What is Nonalcoholic Fatty Liver (Fatty Liver)?
Non-alcoholic fatty liver disease (NAFLD) is a condition that includes a range of liver issues. These are identified by the presence of fat in the liver (hepatic steatosis) seen in medical scans or tissue samples (histology). This happens without other causes such as heavy alcohol drinking, long-term use of certain medicines, or inherited diseases. The definition of heavy alcohol drinking isn’t always clear. In clinical trials for a related condition, non-alcoholic steatohepatitis (NASH), it’s defined as having over 14 standard drinks a week for women and over 21 for men on average.
Non-alcoholic fatty liver disease is often discovered by accident during medical imaging or when complications arise. In Western countries, about 20 to 30% of people have this condition. It’s the liver result of a condition called metabolic syndrome. About half to 70% of people with diabetes also have this liver condition.
The disease can progress in several stages, starting with simple fat accumulation, inflammation of the liver with fat (steatohepatitis), scarring (fibrosis), severe scarring (cirrhosis), and could even lead to liver cancer. This disease usually remains silent if there’s only fat accumulation. If there’s liver damage or inflammation with or without scarring, it’s termed non-alcoholic steatohepatitis (NASH).
What Causes Nonalcoholic Fatty Liver (Fatty Liver)?
Conditions like obesity, diabetes, abnormal cholesterol levels, resistance to insulin, and a group of conditions called metabolic syndrome, are known to contribute to the development of a condition called non-alcoholic fatty liver disease (NAFLD). There’s also evidence suggesting a connection between exposure to a chemical called inorganic arsenic and the development of NAFLD, an indication of this is an increase in a component of the blood known as alanine transferase (ALT).
NAFLD is closely associated with metabolic syndrome, which includes several conditions that increase the risk of heart disease. This association means that people with NAFLD have a higher chance of having heart disease. Furthermore, NAFLD can lead to serious liver conditions like cirrhosis, where the liver is severely scarred, and liver cancer, which can both contribute to mortality.
Risk Factors and Frequency for Nonalcoholic Fatty Liver (Fatty Liver)
Non-alcoholic fatty liver disease (NAFLD) is becoming more common, especially in Western countries. There are several reasons for this increase, including the growing problem of obesity, lack of physical activity, unhealthy food habits, and people living longer. Diagnosing NAFLD is challenging with only an ultrasound, so we likely underestimate how often it actually occurs.
- Between 80% and 90% of obese adults have NAFLD.
- 30% to 50% of people with diabetes might have NAFLD.
- People with high levels of fats in their blood, called hyperlipidemia, have a 90% or higher chance of having NAFLD.
- About 3% to 10% of children may have NAFLD.
- Among children who are obese, 40% to 70% might have NAFLD.
Signs and Symptoms of Nonalcoholic Fatty Liver (Fatty Liver)
People with non-alcoholic fatty liver disease (NAFLD) might show a range of generic symptoms, long before the condition is diagnosed. A large number of patients don’t exhibit any symptoms. Fatigue is usually one of the first signs that appear. Other early symptoms can include general discomfort or aches in the upper abdomen, feeling excessively thirsty, bloating, and trouble sleeping.
- Fatigue
- Upper abdominal discomfort or aches
- Excessive thirst
- Bloating
- Trouble sleeping
When NAFLD advances to more serious conditions such as NASH-associated cirrhosis, end-stage liver disease, or hepatocellular carcinoma (HCC), symptoms may include:
- Nausea
- Vomiting
- Yellowing of the skin and eyes (jaundice)
- Itchy skin (pruritis)
- Fluid buildup in the abdomen (ascites)
- Memory problems
- Easy bruising or bleeding
- Loss of appetite
The most commonly observed clinical sign is a mild to moderate enlargement of the liver (hepatomegaly). In advanced stages, the disease may show signs of end-stage liver disease, such as:
- Yellowing of the skin and eyes (jaundice)
- Spider-shaped blood vessels on the skin (spider angiomas)
- Redness in the palms of the hands (palmar erythema)
- Swollen blood vessels in the belly that look like a spider’s web (caput medusae)
- Enlarged male breasts (gynecomastia)
- Thickening of the tissue in the palm causing the fingers to contract (Dupuytren contracture)
- Fluid buildup in the abdomen (ascites)
- Tiny red spots or patches on the skin (petechiae)
Testing for Nonalcoholic Fatty Liver (Fatty Liver)
Non-alcoholic fatty liver disease (NAFLD) is often indicated by slightly raised levels of aminotransferases, a type of enzyme, in your blood. However, most patients with this condition have normal liver enzyme levels. Sometimes, the amounts of two specific enzymes, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), are compared – in NAFLD patients, the AST to ALT ratio is usually less than 1. Another liver enzyme, gamma-glutamyl transferase (GGT), can indicate a worsening condition and increased risk of death if it’s increased in patients with NAFLD. Other signs of disease progression include low albumin (a protein produced by the liver) levels, high bilirubin (a waste product) levels, low platelet count, and prolonged prothrombin (a blood-clotting protein) time due to liver function impairment.
