Steatotic Liver Disease (SLD) Classification
A visual guide to the modern definitions of liver disease
MASLD
Metabolic Dysfunction-Associated Steatotic Liver Disease
Requires at least 1 cardiometabolic risk factor.
MetALD
Overlap: Metabolic Dysfunction + Alcohol
Female: 140–350g | Male: 210–420g
Combined driver of liver injury
ALD
Alcohol-Associated Liver Disease
Driven primarily by high alcohol consumption.
Specific Aetiology
Cryptogenic
Steatosis with no identified cause or risk factors.
Detailed Breakdown of Conditions
1. MASLD (Metabolic Dysfunction-Associated Steatotic Liver Disease)
The Condition
Formerly known as NAFLD, this is the most common form of liver disease. It is defined by the buildup of excess fat in the liver (steatosis) combined with at least one "cardiometabolic" risk factor, such as obesity, type 2 diabetes, or high blood pressure. It is not caused by alcohol.
Diagnosis
Doctors typically use blood tests (to check liver enzymes and calculate fibrosis scores like FIB-4) and imaging (Ultrasound or FibroScan) to detect fat and stiffness. A key requirement is ruling out other causes like viral hepatitis or heavy alcohol use.
Treatment
The primary treatment is lifestyle modification aimed at weight loss (7-10% body weight) through diet and exercise. Doctors also focus on aggressively treating the associated metabolic issues—using medications for diabetes (like GLP-1 agonists) and cholesterol to protect the liver and heart.
2. MetALD (Metabolic and Alcohol Associated)
The Condition
This is a newly defined "overlap" category. It describes patients who have the metabolic risk factors of MASLD (like diabetes or obesity) but also consume moderate amounts of alcohol. In this group, both the metabolic issues and the alcohol contribute to liver damage.
Diagnosis
Diagnosis relies on a detailed patient history to quantify alcohol intake. It applies to females consuming 140–350g of alcohol per week and males consuming 210–420g per week. Standard liver imaging and blood tests are used to assess the severity of the injury.
Treatment
Treatment requires a dual approach. Patients are advised to reduce or cease alcohol consumption entirely, as even moderate amounts are harmful in the presence of metabolic dysfunction. Simultaneously, metabolic risk factors (weight, sugar, lipids) must be managed medically.
3. ALD (Alcohol-Associated Liver Disease)
The Condition
ALD is liver damage caused primarily by excess alcohol consumption (typically defined as >350g/week for women or >420g/week for men). It ranges from reversible fatty liver to severe alcoholic hepatitis and permanent cirrhosis.
Diagnosis
Diagnosis is based on a history of heavy alcohol use and physical signs of chronic liver disease (such as jaundice). Lab tests often show a specific pattern where the AST enzyme is significantly higher than the ALT enzyme.
Treatment
The cornerstone of treatment is complete abstinence from alcohol, often supported by addiction specialists. Nutritional support is vital as malnutrition is common. In severe cases of acute inflammation (hepatitis), corticosteroids may be used, with liver transplantation as a final option for end-stage failure.
4. Specific Aetiology & Cryptogenic SLD
Specific Aetiology SLD
Condition: Liver fat caused by distinct, known triggers unrelated to common metabolic factors.
Causes: Includes side effects from certain medications (Drug-Induced Liver Injury), genetic disorders (like Wilson disease), or malnutrition.
Cryptogenic SLD
Condition: A "diagnosis of exclusion." This label is used when a patient has fatty liver disease, but doctors cannot find any metabolic risk factors (like obesity or diabetes) and have ruled out alcohol and genetic causes.
Management
Specific: Treatment targets the root cause (e.g., stopping the offending drug or treating the genetic condition).
Cryptogenic: Often managed similarly to MASLD, with close monitoring to see if metabolic risk factors develop over time.
Reference: 2023 Multi-society Delphi consensus statement on new fatty liver disease nomenclature.