Nonalcoholic fatty liver disease (NAFLD) is a condition in which excess fat is stored 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 alcoholic liver disease.
Two types of NAFLD are simple fatty liver and nonalcoholic steatohepatitis (NASH). Simple fatty liver and NASH are two separate conditions. 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. Simple fatty liver is a mild condition, and NASH is a more serious one.
Simple fatty liver
Simple fatty liver is the form of NAFLD in which a child has increased fat in the liver but little or no inflammation or liver cell damage. Simple fatty liver typically doesn’t progress to cause permanent liver damage or complications.
NASH is the form of NAFLD in which a child has hepatitis—inflammation of the liver—and liver cell damage, in addition to fat in the liver. Inflammation and liver cell damage can cause fibrosis, or scarring, of the liver. If the damage and scarring are severe enough, NASH may lead to cirrhosis or liver cancer.
Experts do not know for sure why some children with fat in the liver have NASH while others have simple fatty liver alone.
How common are NAFLD and NASH in children?
NAFLD is the most common cause of chronic liver disease in children in the United States. Researchers estimate that close to 10 percent of U.S. children ages 2 to 19 have NAFLD.1 NAFLD has become more common in children in recent decades, in part because childhood obesity has become more common.
In a study of NAFLD in children, about 23 percent of those with excess fat in the liver had NASH.1
Who is more likely to develop NAFLD or NASH?
Children who have certain conditions, including obesity and conditions that are related to obesity, are more likely to develop NAFLD or NASH.
NAFLD and NASH are more common in older children than in younger children. NAFLD is more common in boys than in girls. However, among children with NAFLD, girls and boys are equally likely to have NASH.
Although NAFLD and NASH occur in children of all races and ethnicities, these conditions are most common in Hispanic children and Asian American children, followed by Caucasian children. NAFLD and NASH are less common in African American children.1
What are the complications of NAFLD and NASH?
Children with NAFLD and NASH have a greater chance of developing liver complications and other health problems.
The majority of children with NAFLD have simple fatty liver.1 Children with simple fatty liver 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—either simple fatty liver or NASH—have a higher risk for certain health problems, including
Persons with the metabolic syndrome have a greater chance of heart disease, stroke and hardening of the arteries as adults.
Symptoms & Causes
What are the symptoms of NAFLD and NASH in children?
Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are typically silent diseases 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 and NASH in children?
Experts are still studying the causes of NAFLD and NASH. Research suggests that certain genes may make some children more likely to develop NAFLD.
Children with the following health conditions are also more likely to develop NAFLD or NASH:
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. People with metabolic syndrome are more likely to develop type 2 diabetes and heart disease. Experts think NAFLD may be closely linked to metabolic syndrome. Doctors typically define metabolic syndrome in children as a combination of three or more of the following features:
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 simple fatty liver while others have NASH. Research suggests that NASH is more common in children who have both NAFLD and type 2 diabetes.3
Certain genes may also increase a child’s chance of developing NASH. These genes may explain why NASH is more common in Hispanic and Asian American children than in black or African American children. Experts are still studying how the genes act to cause NAFLD and NASH.
Less common causes of NAFLD and NASH in children
Less common causes of NAFLD and NASH in children include
inherited disorders that cause a child’s body to use or store fat improperly
The doctor will ask about the presence of these conditions, NAFLD, or NASH in the child’s family. Children with a family history of these conditions are more likely to develop NAFLD and NASH.
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.
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
signs of insulin resistance, such as darkened skin patches over the child’s neck or armpits
signs of cirrhosis, such as jaundice, a yellow color of the skin or whites of the eyes
What tests do doctors use to diagnose NAFLD and NASH in children?
Doctors use blood tests, imaging tests, and sometimes liver biopsy to diagnose NAFLD and NASH in children and to check for other liver problems.
A health care professional may take a blood sample from the child and send the sample to a lab. The doctor may suspect NAFLD or NASH 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.
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 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.
Other imaging tests include elastography, a special type of ultrasound, and magnetic resonance imaging (MRI), which 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 is the only test that can prove a diagnosis of NAFLD or NASH and show clearly how severe the disease is. 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 greater chance of having NASH or scarring of the liver.
During a liver biopsy, a doctor will take a piece of tissue from the liver. A pathologist will examine the tissue under a microscope to look for signs of damage or disease.
A doctor performs a liver biopsy at a hospital or an outpatient center. A health care professional will tell the child and the child’s parent or caretaker how the child should prepare for a liver biopsy. The child may need to stop taking certain medicines to prepare. The child may be asked not to eat or drink anything for 8 hours before the procedure. During the procedure, the child may receive a local anesthetic, sedatives, and pain medicine.
During the biopsy, the child will lie on a table, right hand resting above his or her head. The doctor will numb the area where he or she will insert the biopsy needle with a local anesthetic and then use the needle to take a small piece of liver tissue.
How do doctors treat NAFLD and NASH in children?
Doctors recommend that children who are overweight or obeselose weight to treat NAFLD and NASH. Weight loss is the most effective way to reduce fat in the liver; inflammation; and fibrosis, or scarring. Doctors may suggest that young children try to maintain their weight as their height increases. Most important is to avoid further weight gain.
To manage weight and help improve NAFLD, you can help your child
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 and NASH in children. Researchers are studying medicines that may improve these conditions.
A study by the National Institute of Diabetes and Digestive and Kidney Diseases’ NASH Clinical Research Network found that treatment with vitamin E may improve NASH in some children.4 Researchers are still studying whether vitamin E is safe and effective as a possible treatment for NASH in children. Children should not take vitamin E without talking with a doctor first.
If NASH leads to cirrhosis, doctors can treat the health problems caused by cirrhosis with medicines, operations, and other medical procedures. If cirrhosis leads to liver failure, a child may need a liver transplant.
How can parents and caretakers help prevent NAFLD and NASH in children?
Making sure that a child eats a healthy diet, limits portion sizes, and maintains a healthy weight can help prevent NAFLD and NASH.
Eating, Diet, & Nutrition
How can a child’s diet help prevent or treat NAFLD or NASH?
Eating a healthy diet, limiting portion sizes, and maintaining a healthy weight can help prevent NAFLD and NASH in children.
For children who have NAFLD or NASH and are overweight or obese, 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 or NASH.
If a child has NAFLD or NASH, 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.
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and other components of the National Institutes of Health (NIH) conduct and support research into many diseases and conditions.
What are clinical trials, and what role do children play in research?
Clinical trials are research studies involving people of all ages. Clinical trials look at new ways to prevent, detect, or treat disease. Researchers also use clinical trials to look at other aspects of care, such as improving quality of life. Research involving children helps scientists
identify care that is best for a child
find the best dose of medicines
find treatments for conditions that only affect children
treat conditions that behave differently in children
understand how treatment affects a growing child’s body
This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases
(NIDDK), part of the National Institutes of Health. The NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by the NIDDK is carefully reviewed by NIDDK scientists and other experts.
The NIDDK would like to thank:
Jeffrey B. Schwimmer, M.D., University of California, San Diego, School of Medicine