Non-alcoholic Fatty Liver Disease and Non-Alcoholic Steatohepatitis
Non-alcoholic fatty liver disease (NAFLD) is a condition in which fat builds up in the liver. In some cases this accumulation of fat can cause inflammation of the liver and eventually lead to permanent scarring (cirrhosis), which can seriously impair the liver’s ability to function. Unlike alcoholic fatty liver disease (alcoholic steatohepatitis), NAFLD can occur in people who drink no alcohol or drink only in moderation. NAFLD is, however, closely associated with obesity and diabetes. The consequences of the condition can be grave and NAFLD represents a major global public health problem.
How to diagnose NAFLD?
A healthy liver contains very little or no fat. NAFLD occurs in people who do not drink a significant amount of alcohol (20 grams per day for men and 10 grams per day for women) and who do not have a viral infection or other specific cause of liver disease. NAFLD is diagnosed when accumulation of fat in the organ exceeds 5% of hepatocytes (the cells that make up the majority of the liver). NAFLD is sometimes called a ‘silent disease’ as even in its late stages it may have no symptoms and may only be diagnosed after liver function tests have revealed an abnormality.
Diagnosis:
- Blood test (AST and ALT usually elevated)
- Imaging: Usually presence of fat seen on ultrasound, CT scan or MRI
- Liver biopsy
- Liver fibroscan (non-invasive test) has replaced liver biopsy in majority of case
What are the stages of NAFLD and treatment options?
From simple fatty liver to irreversible cirrhosis NAFLD can progress from steatosis, to non-alcoholic steatohepatitis (NASH), to fibrosis and then to cirrhosis. Effective treatment options in NAFLD include weight reduction, dietary changes and physical activity. In its early stages, NAFLD can be treated through diet and lifestyle changes, such as losing weight. Cirrhosis, the most severe stage of NAFLD, usually only occurs after years of liver inflammation and can lead to a range of complications, including liver failure and hepatocellular carcinoma (HCC). Between 10 and 30% of patients with NAFLD have NASH that can progress to cirrhosis.
What are the risk factors for developing NAFLD?
NAFLD is usually seen in people who are overweight or obese. Those with insulin resistance, type 2 diabetes, high blood pressure or high blood lipids (cholesterol and triglycerides) are also more likely to develop NAFLD. Studies have reported NAFLD prevalence rates of between approximately 43 and 70% in adults with type 2 diabetes. Obesity and diabetes are on the rise around the world. Obesity triggers inflammatory pathways in the brain and adipose tissue, resulting in the disruption of insulin levels. Over time, fat accumulates in the liver (as well as muscles and blood vessels), which exacerbates systemic insulin resistance.
The heavy toll of NAFLD
NAFLD increases the risk of overall mortality and of mortality related to cardiovascular disease and liver disease. Controlling the etiological factors helps to reverse the condition as long as there is no permanent scarring in the liver. Persistent inflammation can cause scarring and cirrhosis.