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Fatty Liver Disease

Overview

Fatty liver disease refers to the condition in which an extra amount of fat gets accumulated in your liver. The liver is a vital organ located in the right upper quadrant of the abdomen, whose function is to detoxify metabolites, synthesize proteins, hormones, bile, and biochemicals needed for digestion, growth, and metabolism. Normally, the liver has only a little amount of fat. When the percentage of fat in the liver exceeds 5-10% of the liver’s weight, it is known as fatty liver disease or liver steatosis. In most people, it does not cause serious issues; however, in around 7-30% of people, the disease progresses to inflammation and damage called steatohepatitis and may further progress to scarring of the liver called liver cirrhosis, in which normal functioning liver tissue is replaced by scarred tissue and fibrosis and is no longer able to perform its functions properly. Liver cirrhosis may ultimately result in liver failure or liver cancer.

Fatty liver disease is very common in the USA and is most commonly caused by excess alcohol consumption. It can also be due to obesity and an increased intake of fatty food. The presence of metabolic syndrome, which includes diabetes mellitus, hypertension, hyperlipidemia, are among the risk factors that can predispose to fatty liver disease.

By adopting a healthy lifestyle and avoiding alcohol, fatty liver disease can be prevented and even reversed. 

Causes

Fatty liver disease has several causes; heavy alcohol consumption, metabolic syndrome (obesity, high blood pressure, diabetes, hyperlipidemia), fatty liver of pregnancy, glycogen storage diseases, malnutrition, severe weight loss, some medicines like glucocorticoids, amiodarone, tamoxifen, methotrexate, highly active antiretroviral therapy, etc. The mechanism through which these disorders cause fatty liver disease is complex and still under research, but they all seem to involve defective or interrupted fatty acid metabolism. 

Types

The two main types of fatty liver disease are:

1-      Alcoholic liver disease: This type results from heavy alcohol consumption. Alcohol results in the production of toxic substances like aldehydes during its metabolism in the liver. Heavy drinking is defined by NIAAA as follows: consuming more than 4 drinks on any day or more than 14 drinks per week for men, while consuming more than 3 drinks on any day or more than 7 drinks per week for women. This disease affects around 5% of people in the U.S.

2-      Nonalcoholic fatty liver disease (NAFLD): As the name implies, this type is not caused by heavy drinking. However, obesity and the presence of metabolic syndrome have been implemented in its development. One in three adults and one in 10 children are affected in the United States by this type. 

Epidemiology

Around 25%-35% of the general population of the USA is affected by Steatosis. It affects all age groups; however, the level of alcohol toxicity increases with age. Women develop a more severe form of disease even at lower doses than men. Although fatty liver develops in around 90%-100% of heavy alcohol users, only about 10%-20% develop alcoholic hepatitis and cirrhosis. 80% of obese patients are recorded to have Nonalcoholic fatty liver disease. The chronic liver disease affected Japanese Americans and Latinos more than white and African Americans.

Risk Factors

Following are the risk factors that may increase the chances of chronic liver disease.

  • Excessive alcohol consumption.
  • Being overweight or obese.
  • Having diabtetes mellitus
  • Having high blood pressure
  • Having increased amounts of triglycerides in your blood.
  • Suffering from some diseases like glycogen storage diseases, celiac disease, HIV, hepatitis C, inflammatory bowel disease, abetalipoproteinemia, etc.
  • Family history
  • Using certain medicines like methotrexate, amiodarone, alpha methyldopa. 

Signs And Symptoms

Most people do not show any signs and symptoms. However, the signs and symptoms may appear over several days or even years, especially in people with progressive disease involving liver inflammation. The initial symptoms are due to hepatic insufficiency; however, later, the symptoms result from complications of the disease process, which involves the fibrosis of the liver structure. Signs and symptoms are as follows:

  • Tiredness and weakness
  • Loss of appetite
  • Anemia
  • Nausea
  • Weight loss
  • Jaundice
  • Itchy skin
  • Easy bleeding or bruising
  • Swelling in your lower legs and feet, called edema
  • Breasts enlargement in males (Gynecomastia)
  • Changing pattern of hair distribution
  • Atrophy of testicles
  • Fluid accumulation in your abdomen (ascites)

Differential Diagnosis

Some other diseases may mimic the presentation of fatty liver disease;

  • Autoimmune Hepatitis
  • Drug-Induced Hepatotoxicity
  • Hemochromatosis
  • Viral hepatitis like hepatitis A, B, C, D , E
  • Liver cancer
  • Glycogen storage diseases
  • Liver abscess
  • Syphilis of the liver
  • Cystic diseases of the liver
  • Tuberculosis of the liver
  • Trematode or other parasitic diseases.
  • Tropical liver

Diagnosis

It takes several years for fatty liver disease to show fibrosis and the resulting signs and symptoms. Sometimes the disease is diagnosed accidentally by liver function tests or on ultrasound. The diagnosis is made by a detailed history and a thorough physical examination. You may be advised to undergo a few investigations like:

  • Blood tests: Complete blood picture to assess for anemia, number of blood cells, liver function tests to determine the inflammation of the liver, coagulation profile, electrolytes and renal profile, tests for hepatitis C and B viruses, genetic testing for hereditary diseases, etc.
  • Imaging: Ultrasound, CT, and MRI scans can be used to assess the degree of fibrosis. The latest imaging test to determine the elasticity of the liver has been used lately called Magnetic resonance elastography (MRE).
  • Biopsy: A sample of your liver tissue is taken out through a needle under local anesthesia and sent to the laboratory to check for the extent and severity of the fibrosis.

Prognosis

Fatty liver disease may be reversible with losing weight and cessation of alcohol use, or both. However, patients with continued drinking may develop steatohepatitis, progress to liver fibrosis and cirrhosis, and may ultimately develop end-stage liver disease that could be life-threatening. Studies have shown that 30% of the patients with Nonalcoholic fatty liver disease may show progression, 30% may remain stable, while 30% may improve.

Treatment

Fatty liver disease has no specific treatment. Alcohol abstinence is the first and foremost step towards treatment.

Improvement in the disease is seen after a weight loss of 7% using diet control and exercise. However, weight loss of up to 10% is recommended. Although bariatric surgery usually performed for morbid obesity is not recommended to treat fatty liver disease, studies have shown improvement after the procedure. Treatment of co-morbid illnesses should be given like diabetes, hyperlipidemia, etc. Studies have shown an improvement in liver histology by taking Vitamin E 800 IU/day. 

Prevention

Following lifestyle changes can be adopted to prevent cirrhosis.

  • Avoid drinking alcohol
  • Consuming a healthy diet rich in vitamins, minerals, omega 3 fatty acids, antioxidants and avoiding fatty and fried food
  • Bodyweight should be maintained according to BMI by taking a balanced diet and regular exercise.
  • Take regular treatment and follow-ups for diseases like diabetes, hypertension, hyperlipidemia.
  • Get to know your family history and adopt healthy lifestyle changes from the beginning.
  • Employ regular exercises to improve inactivity, muscle cramps, and wasting.

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on May 18, 2023.

References

Nonalcoholic Fatty Liver Disease (NAFLD) & NASH 

https://www.niddk.nih.gov/health-information/liver-disease/nafld-nash

Prospective Study of Outcomes in Adults with Nonalcoholic Fatty Liver Disease

https://www.nejm.org/doi/full/10.1056/nejmoa2029349

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