From the Guidelines
The diagnosis of Non-Alcoholic Fatty Liver Disease (NAFLD) is based on a combination of clinical, laboratory, and imaging findings, with the presence of hepatic steatosis, absence of significant alcohol consumption, and absence of other causes of liver disease being key criteria [ 1 ].
Diagnostic Criteria for NAFLD
To diagnose NAFLD, the following criteria must be met:
- Presence of hepatic steatosis, typically identified by imaging studies such as ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI), showing fatty infiltration of the liver [ 1 ].
- Absence of significant alcohol consumption, defined as less than 21 standard drinks per week for men and less than 14 standard drinks per week for women [ 1 ].
- Absence of other causes of liver disease, such as viral hepatitis, autoimmune hepatitis, or genetic disorders [ 1 ].
- Elevated liver enzymes, such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), although normal liver enzymes do not rule out NAFLD [ 1 ].
- Optional: Liver biopsy, which is the gold standard for diagnosing NAFLD, showing steatosis affecting at least 5% of hepatocytes [ 1 ]. It is essential to note that the diagnosis of NAFLD should be made by a healthcare professional, and a comprehensive evaluation, including medical history, physical examination, laboratory tests, and imaging studies, is necessary to confirm the diagnosis [ 1 ].
Key Considerations
- Metabolic dysfunction–associated steatotic liver disease (MASLD) has been proposed to replace the term nonalcoholic fatty liver disease (NAFLD) to identify steatotic liver disease in the presence of at least one cardiometabolic risk factor associated with insulin resistance [ 1 ].
- A separate category outside of MASLD, named metabolic dysfunction and alcoholic liver disease (MetALD), was created for circumstances in which alcohol intake is greater than that allowed for NAFLD but less than that attributed to alcoholic liver disease [ 1 ].
From the Research
Diagnostic Criteria for Non-Alcoholic Fatty Liver Disease (NAFLD)
The diagnostic criteria for NAFLD include:
- A history of no or limited daily alcohol intake (<20 g for women and <30 g for men) 2
- Presence of hepatic steatosis by imaging or by histology 2
- Exclusion of other liver diseases 2
Stages of NAFLD
NAFLD progresses through the stages of:
- Simple steatosis 3, 4, 5, 6
- Nonalcoholic steatohepatitis (NASH) 3, 4, 5, 6
- Fibrosis 3, 4, 5, 6
- Cirrhosis 3, 4, 5, 6
- Hepatocellular carcinoma (HCC) 3, 4, 5, 6
Diagnostic Methods
The diagnosis of NAFLD can be achieved by:
- Imaging studies, such as ultrasonographic examination of the liver 4, 5, 6
- Liver biopsy, which is considered the gold standard for diagnosing NAFLD 3, 4, 5, 6, 2
- Non-invasive biomarkers, including serum markers or imaging modalities 6
- Magnetic Resonance technology, which can accurately quantify steatosis or identify fibrosis stage 6
Challenges in Diagnosis
Remaining challenges in the diagnosis of NAFLD include:
- The lack of a clear threshold alcohol intake for defining "non-alcoholic" 2
- A lacking consensus for the classification of fatty liver disease 2
- Absence of a histological definition of NASH, which currently remains the gold standard for the diagnosis 2
- The overlap of the criteria for NAFLD and alcoholic liver disease 2