What Is Fatty Liver and Nonalcoholic Steatohepatitis?
Fatty liver, also known as nonalcoholic fatty liver disease, is characterized by a buildup of fat in the liver. For reasons that aren’t entirely clear, a person with fatty liver disease has an impairment in the system that delivers and removes fats from the liver, resulting in the accumulation of fat beyond the normal capacity of the liver. Such fat accumulation is common in obese people, occurring in over 40 percent of the obese population. It is also common among people with type 2 diabetes (who are often obese). In general, it is estimated that fatty liver occurs in about 20 percent of U. S. adults.
Fatty liver itself does not produce symptoms or pose any health threat. Many cases of the disorder improve after weight reduction. Some cases, however, progress to nonalcoholic steatohepatitis (NASH), a liver disorder that involves damage to the liver similar to that seen in alcoholic liver disease—though NASH occurs in the absence of alcohol abuse. Like alcoholic fatty liver disease, NASH is associated with liver fibrosis, the formation of scar tissue in the liver, which may progress to cirrhosis—an irreversible liver disease that is the tenth leading cause of death in the United States (Cirrhosis). Why some people with fatty liver go on to develop NASH is not clearly understood.
What Causes Fatty Liver and Nonalcoholic Steatohepatitis?
- Obesity is the leading risk factor for fatty liver and NASH. Abdominal adiposity (excessive amount of body fat stored in the abdomen compared to the hips and thighs) is also a risk factor.
- People with diabetes are at increased risk for fatty liver and NASH.
- Hyperlipidemia, and hypertriglyceridemia in particular, is another factor associated with the development of fatty liver and NASH.
- Certain medications, such as corticosteroids and estrogen, may contribute to the development of fatty liver and NASH.
- Jejunal bypass surgery—a procedure used for weight reduction—is another factor associated with NASH.
- Patients receiving total parenteral nutrition (TPN) are at increased risk for developing fatty liver and NASH.
- Heavy alcohol consumption
Symptoms of Fatty Liver and Nonalcoholic Steatohepatitis
- Neither fatty liver nor NASH commonly produce symptoms. When symptoms do occur, they include:
- Pain in the upper right quadrant of the abdomen
- Weakness and fatigue
- Weight loss (in NASH)
Prevention of Fatty Liver and Nonalcoholic Steatohepatitis
- Maintaining a healthy weight or losing weight, if necessary, may help prevent fatty liver or NASH from developing.
- It’s important to control blood sugar and lipid abnormalities.
Diagnosis of Fatty Liver and Nonalcoholic Steatohepatitis
- Most people with fatty liver and NASH see a physician for unrelated conditions. Liver disease is found incidentally during routine blood tests.
- Elevated liver enzymes—particularly in the presence of obesity or diabetes—suggest the diagnosis of fatty liver or NASH.
- Patient history and physical exam are necessary to determine history of alcohol use, and to rule out other possible causes of liver disease, such as viral hepatitis.
- Imaging studies, such as ultrasound, CT (computed tomography scan), or a MRI (magnetic resonance imaging scan), may be used to identify the presence of abnormal fat accumulation in the liver, but these techniques cannot distinguish between fatty liver and NASH. These tests are mostly used to rule out other causes of liver disease.
- A liver biopsy is the only method to confirm the diagnosis of fatty liver or NASH.
How Fatty Liver and Nonalcoholic Steatohepatitis Is Treated
- Weight loss is routinely recommended to keep NASH from progressing; however, data remains inconclusive regarding the usefulness of weight loss. Nevertheless, weight loss may be effective at relieving abdominal pain in symptomatic patients. Gradual weight loss is best as sudden weight loss is associated with an increase in fat accumulation.
- Alcohol should be avoided in patients with NASH.
- Choline supplementation is necessary in patients receiving TPN.
- A liver transplant may be considered for patients with cirrhosis.
- Medications (e.g., lipid lowering medications, insulin sensitizers)
- Anti-oxidant medications, anti-apoptotic medications and anti-cytokine medications to reduce liver inflammation
When to Call a Doctor
- Call a physician if you develop pain in the right upper quadrant of the abdomen.
Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference
Simeon Margolis, M.D., Ph.D., Medical Editor
Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50
Updated by Remedy Health Media