There are four main stages of non alcoholic fatty liver disease, the first of which is called simple fatty liver. This early-stage NAFLD, otherwise known as steatosis, is usually harmless and only detected if a test is being carried out for some other reason. For example, if a blood test comes back with high levels of liver enzymes, non alcoholic fatty liver disease may be suspected. An ultrasound or similar imaging test can then be conducted to confirm the diagnosis. Simple fatty liver is when there is a buildup of fat in the liver cells, but it is not causing any sort of inflammation or liver cell damage. Numerically speaking, fatty liver is when 5 to 10 percent of the liver’s weight is pure fat. People with this first stage of NAFLD can live with the condition for many years without experiencing any symptoms.
Non alcoholic steatohepatitis, or NASH, is the second stage of non alcoholic fatty liver disease and is much more serious than the first stage. This is when there is not only excess fat in the liver, but the liver has also become inflamed and may be accompanied by different degrees of scarring. NASH usually occurs in people between the ages of 40 and 60 years and is more common in women than in men. It also tends to affect individuals who suffer from obesity, diabetes, high cholesterol, or high triglycerides, although this is not a requirement. When left untreated, non alcoholic steatohepatitis can lead to severe liver scarring and cirrhosis.
The third stage of NAFLD is fibrosis, in which persistent inflammation in the liver leads to the formation of scar tissue, both around the liver itself as well as in the surrounding blood vessels. Liver stiffness is often one of the first warning signs of fibrosis. What separates fibrosis from cirrhosis is that the liver can still function normally, although the presence of fibrosis is often an indication that cirrhosis, otherwise known as advanced scarring, is starting to develop.
Cirrhosis is the fourth and final stage of NAFLD, and it is also the most severe. By definition, cirrhosis is when the liver shrinks and becomes both lumpy and scarred, leading to permanent scarring and hardening of the liver. It occurs after years of swelling and inflammation in the liver, and the damage it causes is irreversible. Symptoms of cirrhosis include fluid retention, internal bleeding, muscle wasting, and confusion. People with cirrhosis may require a liver transplant to survive, since the condition can lead to liver failure, liver cancer, and even death.
All in all, non alcoholic fatty liver disease is a highly prevalent disorder, affecting between 10 and 30 percent of the general population, as well as up to 90 percent of individuals who are obese. Furthermore, NAFLD is the most common chronic liver disorder in the United States. It is often asymptomatic, meaning that it produces or shows no symptoms, but when the disease progresses to NASH, fibrosis, or cirrhosis, it can quickly become a life threatening condition. The outlook for sufferers of NAFLD is generally good, since most cases of simple fatty liver can be reversed through a series of lifestyle changes, but if the condition progresses to stages 2, 3, or 4, complications can be fatal.
Resources:
- https://www.healthline.com/health/fatty-liver#stages
- https://www.nhs.uk/conditions/non-alcoholic-fatty-liver-disease/
- https://www.hopkinsmedicine.org/health/conditions-and-diseases/nonalcoholic-fatty-liver-disease
- https://liverfoundation.org/for-patients/about-the-liver/diseases-of-the-liver/non-alcoholic-fatty-liver-disease/#1503448220833-1dc16d27-63ab