From the Guidelines
Steatosis, also known as fatty liver disease, is diagnosed through a combination of medical history, physical examination, blood tests, and imaging studies, with the most recent guidelines recommending a stepwise approach using blood-based scores and imaging techniques to rule-out/in advanced fibrosis 1. The diagnostic criteria for steatosis involve the presence of one or more cardiometabolic risk factors and the absence of harmful alcohol intake, with the spectrum of the disease including steatosis, metabolic dysfunction-associated steatohepatitis (MASH), fibrosis, cirrhosis, and MASH-related hepatocellular carcinoma (HCC) 1. Some key points to consider in the diagnosis of steatosis include:
- The presence of steatosis in >5% of hepatocytes according to histological analysis or a proton density fat fraction >5.6% assessed by proton magnetic resonance spectroscopy (1 H-MRS) or quantitative fat/water selective magnetic resonance imaging (MRI) 1
- The exclusion of secondary causes and daily alcohol consumption above certain limits, which indicates alcoholic liver disease 1
- The use of ultrasound as a first-line investigation tool for mild increase in liver enzymes, with a sensitivity of 84.8% and a specificity of 93.6% for moderate and severe hepatic fat deposition 1
- The importance of assessing for metabolic risk factors, such as obesity, glucose intolerance, and dyslipidemia, in patients with unsuspected hepatic steatosis detected on imaging 1 The most recent and highest quality study recommends a stepwise approach using blood-based scores, such as the fibrosis-4 index (FIB-4), and imaging techniques, such as transient elastography, to rule-out/in advanced fibrosis, which is predictive of liver-related outcomes 1.
From the Research
Diagnostic Criteria for Steatosis (Fatty Liver Disease)
The diagnostic criteria for steatosis, also known as fatty liver disease, involve a combination of clinical, laboratory, and imaging findings. The key criteria include:
- Hepatic steatosis, defined as 5% or greater accumulation of fat in liver cells (hepatocytes) 2, 3, 4
- Exclusion of other causes of liver disease, such as excessive alcohol use, viral hepatitis, and hepatotoxic medications 2, 3, 5
- Presence of risk factors, such as obesity, metabolic syndrome, and type 2 diabetes mellitus 2, 3, 5
Laboratory and Imaging Tests
Laboratory tests, such as liver function tests, and imaging studies, such as ultrasonography, computed tomography, and magnetic resonance imaging, can help diagnose and assess the severity of fatty liver disease 2, 6, 3, 5. These tests can:
- Detect hepatic steatosis and measure the degree of fat accumulation in the liver
- Evaluate liver function and detect any signs of liver damage or inflammation
- Exclude other causes of liver disease
Liver Biopsy
Liver biopsy is considered the gold standard for diagnosing nonalcoholic steatohepatitis (NASH), a more severe form of fatty liver disease characterized by inflammation and liver cell damage 2, 3, 5, 4. A liver biopsy can:
- Confirm the presence of NASH and assess the severity of liver damage
- Evaluate the degree of fibrosis and cirrhosis
- Help guide treatment decisions and monitor disease progression
Non-Invasive Tests
Non-invasive tests, such as elastography and biomarker tests, are being developed to diagnose and monitor fatty liver disease 6, 5. These tests can:
- Assess liver stiffness and detect fibrosis
- Evaluate the presence and severity of steatosis
- Help identify patients at high risk of disease progression and complications