From the Guidelines
Fatty liver disease is diagnosed through a combination of clinical evaluation, laboratory tests, imaging studies, and sometimes liver biopsy, with the most recent guidelines emphasizing the importance of ruling out other causes of liver disease and confirming the absence of significant alcohol consumption 1. The diagnosis typically begins with abnormal liver function tests, particularly elevated liver enzymes (ALT and AST), and imaging techniques such as ultrasound, CT scan, or MRI can detect fat accumulation in the liver. Some key points to consider in the diagnosis of fatty liver disease include:
- Risk factors that strengthen the diagnosis, such as obesity, diabetes, metabolic syndrome, excessive alcohol consumption (for alcoholic fatty liver disease), and certain medications.
- The use of noninvasive tests, such as elastography or fibrosis biomarkers, to assess the risk of fibrosis.
- The potential need for referral to a liver specialist and liver biopsy for definitive diagnosis, particularly in cases where the diagnosis remains uncertain or to assess the severity of liver damage.
- The importance of distinguishing between simple fatty liver (steatosis) and more advanced forms with inflammation and fibrosis (steatohepatitis), with NASH being defined histologically as having ≥5% hepatic steatosis and associated with inflammation and hepatocyte injury (hepatocyte ballooning), with or without evidence of liver fibrosis 1. The most recent and highest quality study, published in 2024, provides the most up-to-date guidance on the diagnosis of fatty liver disease, and should be prioritized in clinical practice 1.
From the Research
Diagnosis of Fatty Liver Disease
The diagnosis of fatty liver disease can be achieved through various methods, including:
- Imaging studies, such as ultrasonography, computed tomography, magnetic resonance imaging with chemical shift imaging, and magnetic resonance spectroscopy and elastography 2
- Liver biopsy, which is considered the gold standard for diagnosis and staging of NAFLD, particularly for the diagnosis of NASH 3, 4, 2
- Clinical and image analysis-based approaches to quantify liver fat and evaluate fatty liver diseases from different medical imaging modalities 5
Criteria for Diagnosis
The criteria for diagnosing fatty liver disease include:
- Histological examination of liver tissue to detect steatosis, inflammation, liver cell injury, fibrosis, and architectural remodeling 4
- Imaging studies to detect fat accumulation in the liver and to assess the severity of the disease 2, 5
- Clinical evaluation to assess the presence of metabolic syndrome components, such as obesity and type 2 diabetes mellitus 6, 3
Staging of Fatty Liver Disease
The staging of fatty liver disease requires a liver biopsy to assess the degree of steatosis, inflammation, fibrosis, and architectural remodeling 4. The stages of fatty liver disease include: