Definition & Facts

In this section:

• What is NAFLD?
• How common is NAFLD in children?
• Who is more likely to develop NAFLD?
• What are the complications of NAFLD?

What is NAFLD?

Nonalcoholic fatty liver disease (NAFLD) is a condition in which excess fat builds up in the liver. This buildup of fat is not caused by heavy alcohol use. When heavy alcohol use causes fat to build up in the liver, this condition is called alcohol-associated liver disease.

Two types of NAFLD are nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). Children typically develop one type of NAFLD or the other, although sometimes children with one form are later diagnosed with the other form of NAFLD. NAFL is a mild condition, and NASH is a more serious condition.

NAFL

NAFL is the form of NAFLD in which a child has increased fat in the liver but little or no inflammation or liver damage. NAFL typically doesn’t progress to cause liver damage or complications.

NASH

NASH is the form of NAFLD in which a child has inflammation of the liver and liver damage, in addition to fat in the liver. The inflammation and liver damage of NASH can cause fibrosis, or scarring, of the liver. NASH may lead to cirrhosis, in which the liver is scarred and permanently damaged. Cirrhosis can lead to liver cancer.

Experts are not sure why some children with NAFLD have NASH while others have NAFL.

How common is NAFLD in children?

NAFLD is the most common cause of chronic liver disease in children in the United States. Studies suggest that 5% to 10% of children have NAFLD.¹ NAFLD has become more common in children in recent decades, in part because childhood obesity has become more common.

Research suggests that 20% to 50% of children with NAFLD have the NASH form of the disease.¹

Who is more likely to develop NAFLD?

Children who have certain health problems, including obesity and conditions related to obesity, are more likely to develop NAFLD.

NAFLD is more common in older children than in younger children and more common in boys than in girls.

Although NAFLD occurs in children of all races and ethnicities, it’s most common in Hispanic children and Asian American children, followed by white children. NAFLD is less common in Black children.¹

NAFLD is more common in older children than in younger children and more common in boys than in girls.

What are the complications of NAFLD?

Children with NAFLD have a greater chance of developing liver complications or other health problems.

Liver complications

The majority of children with NAFLD have NAFL.¹ Children with NAFL typically don’t develop liver complications, although they have a higher risk for other health problems such as diabetes.

However, some children with NAFLD have NASH. NASH can lead to liver complications such as cirrhosis and liver cancer. If cirrhosis leads to liver failure, a liver transplant may be needed.

Compared with people who develop NAFLD during adulthood, people who develop NAFLD during childhood are more likely to have NASH and related complications or liver disease as adults. Children with NASH may develop cirrhosis during childhood.² However, the complications of cirrhosis, such as liver failure and liver cancer, usually arise in adulthood.

Other health problems

Children with NAFLD have a higher risk for certain health problems, including

• type 2 diabetes
• metabolic syndrome
• conditions that may be part of the metabolic syndrome, such as high blood pressure and abnormal levels of fats—cholesterol and triglycerides—in the blood

People with the metabolic syndrome have a greater chance of heart disease, stroke, and hardening of the arteries as adults.

References

Symptoms & Causes

What are the symptoms of NAFLD in children?

Usually, nonalcoholic fatty liver disease (NAFLD)—including nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH)—is a silent disease with few or no symptoms. Children may not have symptoms even if they develop cirrhosis due to NASH.

Once symptoms arise, however, a child may already have permanent liver damage. If children do have symptoms from NASH, they may feel tired, become tired easily, or have discomfort over the liver, in the upper right side of the abdomen.

What causes NAFLD in children?

Experts are still studying the causes of NAFLD. Research suggests that certain health problems, genes, and other factors may make some children more likely to develop NAFLD.

Health problems

Children with the following health problems are more likely to develop NAFLD

• overweight or obesity.
• insulin resistance or type 2 diabetes.
• high blood pressure.
• abnormal levels of fats in the blood, which may include
  • high levels of triglycerides.
  • abnormal levels of cholesterol—typically high total cholesterol, high LDL cholesterol, or low HDL cholesterol.
• metabolic syndrome, or one or more traits of metabolic syndrome. Metabolic syndrome is a group of traits and medical conditions linked to overweight and obesity. Doctors typically define metabolic syndrome in children as a combination of three or more of the following features
  • large waist size.
  • high levels of triglycerides in the blood.
  • low levels of HDL cholesterol in the blood.
  • high blood pressure.
  • higher-than-normal blood glucose levels or a diagnosis of type 2 diabetes.

Doctors may not be able to diagnose metabolic syndrome in children younger than age 10. Children in this age group may still have traits of metabolic syndrome.

Experts do not know for sure why some children with NAFLD have NAFL while others have NASH. Research suggests that NASH is more common in children who have both NAFLD and type 2 diabetes.³

Genes

Certain genes may increase a child’s chance of developing NAFLD. These genes may explain why NAFLD is more common in Hispanic and Asian American children than in Black children. Genes may also explain why NAFLD sometimes runs in families.

Experts are still studying the genes that may play a role in NAFLD.

Other factors

Scientists are studying other factors that may play a role in causing or worsening NAFLD in children. These include

• birthweight. Research suggests that children who had a high or low birthweight are more likely to develop NAFLD.
• changes in the microbiome—the bacteria in the digestive tract that help with digestion. Studies have found differences between the microbiomes of children who have NAFLD and those who do not.
• diets high in fructose—a sugar that is part of table sugar and is also commonly added to sweeten drinks and foods. Studies suggest that diets high in fructose may increase the risk of NAFLD.

Is NAFLD the only cause of fatty liver in children?

Fatty liver may have causes other than NAFLD. If medical tests suggest that a child has a buildup of fat in the liver, the doctor may ask questions and order tests for other causes.

Other causes of fatty liver in children include

• disorders, called lipodystrophies, that cause a child’s body to use or store fat improperly
• celiac disease
• rapid weight loss or malnutrition
• some medicines, including those used to treat mental disorders, nervous system disorders, or skin conditions
• exposure to some toxins
• rare genetic diseases, such as Wilson disease and hypobetalipoproteinemia
• alcohol-associated liver disease—damage to the liver and its function due to excessive alcohol consumption

Reference

Diagnosis

How do doctors diagnose NAFLD in children?

Doctors use medical and family history, a physical exam, and tests to diagnose nonalcoholic fatty liver disease (NAFLD)—including nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH)—in children.

Medical and family history

The doctor will ask about the child’s history of health problems that increase the chance of developing NAFLD, such as

• overweight or obesity
• insulin resistance or type 2 diabetes
• high blood pressure
• high levels of triglycerides or abnormal levels of cholesterol in the blood
• metabolic syndrome

The doctor will ask about the presence of these health problems or NAFLD in the child’s family. Children with a family history of these health problems are more likely to develop NAFLD.

The doctor will also ask about diet and lifestyle factors that may make a child more likely to develop NAFLD and NASH, such as a lack of physical activity, eating a diet high in sugar and starch, or drinking sugary beverages.

Physical exam

During a physical exam, a doctor typically checks weight and height to calculate the child’s body mass index. The doctor will also look for physical signs of NAFLD or NASH, such as

• an enlarged liver
• signs of insulin resistance, such as darkened skin patches over the child’s neck or armpits
• signs of cirrhosis, such as an enlarged spleen

What tests do doctors use to diagnose NAFLD in children?

Doctors use blood tests, imaging tests, and sometimes liver biopsy to diagnose NAFLD in children, to tell the difference between NAFL and NASH, and to check for other liver problems.

Blood tests

A health care professional may take a blood sample from the child and send the sample to a lab. The doctor may suspect NAFLD if the blood test shows increased levels of the liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST). The doctor may perform additional blood tests to find out if the child has other health conditions that may increase liver enzyme levels.

