What are the signs of hepatic steatosis?

Signs of Hepatic Steatosis

Hepatic steatosis is most commonly asymptomatic (60-80% of cases), and when present, clinical signs are typically nonspecific and include hepatomegaly, right upper quadrant discomfort, and fatigue. 1, 2

Clinical Presentation

Symptoms (Often Absent)

• Most patients (60-80%) are completely asymptomatic, which is why steatosis is frequently discovered incidentally on imaging or through abnormal liver enzymes 1, 2
• When symptoms occur, they are nonspecific and may include:
  • Fatigue 1, 2
  • Right upper quadrant discomfort or epigastric fullness 1
  • Nausea 2
  • Muscle pain 2

Physical Examination Findings

• Hepatomegaly may be the only physical finding in the absence of advanced disease 1
• In simple steatosis without inflammation, physical examination is often entirely normal 1
• Spider angiomas, palmar erythema, splenomegaly, or ascites suggest progression to cirrhosis 1

Laboratory Abnormalities

Liver Enzymes

• Mildly elevated AST and/or ALT with AST:ALT ratio <1 is the most common pattern 1
• Normal or near-normal ALT does not exclude hepatic steatosis or even steatohepatitis - up to 50% of patients with NAFLD have normal liver chemistries 1
• The AST:ALT ratio may reverse to >1 in later stages of disease 1
• Alkaline phosphatase and/or gamma-glutamyltransferase may be mildly elevated 1
• Bilirubin typically remains normal unless advanced disease is present 1

Other Laboratory Findings

• Elevated international normalized ratio, hypoalbuminemia, or thrombocytopenia indicate cirrhosis or portal hypertension 1
• Mildly elevated serum ferritin is common and does not necessarily indicate iron overload 1

Imaging Findings

Ultrasound Characteristics

• Increased liver echogenicity compared to renal cortex is the hallmark finding 1
• Grading of steatosis on ultrasound 1:
  • Mild: Mild diffuse increase in liver echogenicity with clear definition of diaphragm and intrahepatic vessel walls
  • Moderate: Mild diffuse increase in liver echogenicity with obscuration of diaphragm and intrahepatic vessel walls
  • Severe: Marked increase in liver echogenicity with non-visualization of diaphragm and intrahepatic vessel walls
• Ultrasound has 84.8% sensitivity and 93.6% specificity for moderate-to-severe steatosis (>30% fat content), but sensitivity drops to 53.3-65% for mild steatosis 1
• Hepatorenal index (quantitative measurement) shows excellent correlation with fat fraction and is independent of BMI, inflammation, or fibrosis 1

CT and MRI Findings

• CT and MRI are more accurate than ultrasound for evaluating steatosis 1
• Decreased liver attenuation on CT or signal changes on MRI indicate fat accumulation 1, 3

Important Clinical Distinctions

Simple Steatosis vs. Steatohepatitis

• Simple hepatic steatosis (70-75% of cases) occurs without cellular injury or inflammation, explaining the absence of pain and minimal symptoms 1, 2
• Steatohepatitis (NASH) with inflammation and hepatocyte injury (25-30% of cases) may produce more symptoms than simple steatosis 1, 2
• The liver capsule lacks pain receptors for stretch or fat accumulation alone; pain typically requires inflammation, rapid enlargement, or capsular distension 2

Associated Metabolic Conditions

• Strong associations with obesity, type 2 diabetes, and metabolic syndrome should prompt evaluation for these conditions 1
• Presence of metabolic risk factors increases likelihood of steatosis even with normal liver enzymes 1

Common Pitfalls

• Do not exclude hepatic steatosis based on normal liver enzymes alone - imaging may be necessary in high-risk patients 1
• Do not assume elevated ferritin indicates hemochromatosis - it is commonly elevated in NAFLD as an epiphenomenon 1
• Ultrasound sensitivity decreases significantly with mild steatosis and in the presence of inflammation or fibrosis 1
• Incidentally discovered steatosis on imaging warrants assessment for metabolic risk factors even if liver biochemistries are normal 1