The King's College Criteria calculator assists in determining the need for liver transplantation in cases of non-acetaminophen-induced acute liver failure. It uses five clinical parameters to compute a score that helps assess the severity of the patient's condition:

- **Age**: 
  - Less than 10 years: scores 1 point
  - 10 to 40 years: scores 0 points
  - Greater than 40 years: scores 1 point

- **Etiology regarding non-A/non-B hepatitis or idiosyncratic drug reactions**:
  - Yes: scores 1 point
  - No: scores 0 points

- **Duration of jaundice before encephalopathy onset**:
  - 7 days or less: scores 0 points
  - More than 7 days: scores 1 point
  
- **International normalized ratio (INR) for prothrombin time**:
  - Less than or equal to 3.5 (<= 50 seconds): scores 0 points
  - Between 3.5 and 6.5 (50 to 100 seconds): scores 1 point
  - Greater than 6.5 (> 100 seconds): scores 3 points

- **Serum bilirubin levels in micromoles per liter (mcmol/L)**:
  - Less than or equal to 300: scores 0 points
  - Greater than 300: scores 1 point

The score sums the values derived from these criteria, ranging from a minimum of 0 to a maximum of 7. Once computed, this score yields an interpretation:

- A score of 3 or more suggests the patient "Meets criteria for referral for liver transplantation". This indicates that the liver failure is severe and transplantation should be considered as a treatment option.
- A score less than 3 means "Criteria not met", implying that current conditions do not warrant immediate consideration for transplantation under this criteria set.

The King's College Criteria is a clinical scoring system specifically designed for patients with non-acetaminophen-induced acute liver failure. This calculator is used to predict the need for liver transplantation in patients with acute liver failure not caused by acetaminophen overdose. 

The King's College Criteria takes into account various clinical and laboratory parameters such as age, duration of jaundice before encephalopathy, prothrombin time, and serum bilirubin level. It helps clinicians to stratify the risk and make decisions about the urgency of liver transplantation.

Exclusion criteria for its use would be patients with acute liver failure due to acetaminophen overdose, as there is a separate King's College Criteria specifically for acetaminophen-induced acute liver failure. Additionally, it may not be applicable in patients with chronic liver disease or those with unclear etiology of liver failure.

King's College Criteria for non-acetaminophen-induced acute liver failure