Imaging tests

If a blood test shows that a child has increased liver enzyme levels, the doctor may order imaging tests of the liver. While imaging tests cannot confirm a diagnosis of NAFLD or tell the difference between NAFL and NASH, imaging tests may show signs of other liver problems or may suggest that fat is present in the liver.

A commonly used imaging test is ultrasound. Ultrasound bounces safe, painless sound waves off organs to create an image of their structure. Ultrasound tests do not use radiation and are not painful.

Elastography is a newer type of test that may help determine whether a child has advanced liver fibrosis, or scarring. In some cases, doctors may order an elastography test to measure the stiffness of a child’s liver. Increased liver stiffness may be a sign of fibrosis.

Types of elastography tests include special ultrasound and magnetic resonance imaging (MRI) tests. MRI uses radio waves and magnets to produce detailed images of organs and soft tissues without using x-rays. Researchers are still studying the use of these tests to help diagnose NAFLD in children.

Liver biopsy

Liver biopsy is the only test that can prove a diagnosis of NAFLD, tell whether a child has NAFL or NASH, and show clearly how severe the disease is, including how much fibrosis—or scarring—is present. However, doctors may not recommend this test for all children with suspected NAFLD. In some cases, doctors recommend a liver biopsy to rule out other liver diseases. Doctors may also recommend a biopsy for children who have a greater chance of having NASH or scarring of the liver.

During a liver biopsy, a doctor will take a small piece of tissue from the liver. A pathologist will examine the tissue under a microscope to look for signs of damage and signs of the cause of liver disease.

Treatment

How do doctors treat NAFLD in children?

Doctors may recommend that children with overweight or obesity gradually lose weight to treat nonalcoholic fatty liver disease (NAFLD)—either nonalcoholic fatty liver (NAFL) or nonalcoholic steatohepatitis (NASH). Weight loss is the most effective way to reduce fat, inflammation, and fibrosis—or scarring—in the liver. Doctors may suggest that young children try to maintain their weight as their height increases. Most important is to avoid further excess weight gain.

To manage weight and help improve NAFLD, you can help your child

• improve healthy eating habits
• avoid drinking beverages that have added sugar
• avoid “fast foods” high in sugar, starch, and fat
• be more physically active

You can also help your child by being a role model in both healthy eating and physical activity.

No medicines have been approved to treat NAFLD—either NAFL or NASH—in children. Researchers are studying medicines that may improve these conditions.

For safety reasons, talk with your child’s doctor before your child uses dietary supplements—such as mixtures of vitamins, minerals, nutritional supplements, and herbal medicines—or any other complementary or alternative medicines or practices. Some herbal remedies can actually damage a child’s liver.

How do doctors treat the complications of NASH?

If NASH leads to cirrhosis, doctors can treat the health problems caused by cirrhosis with medicines, minor medical procedures, and surgery. If cirrhosis leads to liver failure, a child may need a liver transplant.

How can parents and caretakers help prevent NAFLD in children?

Making sure that a child eats a healthy diet, limits portion sizes, and maintains a healthy weight can help prevent NAFLD.

Eating, Diet, & Nutrition

How can a child’s diet help prevent or treat NAFLD?

Eating a healthy diet, limiting portion sizes, and maintaining a healthy weight can help prevent NAFLD in children.

For children with overweight or obesity who have NAFLD, doctors may recommend gradual weight loss. Eating a healthy diet, avoiding beverages that have added sugar, and being more active can help manage weight and improve NAFLD.

Eating a healthy diet, limiting portion sizes, and maintaining a healthy weight can help prevent NAFLD in children.

If a child has NAFLD, the parent or caretaker should talk with a doctor about the child’s diet. Making sure that children receive proper nutrition is important for growth and development. The doctor may refer the child to a dietitian to help plan a well-balanced diet. Check on the cost of a dietitian’s services and whether your health insurance may pay for some or all of these services.

