Metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a condition that is characterized by a buildup of fat in the liver, which can lead to liver damage. The liver is part of the digestive system, and it helps break down food, store energy, and remove waste products. If more than 5 percent of the liver contains fat, the liver is considered to be fatty (steatotic).

MASLD is most common among middle-aged or older people, although younger people, including children, may also be affected. People with MASLD have liver steatosis along with at least one of the following features: higher body weight, type 2 diabetes, or one of several metabolic abnormalities. The abnormalities that are included in the diagnosis of MASLD are pre-diabetes (insulin resistance), high levels of fats (lipids) such as cholesterol and triglycerides in the blood, or high blood pressure (hypertension). MASLD is estimated to occur in up to 75 percent of adults with obesity or high levels of lipids in the blood and in up to 65 percent of adults with type 2 diabetes.

In people with MASLD, the fat deposits in the liver can cause increased levels of liver enzymes that can be detected during routine blood tests. Some affected individuals have abdominal pain or fatigue. During a physical examination, the liver may be found to be slightly enlarged. In people with MASLD, the liver problems are not caused by alcohol use disorder.

MASLD is slow to worsen, or it may not worsen at all. In many affected individuals, the buildup of fat in the liver can be reduced by adopting healthy habits. However, up to 30 percent of people with MASLD develop inflammation of the liver (metabolic dysfunction-associated steatohepatitis, also known as MASH), which can damage the liver. In people with long-term liver damage, normal liver tissue may be replaced with scar tissue (fibrosis), resulting in permanent liver disease (cirrhosis) and, eventually, liver failure. People with MASLD, MASH, and cirrhosis have a higher risk of developing liver cancer (hepatocellular cancer). People with MASLD are also at increased risk of developing additional health problems such as heart (cardiovascular) disease.