Investigations of fatty liver

Initial laboratory tests include:

• liver enzymes
  • aminotransferase levels
    • in non alcoholic fatty liver disease –
      • alanine aminotransferase (ALT) levels exceeding those of aspartate aminotransferase (AST) – AST:ALT <0.8 (>0.8 with more advanced disease)
    • in alcoholic fatty liver disease
      • AST:ALT ratio >1.5
  • gamma glutamyl transferase (GGT)
  • alkaline phosphatase (ALP) – may be increased
• MCV – increased
  • raised MCV and serum gamma GT suggest alcohol abuse; note that GGT may be raised in non-alcoholic steohepatitis which is not associated with alcohol abuse
• hepatic screen for other causes of abnormal liver function tests including screening for hepatitis B, hepatitis C and haemochromatosis
• liver imaging
  • ultrasound,
    • is the first-line imaging technique
    • causes increased echogenicity on ultrasound (compared with the lower echogenicity of the spleen or renal cortex)
    • sensitivity and specificity of detecting fatty infiltration decreases as BMI increases
  • CT or MRI will demonstrate fatty infiltration
• liver biopsy
  • needle biopsy confirms the diagnosis and excludes irreversible disease

Additional laboratory tests may be considered in patients with chronically elevated liver enzyme levels or in those with a family history of cirrhosis and includes:

• autoimmune studies - antinuclear antibody, smooth muscle antibody
• α1-antitrypsin
• ceruloplasmin
• thyroid-stimulating hormone levels
• NICE suggest to consider using the enhanced liver fibrosis (ELF) test in people who have been diagnosed with non-alcoholic fatty liver disease (NAFLD) to test for advanced liver fibrosis (4)

Reference:

• (1) Wilkins T et al. Nonalcoholic fatty liver disease: diagnosis and management. Am Fam Physician. 2013;88(1):35-42.
• (2) Sattar N, Forrest E, Preiss D. Non-alcoholic fatty liver disease. BMJ. 2014;349:g4596
• (3) Adams LA, Angulo P, Lindor KD. Nonalcoholic fatty liver disease. CMAJ. 2005;172(7):899-905.
• (4) NICE (July 2016). Non-alcoholic fatty liver disease (NAFLD): assessment and management