One in three U.S. adults have nonalcoholic fatty liver disease.
Most people are familiar with conditions like high blood pressure and diabetes – and understand that they’re connected with obesity. Fewer people, however, have heard of nonalcoholic fatty liver disease, which is the most common liver disorder in much of the developed world. NAFLD affects roughly 10 percent of children and a third of all adults in the United States alone. Soon, it’s expected to be the most common reason for liver transplantation.
What is fatty liver disease?
Put simply, fatty liver occurs when too much fat is stored in liver cells. Over time, the extra fat in the liver cells can lead to the development of inflammation and scarring, a condition called nonalcoholic steatohepatitis. People with NASH are at highest risk for developing cirrhosis (liver failure) and may eventually need a liver transplant. The time it takes for someone to progress from simple fatty changes to NASH to cirrhosis can vary, however. There is also no guarantee that NAFLD will progress. Many people – in fact most people – may have fatty liver for years or decades without symptoms or complications.
Because there are typically no symptoms, NAFLD is most often suspected when the liver enzymes are elevated on routine blood testing. Some people are also identified incidentally when they have an ultrasound, CT or MRI test for a separate reason.
It’s important to note that routine liver tests and imaging studies are insensitive, meaning that they cannot diagnose everyone. These tests are also nonspecific, meaning that multiple conditions – like infections, autoimmune disease, medications, metabolic disorders and genetic conditions – can also produce abnormal results. Therefore, your physician should only make a diagnosis of NAFLD after carefully excluding other types of liver disease and considering a liver biopsy.
Liver biopsy is the only definitive way to diagnose NAFLD. Of course, not everyone needs a liver biopsy and such decisions are typically best made on a case-by-case basis between the family and physician. A liver biopsy is more likely to be performed in children with persistently abnormal liver tests, very high liver tests, a concern for other liver conditions (like autoimmune disease) or due to the presence of specific risk factors.
Many research groups, including ours at the Children’s Hospital at Montefiore, are looking for novel, non-invasive ways to identify NAFLD, NASH and fibrosis (scarring). These future tests may limit the need for liver biopsy and allow doctors to monitor the disease as it progresses.
Who gets NAFLD and why?
The exact cause of NAFLD isn’t known, but it’s clearly associated with being overweight or obese. Other risk factors include insulin resistance and diabetes, gender, age, diet and ethnicity. Recent research indicates that genetics also play a large role. For example, Mexican Americans are at particularly high risk of developing fatty liver and NASH due to mutations in a specific gene, PNPLA3. Interestingly, a different mutation in the same gene seems to protect against fatty liver and NASH among African American children. Other gene mutations are also associated with NAFLD, though not as strongly as PNPLA3.
|Source: Never Heard of Nonalcoholic Fatty Liver Disease? You and Your Kids May Have It | For Better | US News|