Clinical Trials

In this section:

• Why are clinical trials with children important?
• How do I decide if a clinical trial is right for my child?
• What aspects of NAFLD are being studied in children?
• What clinical studies for NAFLD are available for child participants?
• What have we learned about NAFLD in children from NIDDK-funded research?

The NIDDK conducts and supports clinical trials in many diseases and conditions, including liver diseases. The trials look to find new ways to prevent, detect, or treat disease and improve quality of life.

Why are clinical trials with children important?

Children respond to medicines and treatments differently than adults. The way to get the best treatments for children is through research designed specifically for them.

We have already made great strides in improving children’s health outcomes through clinical trials—and other types of clinical studies. Vaccines, treatments for children with cancer, and interventions for premature babies are just a few examples of how this targeted research can help. However, we still have many questions to answer and more children waiting to benefit.

The data gathered from trials and studies involving children help doctors and researchers

• find the best dose of medicines for children
• find treatments for conditions that only affect children
• treat conditions that behave differently in children than in adults
• understand the differences in children as they grow

How do I decide if a clinical trial is right for my child?

We understand you have many questions, want to weigh the pros and cons, and need to learn as much as possible. Deciding to enroll in a study can be life changing for you and for your child. Depending on the outcome of the study, your child may find relief from their condition, see no benefit, or help to improve the health of future generations.

Talk with your child and consider what would be expected. What could be the potential benefit or harm? Would you need to travel? Is my child well enough to participate? While parents or guardians must give their permission, or consent, for their children to join a study, the children must also agree to participate, if they are capable (verbal). In the end, no choice is right or wrong. Your decision is about what is best for your child.

The National Institutes of Health (NIH) is committed to ensuring you get all the information you need to feel comfortable and make informed decisions. The safety of children remains the utmost priority for all NIH research studies. For more resources to help decide if clinical trials are right for your child, visit Clinical Trials and You: Parents and Children.

What aspects of NAFLD are being studied in children?

Researchers study many aspects of nonalcoholic fatty liver disease (NAFLD), nonalcoholic fatty liver (NAFL), and nonalcoholic steatohepatitis (NASH), including

• understanding how NAFLD begins and progresses in children
• identifying genes that play a role in causing NAFLD
• improving the diagnosis of NAFLD and NASH in children

Watch a video of NIDDK Director Dr. Griffin P. Rodgers explaining the importance of participating in clinical trials.

What clinical studies for NAFLD are available for child participants?

You can view a filtered list of clinical studies on NAFLD in children that are federally funded, open, and recruiting at www.ClinicalTrials.gov. You can expand or narrow the list to include clinical studies from industry, universities, and individuals; however, the NIH does not review these studies and cannot ensure they are safe. If you find a trial you think may be right for your child, talk with your child’s doctor about how to enroll.

What have we learned about NAFLD in children from NIDDK-funded research?

The NIDDK has supported many research projects to learn more about NAFLD and NASH in children. For example, the NIDDK’s NASH Clinical Research Network (NASH CRN) has conducted studies to advance understanding of the causes, development, complications, and treatment of NASH in children and adults.

NASH CRN studies include the Treatment of Nonalcoholic Fatty Liver Disease in Children (TONIC) trial. The TONIC trial found that the natural form of vitamin E—the type of vitamin E that comes from food sources and is not synthetic (laboratory-made)—improved the most severe form of fatty liver disease in some children. More research is needed to determine whether treatment with vitamin E causes long-term risks.

Recent NASH CRN research has explored many aspects of NAFLD and NASH in children, including

• the risk of health problems such as abnormal levels of fats in the blood and type 2 diabetes in children with NAFLD
• different subtypes of NASH that occur in children
• the relationship between NAFLD and the microbiome
• new methods to measure the severity of NAFLD without a liver biopsy
• possible treatments for NAFLD and NASH