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Non-Alcoholic Fatty Liver Disease

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Overview

Non-alcoholic fatty liver disease (NAFLD) describes the excess accumulation of fat in the liver (steatosis) which is not due to excessive alcohol consumption or other secondary causes. NAFLD is strongly associated with insulin resistance.

NAFLD often progresses through the following stages:

  • Hepatic steatosis – fatty accumulation in the liver without liver function disturbance
  • Non-alcoholic steatohepatitis (NASH) – steatosis combined with inflammation
  • Steatohepatitis – liver fibrosis
  • Cirrhosis – formation of scar tissue and end-stage liver disease

Epidemiology

  • NAFLD is the most common cause of abnormal liver blood tests in the UK
  • Prevalence increases with increasing age
  • Prevalence is highest in males aged 40-65 years

Risk Factors

Presentation

Most patients have no symptoms but have deranged liver function tests. Features may be:

Differential Diagnoses

  • Patients may be drinking alcohol higher than the recommended limits
  • AST: ALT ratio is usually >2 in alcoholic liver disease

Investigations

Screening is not routinely recommended, even in patients who may be at an increased risk. The following investigations are performed if the liver blood tests are found to have incidental derangements:

  • Non-invasive scoring systems – ideal first investigation, especially in primary care:
    • These assess the risk of developing liver fibrosis in patients with NAFLD
    • Examples are the enhanced liver fibrosis (ELF) test, NAFLD fibrosis score (NFS), and Fibrosis-4 (FIB-4)
  • Liver ultrasound:
    • May show signs of fatty changes (e.g. hyper-echogenic bright imaging)
  • FibroScan:
    • A non-invasive device that can assess the extent of liver fibrosis and cirrhosis by measuring the degree of liver stiffness – often used in secondary care
  • Liver biopsy:
    • May be considered for a definitive diagnosis

Management

Overview

  • 1st-line: lifestyle changes, including weight loss if necessary
  • Other options such as bariatric surgery may be considered

Monitoring and Patient Advice

Monitoring

  • Patients have their cardiovascular disease risk factors assessed annually
  • The risk of liver fibrosis is monitored every 3 years through ELF, NFS, or FIB-4 

Patient Advice

  • Patients should avoid excess alcohol consumption and should be offered help with this if necessary

Complications

Prognosis

  • The prognosis depends on the stage of the disease
  • Those with steatosis have a good prognosis with gradual weight loss and alcohol abstinence
  • The prognosis worsens with steatohepatitis

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