Understanding Nonalcoholic Steatohepatitis (NASH)

Nonalcoholic steatohepatitis, or NASH, is an advanced form of nonalcoholic fatty liver disease (NAFLD). NAFLD is a liver condition in which fat builds up in the liver in people who consume little to no alcohol. With NASH, fat builds up in the liver and causes inflammation and liver damage over time.¹

NASH is a slow-progressing disease. Because of this gradual damage to the liver, it often does not cause any noticeable symptoms until its later stages. If left untreated, it can progress to more severe liver problems, like cirrhosis, liver cancer, or liver failure.^1,2

It is also known as “MASH”

NASH is also known as MASH, or metabolic dysfunction-associated steatohepatitis. This name change was spearheaded by many national and international organizations, including the American Liver Foundation.³

The new name does not change how the disease is treated. But it does provide clearer guidance for potential screening options. And it may help identify who should be screened at earlier stages.³

The role of the liver

To understand NASH, it can be helpful to understand the role of the liver and its function. The liver plays a central role in maintaining your health and well-being. The liver performs more than 500 vital functions and communicates with other organs and systems in the body. The liver also:^4,5

• Breaks down and converts food to energy for your body to use
• Filters out harmful toxins and substances from the blood
• Produces bile, a greenish-yellow fluid that helps with digestion and absorption of fats in the small intestine
• Fights infections by making vital molecules involved in immune responses and removing bacteria from the bloodstream
• Stores essential nutrients like minerals, vitamins, and glycogen for when your body needs them

The liver is an incredibly resilient organ. This means it can make up for the damage it faces over time. But at a certain point, the damage becomes irreversible. And when fat builds up in the liver, as it does in NASH, it stops the liver from working as it should.⁵

Causes and risk factors of NASH

The exact cause of NASH is not fully understood. But it is often linked to other health conditions like obesity, diabetes, and high cholesterol levels. These risk factors contribute to the buildup of fat in the liver, which can lead to inflammation and further liver damage.²

Who does NASH affect?

NASH can affect anyone, but it is more common in people who have one or more of the health conditions mentioned above. It is often seen in adults, but it can also occur in children, especially those who are living with overweight or obesity.¹

How is NASH diagnosed?

Diagnosing NASH involves a combination of medical history, physical exam, and various tests. Tests may include:⁶

• Blood tests – These can detect elevated liver enzyme levels, which can mean there is liver inflammation or damage. These blood tests are also called liver function tests.
• Imaging tests – Imaging tests provide detailed pictures of the inside of the body. This can help show fat buildup in the liver and the level of liver damage. These tests include ultrasound, computed tomography (CT) scan, magnetic resonance imaging (MRI), and elastography.
• Liver biopsy – A liver biopsy is when a small sample of liver tissue is collected and examined under a microscope. This helps experts see what kind of damage is present in the liver. At this time, a liver biopsy is the only test that can prove a NASH diagnosis.

Because of the liver’s amazing resilience, early stages of liver damage can be reversed. That is why early diagnosis is so critical for NASH. The earlier you can get your risk factors under control, the better your prognosis will be.⁵

Managing and treating NASH

Managing NASH usually starts with making lifestyle changes such as:⁷

• Losing weight
• Eating a healthy diet
• Getting regular exercise
• Avoiding alcohol
• Managing co-existing medical conditions

In some cases, doctors may recommend medicines to help manage certain aspects of NASH, such as controlling blood sugar or reducing cholesterol levels. There is currently one drug approved to treat adults with NASH who have moderate to advanced liver scarring (fibrosis). This drug is called Rezdiffra™ (resmetirom). It is meant to be used along with a healthy diet and exercise.⁸

Several other drugs have been shown to lead to weight loss and improved diabetes control which also improve inflammation in the liver. These drugs include GLP-1 agonists like semaglutide (Ozempic®, Wegovy®, Rybelsus®) and tirzepatide (Mounjaro®). But they are not approved for use solely for NASH and you typically must have one of the other comorbidities (obesity, diabetes) to qualify.^9,10

If you suspect you may have NASH or think you may be at risk, get evaluated by a healthcare provider.