Diagnosis of NAFLD & NASH in Children
How do doctors diagnose NAFLD and NASH in children?
Doctors use medical and family history, a physical exam, and tests to diagnose nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) in children.
Medical and family history
The doctor will ask about the child’s history of health conditions that increase the chance of developing NAFLD and NASH, 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
- the metabolic syndrome
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
- an enlarged liver
- 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.
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