i), is calculated using the formula:
  0.957 * ln(creatinine) + 0.378 * ln(bilirubin) + 1.120 * ln(INR) + 0.643
  This score is then multiplied by 10 and rounded.
- If the MELD(i) score exceeds 11, a sodium adjustment is applied to obtain the MELD-Na score:
  MELD-Na = MELD(i) + 1.32 * (137 - sodium) - (0.033 * MELD(i) * (137 - sodium))
- The resulting MELD-Na score is capped at a maximum value of 40 to prevent excessively high values.

Interpreting the Results:
- A MELD-Na score of 9 or less indicates a low mortality risk of 1.9%.
- Scores between 10 and 19 suggest a moderate risk with a mortality rate of 6.0%.
- For scores between 20 and 29, the mortality risk increases to 19.6%.
- A score in the range of 30 to 39 corresponds to a substantial risk of 52.6%.
- Finally, a MELD-Na score of 40 or greater reflects the highest mortality risk at 71.3%.

By following these steps, the calculator systematically provides an objective assessment of liver disease severity and correlates it with associated mortality risks, aiding clinicians in clinical decision-making.

The MELD-Na (UNOS/OPTN) score is used to estimate the severity of chronic liver disease and prioritize liver transplant candidates. It incorporates sodium levels, creatinine, bilirubin, and INR to assess short-term mortality risk. The formula includes adjustments for patients on dialysis and limits the score between 6 and 40

Model for End-Stage Liver Disease-Sodium (MELD-Na)