nonalcoholic%20fatty%20liver%20disease
NONALCOHOLIC FATTY LIVER DISEASE

Nonalcoholic fatty liver disease is having excessive fat (in the form of triglycerides) accumulation not due to excessive alcohol consumption or other secondary causes.

It is considered as a hepatic manifestation of metabolic syndrome.

Progression of nonalcoholic fatty liver disease is variable.

Diagnosis

  • Patient with persistent abnormal liver enzymes, with insulin resistance &/or metabolic syndrome risk factors should be screened for nonalcoholic fatty liver disease (NAFLD)
  • Criteria for diagnosing non-alcoholic fatty liver disease:
    • Presence of steatosis in either imaging or histology studies
    • Alcoholic liver disease has been ruled out (daily alcohol consumption did not exceed 30 g for men & 20 g for women)
    • Other liver diseases (eg chronic hepatitis B/C, autoimmune liver disease) & metabolic or hereditary liver diseases have been ruled out

Classification

 Clinical Entities

  • Nonalcoholic Fatty Liver (NAFL)
    • Benign, nonprogressive entity
  • Nonalcoholic steatohepatitis (NASH)
    • Can progress to cirrhosis or even hepatocellular carcinoma



History

  • Patients are usually asymptomatic until the condition progresses to liver cirrhosis
  • Sometimes have vague symptoms of fatigue, malaise, & abdominal discomfort
  • Detailed patient history of alcohol consumption should be sought
  • Dietary & physical activity habits should be assessed because these influence the development & progression of nonalcoholic fatty liver disease (NAFLD)

Physical Examination

  • Physical findings to (rule out other causes of liver disease) assess progressive liver disease are presence of spider angiomas, acites, hepatomegaly, splenomegaly, palmar erythema, jaundice, hepatic encephalopathy

Laboratory Tests

  • Shows mild elevation of transaminases (ALT, AST)
  • Levels of serum transaminases are helpful in screening for nonalcoholic fatty liver disease (NAFLD) but these do not identify severity of NAFLD
  • Hepatitis B surface antigen, hepatitis C virus antibody or HCV-RNA should be done to exclude viral hepatitis as the cause of the fatty liver findings without chronic alcohol intake
  • Other findings include elevated hyaluronic acid that indicates fibrosis & low platelet counts with evidence of liver dysfunction such as elevated serum bilirubin & ammonia indicative of cirrhosis
Liver Biopsy
  • Diagnostic procedure considered in patients who are at increased risk to have nonalcoholic steatohepatitis (NASH) & advanced fibrosis or are suspected of having coexisting chronic liver diseases where there is a need to distinguish NASH from other chronic liver diseases
  • Essential in diagnosing & staging NASH

Histology

  • Nonalcoholic fatty liver disease (NAFLD) is characterized by macrovesicular steatosis in 5% of hepatocytes
  • Histologically NAFL is characterized by hepatic steatosis with no evidence of hepatocellular injury or no ballooning degeneration
  • Nonalcoholic steatohepatitis (NASH) is characterized histologically by hepatic steatosis associated with evidence of liver cell injury (ballooning degeneration) & lobular inflammation

Imaging

  • Used to detect fatty changes
  • Abdominal ultrasound is the most common method of assessing hepatic steatosis
    • Preferred diagnostic procedure for nonalcoholic fatty liver disease (NAFLD) as it provides additional hepatobiliary information aside from presence of steatosis
  • Computed tomography & magnetic resonance imaging (MRI) seem to be more objective & more sensitive techniques for the quantification of steatosis, but MRI is still less widely available & much more expensive

Screening For Alcohol Abuse or Dependency

  • Patient’s alcohol consumption should be established to diagnose nonalcoholic fatty liver disease
    • Threshold is <20g/day in women, <30g/day in men
  • To evaluate the alcohol consumption of the patient, appropriate specialized questionnaires or scoring systems should be used
  • Tool most often used to assess alcohol dependency is “CAGE” questionnaire which refers to lifetime occurrence of the following:
    • Cutting down on drinking
    • Annoyance at others’ concerns about drinking
    • Feeling Guilty about drinking
    • Use of alcohol as an Eye opener in the morning
  • CAGE confirms clinically relevant alcohol consumption if at least one of the above questions is answered positively & if the Alcohol Use Disorders Identification Test (AUDIT) score is higher than 8
  • Other screening tools include the Michigan Alcoholism Screening Test (MAST) & the Lifetime Drinking History

Evaluation of Steatosis

Validated Steatosis Scores
  • Used in large scale screening for presence of steatosis
  • Nonalcoholic fatty liver disease fibrosis score is a widely validated scoring system for predicting the severity of fibrosis
    • It is based on 6 readily assessable clinical variables that include age, body mass index (BMI), hyperglycemia, platelet count, albumin & the aspartate transaminase/alanine transaminase ratio that is calculated using a published formula
  • Enhanced liver fibrosis (ELF) test is used to determine the presence of liver fibrosis
    • ELF score of ≥10.51 with nonalcoholic fatty liver disease indicates advanced liver fibrosis
    • Can also be used to test if pharmacological therapy is effective
  • Other scoring systems are Fatty Liver Index (FLI), SteatoTest & nonalcoholic fatty liver disease liver fat score
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