Abdominal ultrasounds are often used to identify a fatty liver, but the definitive test for diagnosing NAFLD is a liver biopsy. There are also non-invasive scoring systems to predict the likelihood of developing NAFLD, especially in patients with metabolic syndrome – a group of conditions that increases your risk of diseases, including NAFLD. One of these scoring systems, called the NAFLD in metabolic syndrome (MS) score, takes into account factors like body mass index (BMI), the AST/ALT ratio, type 2 diabetes, and obesity. Using this system, individuals with a score of less than 3 have a relatively low risk of developing NAFLD, while those with a score of 5 or more have a much higher risk. There are other complex scoring systems too, like the NAFLD fibrosis score, FIB-4 index, and more, that can provide additional information about the condition.
Treatment Options for Nonalcoholic Fatty Liver (Fatty Liver)
People with non-alcoholic fatty liver disease (NAFLD), even without a severe form called NASH, are advised to make lifestyle changes. This is crucial as these individuals typically have metabolic issues and are prone to developing heart diseases. It is suggested that those with simple fatty liver aim to lose about 3 to 5% of their body weight, and those with NASH should target a weight loss of about 7 to 10%.
It’s also important to manage other underlying risk factors properly. For instance, high cholesterol levels should be controlled with cholesterol-lowering drugs known as statins, which also help protect against heart disease. Controlling high blood pressure and maintaining suitable blood sugar levels is equally necessary. For a more thorough understanding of this topic, look for discussions on hepatitis and non-alcoholic steatohepatitis in the transplant hepatology section.
People with NASH should be under the care of liver specialists or gastroenterologists. If NASH develops into a more serious condition known as cirrhosis, semi-annual ultrasound scans are recommended to check for liver cancer. Currently, several clinical trials are in progress to explore new treatments for NAFLD, including anti-fibrotic, anti-apoptotic, and immune therapies.
What else can Nonalcoholic Fatty Liver (Fatty Liver) be?
Non-alcoholic fatty liver disease (NAFLD) is a condition that can share symptoms with other health issues. Doctors need to consider these similar conditions before making their final diagnosis. Some of these conditions that can also lead to conditions akin to NAFLD include:
- Alcoholic liver disease, which is caused by excessive drinking
- Hepatitis C, especially type 3
- Wilson’s disease, a rare genetic disorder
- Certain medications, such as amiodarone, methotrexate, tamoxifen, glucocorticoids, valproate, and anti-retroviral drugs used to treat HIV
- Reye syndrome, a rare but serious illness that can affect the liver and brain
- Mitochondrial hepatopathies, liver disease related to problems with the cells’ power sources, the mitochondria
- Kwashiorkor/anorexia nervosa, severe malnutrition conditions
- Mitochondrial disorders, genetic diseases affecting cellular energy production
By considering all of these possibilities, doctors can ensure that they diagnose non-alcoholic fatty liver disease accurately.
What to expect with Nonalcoholic Fatty Liver (Fatty Liver)
People with non-alcoholic fatty liver disease (NAFLD) have a higher chance of dying compared to others. Most often, they die due to heart-related issues caused by metabolic malfunctions in their bodies. In fact, more NAFLD patients die from heart-related issues than from liver problems.
NAFLD is a disease that slowly worsens over time. While the condition can start as simple steatosis, a reversible and non-worsening state, it can turn to a condition called NASH which can further progress to scarring of the liver called cirrhosis.
According to a 13-year study, cirrhosis developed in 41% of the patients studied. In another study that analyzed several other studies, it was found that in groups of patients with NAFLD or NASH who had little to no cirrhosis, the risk of developing liver cancer was very small – between 0 to 3% over 20 years. But for those with NASH who already had cirrhosis, the risk dramatically increased to 2.4% over seven years.
Possible Complications When Diagnosed with Nonalcoholic Fatty Liver (Fatty Liver)
The main complications associated with non-alcoholic fatty liver disease (NAFLD), listed from most to least common, are:
- Cardiovascular disease
- Liver cancer, also known as hepatocellular carcinoma
- End-stage liver disease, which is the most severe form of the disease
The seriousness of these complications is directly related to how severe the liver disease is, according to its stage and grade.
Preventing Nonalcoholic Fatty Liver (Fatty Liver)
Teaching patients about their food choices and portion sizes is very important. The main focus of treatment is education about nutrition and lifestyle. Every time a person sees their healthcare provider, it should be an opportunity to discuss and review their food choices, portion sizes, and exercise routines, including exercises that involve bearing weight. The American Diabetes Association and other groups provide great advice about diet and lifestyle.
