Nonalcoholic Fatty Liver Disease (NAFLD), Animation 

NAFLD and NASH: signs and symptoms, pathophysiology, risk factors, diagnosis, prevention and treatment. For patient education.
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Voice by : Marty Henne
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Non-alcoholic fatty liver disease, NAFLD, refers to abnormal fat accumulation in the liver that is NOT due to excessive alcohol consumption. NAFLD is very common - it is estimated to affect about 30% of the world population.
While the majority of cases are benign with no liver damage, some people may go on to develop liver inflammation, a condition known as non-alcoholic steatohepatitis, NASH, which may lead to destruction of liver tissues. Severe damage may cause scarring, resulting in liver cirrhosis, and eventually liver failure.
Most people with NAFLD have no symptoms, although some may present with fatigue, malaise, or pain or discomfort in the upper right abdomen. When NASH develops, symptoms may include weakness, jaundice, itchy skin, loss of appetite and nausea. In the advanced stage, widespread scarring of liver tissues may lead to decreased blood flow within the liver, causing high blood pressure in the hepatic portal vein that carries blood to the liver. This condition is known as portal hypertension. Portal hypertension may cause:
- abdominal distension,
- enlarged spleen,
- and formation of new blood vessels as alternative routes for blood to bypass the liver. Under high pressure, these small vessels can become engorged and form varices, which may rupture and bleed. Because the alternative vessels direct blood away from the liver, toxins that are normally removed by the liver can now reach the general circulation and pass into the brain, causing symptoms such as confusion, drowsiness, tremor, or even coma, in a condition known as hepatic encephalopathy.
Non-alcoholic fatty liver can develop for many reasons. The cause is complex and likely involves hormonal, lifestyle as well as genetic factors. However, the condition seems to associate with metabolic risk factors that also define metabolic syndrome, namely:
- being overweight or obese, especially in the abdomen,
- having high triglyceride or LDL levels in the blood,
- having high blood pressure,
- or having insulin resistance or glucose intolerance.
Because most cases are asymptomatic, NAFLD is typically suspected when routine health screening or tests done for other reasons suggest a liver problem, especially in a person with known risk factors. Heavy alcohol consumption must be excluded. Imaging studies may reveal presence of fat accumulation, but liver biopsy remains the gold standard for diagnosis.
While there is currently no specific treatment for NAFLD, the condition can be largely prevented or even reversed with lifestyle remedies, such as weight loss, healthy eating, and physical exercise. People with cirrhosis may require liver transplantation.