Non-alcoholic steatohepatitis (NASH)

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was reviewed on February 1, 2022.

Non-alcoholic steatohepatitis (NASH) is a serious condition that results from excess fat in the liver.

What is NASH?

NASH is a severe form of non-alcoholic fatty liver disease (NAFLD). NASH results from fat buildup—not associated with alcohol use, as the name indicates—and causes the liver to become inflamed and damaged, which may be a risk factor for developing liver cancer.

While as many as 24 percent of people in the United States have NAFLD, NASH is less common, with an estimated 1.5 percent to 6.5 percent of American adults affected.

Some people with NASH have more severe cirrhosis, which can lead to liver cancer. Cirrhosis occurs when the liver is scarred, causing permanent damage. However, NASH patients who don’t have cirrhosis may also develop primary liver cancer.

NASH symptoms

Patients can have NASH with no or very few symptoms. It's possible to not even have symptoms if NASH triggers cirrhosis.

Symptoms, if any, may include:

  • Tiredness
  • Discomfort in the liver area, on the right side of the abdomen

In rare cases, children develop NASH, with symptoms such as vomiting and tenderness in their abdomen.

Causes of NASH

Doctors don't know why some people with NAFLD develop NASH and cirrhosis. However, there are some factors that may increase the risk for developing NASH.

NASH is more likely in people with the following conditions:

  • Large waist
  • High blood pressure
  • High blood sugar or type 2 diabetes
  • High levels of triglycerides in their blood
  • Low levels of good cholesterol (HDL) in their blood
  • Poor diet

Researchers are studying different microorganisms in the intestines and how the body absorbs nutrients for possible causes. Other areas of research on the causes of NASH include:

  • Immune system response to excess fat in the liver
  • Liver or fat cells releasing toxic chemicals called cytokines
  • Liver cells destroying themselves
  • Unstable molecules known as free radicals

Some less common conditions that may contribute to the development of NASH, according to the American Liver Foundation, include:

  • Rapid weight loss
  • Hepatitis C
  • Improper storage of fat as a result of a medical condition
  • Exposure to certain toxins
  • Polycystic ovarian syndrome (PCOS), which affects female hormones
  • Certain medications, such as Cordarone® and Pacerone® (amiodarone), glucocorticoids, Rheumatrex® and Trexall® (methotrexate), synthetic estrogens, Nolvadex® and Soltamox® (tamoxifen)

Although children can develop NASH, people are at greater risk as they age. NASH is also seen at higher rates among those of Hispanic or Asian descent.

Is NASH hereditary?

People who inherit a variation in the PNPLA3 gene, which provides instructions for making a protein found in fat and liver cells, may be more susceptible to NASH. Researchers are studying this and other genetic changes that may contribute to people developing NASH and its complications.

NASH diagnosis and detection

A NASH diagnosis involves multiple steps, including a physical examination, blood tests, imaging tests, and possibly a liver biopsy.

Medical history and physical exam

The care team will start with the patient's medical history to determine whether he or she has any conditions that may lead to NAFLD and NASH. These include:

  • Being overweight or obese
  • Having type 2 diabetes or insulin resistance
  • Having high levels of triglycerides or cholesterol
  • Having metabolic or insulin resistance syndrome

The doctor performs a physical exam to feel whether the patient's liver is enlarged and to look for signs of insulin resistance such as darkened skin patches on the knuckles, elbows and knees.

The doctor looks for signs of cirrhosis, which include:

  • Enlarged spleen
  • Fluid in the abdomen
  • Muscle loss

Blood tests

The patient will likely undergo blood tests to look for high levels of liver enzymes such as:

  • Alanine aminotransferase (ALT)
  • Aspartate aminotransferase (AST)

Other blood tests may show whether the patient has liver fibrosis or scarring.

Imaging studies

The doctor is also likely to order imaging tests, which can show whether the patient has fat in his or her liver or liver scarring. These may include:

Imaging tests also may be used to determine whether the patient has liver nodules or lumps.

The only conclusive test for NASH is a liver biopsy. A biopsy will show whether the patient has severe liver disease, and it rules out other liver diseases. During a biopsy, a doctor takes a sample of tissue from the liver and sends it to the pathology laboratory, where it’s examined under a microscope.

NASH treatments

The U.S. Food and Drug Administration hasn’t approved medications to treat NASH. Research is underway to develop drugs that could treat this condition.

To reduce fat in the liver, people who are currently overweight should try to lose weight. Aim to lose at least 3 percent to 5 percent of body weight, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

Being active, even if weight loss isn't possible, may also help treat NASH.

It’s important to treat related conditions, including diabetes, high blood pressure and high cholesterol. It’s also recommended that people with NASH avoid alcohol.

NASH can lead to cirrhosis. Cirrhosis can lead to complications, some of which can be treated with medications. If cirrhosis leads to liver failure or liver cancer, the patient may need a liver transplant.

NASH prognosis

The majority of NASH patients don’t develop severe liver issues, and most people who have NASH live as long as those who don’t have the disease. 

Keep in mind that the survival rate for non-alcoholic steatohepatitis depends on a variety of factors, including the patient’s age, overall health and the extent of the disease, so the patient should always talk to his or her care team about his or her individual prognosis.

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