Fatty liver (medical term: steatosis hepatis) is a pathological change in the liver. It occurs when the body produces or receives more fats from outside than it can break down or remove from the liver.
Certain fats (triglycerides) are then increasingly deposited in the liver tissue, which leads to a gradual fatty degeneration of the liver cells (hepatocytes). Doctors also refer to this excess fat in the liver as fatty liver disease or steatosis.
The transition from a healthy liver to a fatty liver is fluid. Doctors only speak of a fatty liver when
- more than 50 percent of the liver cells have fat deposits or
- the proportion of fat in the liver accounts for more than 10 percent of the total weight of the liver.
Transition from a healthy liver to a fatty liver © crevis | AdobeStock
Depending on the extent of fatty liver disease, doctors differentiate between three different degrees of severity:
- Grade 1: mild or mild fatty liver
- Grade 2: moderate fatty liver
- Grade 3: severe fatty liver
A distinction is also made between two different forms of fatty liver disease, depending on the cause:
- alcoholic fatty liver and
- non-alcoholic fatty liver.
Fatty liver is often caused by obesity © Kateryna_Kon | AdobeStock
Fatty liver is particularly common in western industrialized countries. There, fatty liver is one of the most common liver diseases. In Germany, for example, an estimated 20 to 30 percent of the population suffer from non-alcoholic fatty liver disease. In diabetics, the incidence is said to be as high as 50 percent.
Overall, fatty liver is responsible for around 10 to 20 percent of liver cirrhosis and hepatocellular carcinomas(liver cell cancer).
In most cases, the cause of fatty liver in western industrialized countries is too frequent and excessive alcohol consumption and metabolic syndrome. The latter is a combination ofbeing overweight(obesity), type 2 diabetes mellitus and elevated blood lipid levels.
The amount of alcohol at which alcoholic fatty liver disease develops varies from person to person. The critical upper limit is a daily consumption of 10 grams of alcohol for women and 20 grams of alcohol for men. This corresponds to an eighth or a quarter of a liter of wine or one or two glasses of beer (0.3 liters).
Alcohol as the main cause of liver damage such as fatty liver © Henrie | AdobeStock
Other possible causes of fatty liver are other diseases such as
Other possible risk factors for the development of a fatty liver include
- long-term use of liver-damaging medication (such as cortisone, acetylsalicylic acid, tetracyclines, amiodarone, methotrexate),
- poor diet and
- stressful situations for the body (such as prolonged starvation or artificial nutrition).
Unhealthy diet as a risk factor for the development of a fatty liver © happy_lark | AdobeStock
A fatty liver can also occur, particularly in the last few months of pregnancy. However, this is usually harmless. However, patients with an acute fatty liver during pregnancy require clinical care.
In addition to unknown causes, genetic factors (such as variants of the PNPLA3 gene product) also appear to play a role in some cases. They may be responsible for the development of fatty liver and in particular for the progression to liver fibrosis, liver cirrhosis and liver cell cancer.
A liver with only small amounts of fat does not cause any symptoms. With increasing fatty degeneration, the liver becomes larger. The rather uncharacteristic symptoms that can occur with a fatty liver include
Fever and yellowing of the skin (jaundice) are also possible symptoms of fatty liver disease. However, these symptoms usually only occur when the fatty liver turns into fatty liver inflammation (fatty liver hepatitis or steatohepatitis).
Jaundice indicates liver damage such as fatty liver © Daria | AdobeStock
Around 30 percent of patients with fatty liver have signs of fatty liver inflammation. In obese patients with fatty liver, this is even the case in 50 percent.
Complications of fatty liver can include damage to the cardiovascular system, which can manifest itself in vascular calcification, high blood pressure and circulatory disorders. These in turn can lead to serious illnesses.
A fatty liver is usually diagnosed on the basis of
- the patient's medical history (anamnesis),
- a physical examination,
- a blood test and
- an ultrasound examination of the abdomen.
When taking the medical history, the doctor first asks the patient questions about
- the complaints,
- existing illnesses,
- dietary habits and
- alcohol consumption.
During the physical examination, the doctor will palpate the abdomen to determine whether the liver is abnormally enlarged.
Palpation of the right upper abdomen © pressmaster | AdobeStock
The following values are determined as part of the laboratory diagnostic blood test:
- Liver values (gamma-GT, GOT, GPT, alkaline phosphatase)
- Blood lipid values (triglycerides, cholesterol, HDL and LDL cholesterol)
- Other blood values (such as bilirubin, fasting blood sugar or HbA1c)
However, laboratory values alone cannot be used to detect a fatty liver. This is because liver values are not necessarily elevated in patients with a fatty liver, for example. However, certain molecular markers (e.g. M30, M65, adiponectin) can also indicate liver damage.
Evaluation of a laboratory diagnostic blood test © Stockfotos-MG | AdobeStock
An ultrasound examination of the abdomen shows the changes typical of a fatty liver. In some cases, magnetic resonance imaging can provide further helpful information.
If there is a suspicion that liver fibrosis or cirrhosis has already developed, the doctor can perform elastography. This is a diagnostic procedure that can be used to determine the stiffness and possibly the fat content of the liver.
To confirm the diagnosis of fatty liver and determine the causes and extent of the fatty liver, a puncture of the liver (liver biopsy) is necessary. The doctor takes a small tissue sample from the liver under local anesthesia using a special hollow needle. This is then examined under a microscope in the laboratory.
Liver biopsy © SciePro | AdobeStock
A so-called PNPLA3 gene marker can now be used to assess the risk of the fatty liver developing into liver fibrosis, liver cirrhosis and liver cell cancer as the disease progresses.
Specific treatment of the fatty liver itself, for example with medication, is not yet possible.
Rather, the treatment of fatty liver is about counteracting the progression of the disease or reversing the fatty degeneration of the liver. This involves
- to eliminate or reduce the causes of fat accumulation in the liver,
- change lifestyle habits and
- treat the underlying disease.
Depending on the cause of the fatty liver, this usually means that those affected have to give up alcohol and, if they are overweight, change their diet and lose weight. A balanced, low-fat and low-sugar diet with plenty of protein and sufficient exercise is important.
An alcoholic fatty liver can regress with abstinence from alcohol © Pormezz | AdobeStock
Diabetics should also make sure that their blood sugar levels are well controlled. Those affected should also have any existing lipometabolic disorders treated, if necessary by taking lipid or cholesterol-lowering drugs.
Bariatric surgery may be necessary for patients who are severely overweight and for whom conservative weight loss measures have not been successful. Bariatric surgery procedures such as gastric bypass or gastric banding are available for this purpose.
Patients with liver cirrhosis should undergo an ultrasound examination at least every 6 months. The doctor examines the liver for a developing hepatocellular carcinoma.
The prognosis for fatty liver is generally good. Most fatty liver disease can usually be reversed and cured. The prerequisite is that the causes are eliminated as quickly as possible and the underlying diseases are adequately treated.
In principle, a fatty liver can regress within around 2 to 3 months, provided the person affected abstains from alcohol and eats a balanced, low-fat diet.
However,if no countermeasures are taken, a fatty liver can develop into fatty liver inflammation. Under certain circumstances, it can also develop into cirrhosis of the liver and then into hepatocellular carcinoma. These diseases can no longer be reversed. A complete cure is then no longer possible.