Definition of Fatty Liver
Fatty liver, also known as fatty liver disease (FLD), is a reversible condition where large vacuoles of triglyceride fat accumulate in liver cells via the process of steatosis (i.e. abnormal retention of lipids within a cell). Despite having multiple causes, fatty liver can be considered a single disease that occurs worldwide in those with excessive alcohol intake and those who are obese (with or without effects of insulin resistance). The condition is also associated with other diseases that influence fat metabolism. Morphologically, it is difficult to distinguish alcoholic FLD from nonalcoholic FLD, and both show microvesicular and macrovesicular fatty changes at different stages.
Accumulation of fat may also be accompanied by a progressive inflammation of the liver (hepatitis), called steatohepatitis. By considering the contribution by alcohol, fatty liver may be termed alcoholic steatosis or nonalcoholic fatty liver disease (NAFLD), and the more severe forms as alcoholic steatohepatitis (part of alcoholic liver disease) and Non-alcoholic steatohepatitis (NASH).
Cause of Fatty Liver
Fatty liver causes are different for each person affected by fatty liver disease. It is the deterioration of the liver due to fat buildup or excess of fat. Most people don’t experience any symptoms and only diagnosed when testing for another condition. However, if the condition is left untreated, then this could lead to serious complications.
Fatty liver (FL) is commonly associated with alcohol or metabolic syndrome (diabetes, hypertension, obesity and dyslipidemia), but can also be due to any one of many causes:
- Abetalipoproteinemia, glycogen storage diseases, Weber-Christian disease, acute fatty liver of pregnancy, lipodystrophy
- Malnutrition, total parenteral nutrition, severe weight loss, refeeding syndrome, jejunoileal bypass, gastric bypass, jejunal diverticulosis with bacterial overgrowth
Drugs and toxins
- Amiodarone, methotrexate, diltiazem, expired tetracycline, highly active antiretroviral therapy, glucocorticoids, tamoxifen, environmental hepatotoxins (e.g., phosphorus, mushroom poisoning)
- Inflammatory bowel disease, HIV, hepatitis C (especially genotype 3), and alpha 1-antitrypsin deficiency
Signs and Symptoms of Fatty Liver
Fatty liver disease is asymptomic, especially in the beginning. If the disease advances — which is usually over a period of years, or even decades — it can cause vague problems such as:
- weight loss
- abdominal discomfort
Up to 10% of cirrhotic alcoholic FLD patients will develop hepatocellular carcinoma. The overall incidence of liver cancer in nonalcoholic FLD has not yet been quantified, but the association is well established.
Risk Factors for Fatty Liver
A wide range of diseases and conditions can increase your risk of nonalcoholic fatty liver disease, including:
- glycogen storage diseases
- Weber-Christian disease
- acute fatty liver of pregnancy
- total parenteral nutrition
- severe weight loss
- refeeding syndrome
- jejunoileal bypass
- gastric bypass
- jejunal diverticulosis with bacterial overgrowth
- expired tetracycline
- highly active antiretroviral therapy
- glucocorticoids, tamoxifen
- environmental hepatotoxins (e.g., phosphorus, mushroom poisoning)
- Inflammatory bowel disease
- hepatitis C (especially genotype 3)
- alpha 1-antitrypsin deficiency
Diagnosis of Fatty Liver
Most individuals are asymptomatic and are usually discovered incidentally because of abnormal liver function tests or hepatomegaly noted in unrelated medical conditions. Elevated liver biochemistry is found in 50% of patients with simple steatosis. The serum alanine transaminase level usually is greater than the aspartate transaminase level in the nonalcoholic variant and the opposite in alcoholic FLD (AST:ALT more than 2:1).
Blood tests. During routine blood tests, elevations in certain liver enzymes may show up. These might include alanine aminotransferase (ALT) or aspartate aminotransferase (AST).
Imaging studies. Imaging studies are often obtained during the evaluation process. Ultrasonography reveals a “bright” liver with increased echogenicity. Medical imaging can aid in diagnosis of fatty liver; fatty livers have lower density than spleens on computed tomography (CT), and fat appears bright in T1-weighted magnetic resonance images (MRIs). No medical imagery, however, is able to distinguish simple steatosis from advanced NASH. Histological diagnosis by liver biopsy is sought when assessment of severity is indicated.
Liver biopsy. The only way to confirm a diagnosis of fatty liver disease is with a liver biopsy. This is usually done once other causes have been ruled out. After application of local anesthesia, a tiny piece of liver is removed to be examined under a microscope for signs of fat, inflammation, and damaged liver cells. If inflammation or damage is not present, the diagnosis is simply a fatty liver.
Prevention from Fatty Liver
To reduce your risk of nonalcoholic fatty liver disease, try to:
- Maintain a healthy weight, if you are over-weight, loose weight safely. This usually means losing no more than half to one kilogram (one to two pounds) a week
- Lower your triglycerides through diet, medication or both
- Avoid alcohol
- Control your diabetes, if you have it
- Choose a balanced, healthy diet
- Increase your physical activity
- Get regular check-ups from a doctor who specialises in liver care
- Avoid drugs and toxins like amiodarone, methotrexate, diltiazem, expired tetracycline, highly active antiretroviral therapy, glucocorticoids, tamoxifen, environmental hepatotoxins (e.g., phosphorus, mushroom poisoning)
Treatment of Fatty Liver
The treatment of fatty liver depends on its cause, and generally, treating the underlying cause will reverse the process of steatosis if implemented at an early stage. Two known causes of fatty liver disease are an excess consumption of alcohol, and a prolonged diet containing foods with a high proportion of calories coming from lipids. For the patients who have non-alcoholic fatty liver disease with pure steatosis and no evidence of inflammation, a gradual weight loss is often the only recommendation. In more serious cases medications that decrease insulin resistance, hyperlipidemia as well as those that induce weight loss have been shown to improve liver function.
New findings about the role of bacteria in the development of fatty liver disease may lead to still other options for treatment, such as by counteracting unbalanced diets with probiotics. These are dietary supplements containing healthy live bacteria or yeasts.
If cirrhosis becomes severe, a liver transplant may be needed. A surgeon removes the damaged liver and replaces it with a healthy one.