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Fatty Liver Disease (Hepatosteatosis): Diagnosis, Causes & More

What Is Fatty Liver Disease (Hepatosteatosis)

Hepatosteatosis, or hepatic steatosis, is an accumulation of fat in the liver. Also called fatty liver, hepatic steatosis is a term attributed to numerous conditions. Most often, it is used in reference to fatty liver disease.

In general, a healthy liver should contain little to no fat. For most people, a small amount of fat in the liver causes no major problems. High levels of fat in the liver, however, can lead to diabetes, heart attack, and stroke. In advanced cases of fatty liver disease, cirrhosis (liver damage) may occur, increasing the risk of developing liver cancer.

Screening for cirrhosis, particularly in patients with risk factors such as viral hepatitis, obesity, or alcohol use should be mandatory.

Nicknamed the ‘silent killer’, nonalcoholic fatty liver disease is predicted to surpass hepatitis B & C as the leading cause of cirrhosis and main reason for liver transplants by 2020.

How is Fatty Liver (Hepatosteatosis) Diagnosed

Hepatosteatosis usually causes no symptoms. As a result, most cases are found incidentally, through routine liver function tests or imaging of the abdomen. Unfortunately, this means that many patients do not receive a diagnosis until the disease has already advanced and cirrhosis is developing.

The most common imaging procedures used to diagnose hepatic steatosis include ultrasonography, computed tomography, transient elastography, and magnetic resonance imaging. In inconclusive cases, a biopsy may be necessary.

Familiarity with the way different patterns of fat accumulation appear in radiographic images is essential for detecting and evaluating the stage of hepatic steatosis. Accurate image interpretation requires the expertise of a subspecialty radiologist

Distinguishing the difference between fat deposition and fatty liver in radiographic imaging can be challenging. Mischaracterization of fatty liver as 'fatty infiltration' is another possible diagnostic pitfall. Liver lesions should also be taken into consideration during image interpretation. Hepatic adenomas, hepatocellular carcinomas, and, occasionally, focal nodular hyperplasias may have microscopic fat content, causing confusion. To prevent diagnostic errors, a subspecialty radiologist should interpret imaging tests.

Fatty Liver Ultrasound

There are two main indicators of hepatic steatosis (fatty liver) in a liver ultrasound:

  • the liver echogenicity exceeds that of renal cortex and spleen
  • there is attenuation of the ultrasound wave, loss of definition of the diaphragm, and poor delineation of the intrahepatic architecture

To avoid false-positive interpretations, a hepatic steatosis diagnosis should only be given via ultrasound alone if both indicators are present. Generally, MRI is considered the preferred modality for accurate diagnosis.

Types of Fatty Liver Disease (Hepatosteatosis)

Fatty liver disease can be split up into two types: alcoholic hepatic steatosis (alcoholic fatty liver disease) and nonalcoholic hepatic steatosis (nonalcoholic fatty liver disease).

Alcoholic Fatty Liver Disease (Alcoholic Hepatosteatosis)

Alcoholic hepatic steatosis, also called alcoholic fatty liver disease, occurs as a result of chronic, heavy alcohol consumption. As fat builds up inside the liver cells, liver function becomes difficult.

Many people with alcoholic hepatic steatosis do not experience any symptoms. However, pain and discomfort in the right upper abdomen are common side effects in advenced cases where the liver becomes enlarged. Once diagnosed, those with alcoholic hepatic steatosis usually see improvement after they stop drinking alcohol. In the case that a patient continues to drink, they run the risk of developing alcoholic hepatitis and alcoholic cirrhosis. Cirrhosis can then develop into liver cancer.

Non-Alcoholic Fatty Liver Disease (Non-Alcoholic Hepatosteatosis)

Non-alcoholic hepatic steatosis, also called nonalcoholic fatty liver disease, is the most common chronic liver disease in the Western world. As the name suggests, nonalcoholic liver disease refers to fat accumulation in the liver (hepatic steatosis) that was not brought on by the use of alcohol.

According to Johns Hopkins, about 10% to 20% of Americans have NAFLD. About 2% to 5% have NASH. It is the most common form of liver disease.

Most often, nonalcoholic hepatosteatosis is a result of obesity or metabolic syndrome - a condition typically characterized by high blood pressure, poor ability to use the hormone insulin, high blood sugar, high cholesterol, and excess body fat around the waist. While it can occur in all ages, hepatosteatosis is typically found in people aged 40 to 50 years old.

It is heavily influenced by lifestyle (poor diet high in sugar and carbohydrates, chronic excessive calorie intake, sedentary activity) and is distinct from fatty liver diseases caused by alcohol.

There are two types of nonalcoholic hepatic steatosis: simple fatty liver and nonalcoholic steatohepatitis (NASH).

Simple fatty liver

Most people with nonalcoholic hepatic steatosis have simple fatty liver. Generally non-threatening, simple fatty liver is a condition of fat in the liver - but without inflammation in the liver or damage to the liver cells. It is typically asymptomatic and does not cause any liver function problems. However, if fat is present in the liver for an extensive period of time, the liver cells can become inflamed and simple fatty liver can develop into nonalcoholic steatohepatitis.

Non-alcoholic steatohepatitis (NASH)

Nonalcoholic steatohepatitis is the most severe form of nonalcoholic hepatic steatosis. It accounts for about 20% of nonalcoholic steatohepatitis cases. While also a condition of fat in the liver, those with nonalcoholic steatohepatitis have liver inflammation and, usually, liver cell damage as well.

Those with NASH are at high risk of developing fibrosis and cirrhosis, which can ultimately lead to liver cancer. It’s often nicknamed a ‘silent killer’ because patients can live it with it for years without experiencing any symptoms.

Risk Factors

Heavy alcohol consumption is the main cause of alcoholic hepatic steatosis. Obesity and metabolic syndrome are some of the main risk factors for developing nonalcoholic hepatic steatosis. While alcohol consumption is not the direct cause of nonalcoholic fatty liver, it can complicate the situation.

Other possible contributing risk factors for non-alcoholic hepatic steatosis include:

  • Insulin resistance
  • High blood sugar
  • Type 2 diabetes
  • High levels of unhealthy fats, especially triglycerides
  • Thyroid or pituitary gland issues

A healthy diet and regular exercise can help prevent non-alcoholic hepatosteatosis.


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In this article...

How is Fatty Liver (Hepatosteatosis) Diagnosed Fatty Liver Ultrasound Types of Fatty Liver Disease (Hepatosteatosis) Alcoholic Fatty Liver Disease (Alcoholic Hepatosteatosis) Non-Alcoholic Fatty Liver Disease (Non-Alcoholic Hepatosteatosis) Risk Factors

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