fatty liver
Introduction
Introduction to fatty liver Due to factors such as disease or drugs, the accumulation of lipids in liver cells exceeds 5% of liver wet weight, called fatty liver, and the accumulation of lipids in the liver may be triacylglycerol, fatty acid, phospholipid or cholesterol. Ester and the like, among which triacylglycerol is mostly. According to the fat content, fatty liver can be divided into light type (containing 5% to 10% of fat), medium type (containing fat 10% to 25%), heavy (including fat 25% to 50% or >30%), fat The liver is a common clinical phenomenon, not an independent disease, including pathological changes such as steatosis, steatohepatitis and cirrhosis. The clinical manifestations of fatty liver are closely related to its etiology, pathological type and its accompanying disease state. Clinically, fatty liver can be divided into acute and chronic according to the onset of the disease. The former is relatively rare, and the pathology is mostly small. Follicular hepatocyte steatosis, the latter mainly refers to macrophage hepatocyte steatosis caused by obesity, diabetes and alcohol abuse. basic knowledge The proportion of illness: 1.5% Susceptible people: good for middle-aged and older people, more men than women Mode of infection: non-infectious Complications: peripheral neuritis alcoholic hepatitis cirrhosis obesity hyperlipidemia hypertension ascites edema spider mites
Cause
Fatty liver disease
Causes
The etiology of fatty liver includes the conditions of fatty liver (inducing) and the causes of fatty liver (pathogenic factors). In the process of fatty liver development, the immune status of the body, nutritional factors, genetic factors, life The way, as well as age and gender, play a very important role, which is the conditional factor for the onset of fatty liver.
The pathogenic factors of fatty liver include chemical factors, nutritional factors, endocrine and metabolic factors, biological pathogenic factors, and genetic factors.
Chemical factors (20%):
Including chemical poisons (yellow phosphorus, arsenic, lead, benzene, carbon tetrachloride, chloroform, etc.), drugs (methotrexate, tetracycline, amiodarone, glucocorticoids, etc.), alcohol, etc., alcoholism has always been a European and American fat The most common cause of liver and cirrhosis.
Nutritional factors (20%):
Excessive diet and obesity caused by overweight are one of the most common causes of fatty liver in recent years. Protein and calorie deficiency are another important cause of fatty liver. Malnutrition is a chronic nutritional deficiency disease, mainly due to the long-term lack of energy and protein in the human body. According to different reasons, it can be divided into two major categories: primary and secondary.
(1) Primary malnutrition: mainly due to lack of food protein and energy supply or intake, long-term inability to meet the physiological needs of the human body, mostly in developing countries or economically backward areas.
(2) Secondary malnutrition: induced by other diseases, malnutrition in developed countries such as Europe and the United States, as well as in older children and adults, is secondary, often in malabsorption syndrome, chronic infection and inflammation. Chronic wasting diseases such as sexual diseases and malignant tumors, lack of protein in food, and even fatty calories can cause fatty liver. Fatty liver caused by malnutrition is mainly found in many endocrine and metabolic diseases such as hypercortisolism in children, hyperthyroidism, high Uric acidemia, hyperlipoproteinemia, and hyperlipidemia of diabetes can cause hepatic steatosis, and non-insulin-dependent diabetes is most closely related to fatty liver.
Biological factors (20%):
Including pathogenic microorganisms and parasites such as viruses and bacteria, these pathogenic factors mainly cause degeneration and necrosis of hepatocytes and inflammatory cell infiltration. Recently, some hepatitis C virus and hepatitis D virus infection can cause macrobubble and vesicles, respectively. Hepatic steatosis, tuberculosis, sepsis and other chronic bacterial infections can also cause hepatic steatosis due to factors such as malnutrition, hypoxia and cytotoxic damage. In addition, various viral hepatitis recovery periods and chronic viral infections It can induce obese fatty liver.
Genetic factors (10%):
It is mainly caused by mutations in genetic material genes or aberrations of chromosomes. In the liver, they mainly cause congenital metabolic liver disease, including Wilson's disease, galactosemia, glycogen accumulation disease, and fructose intolerance. Hereditary diseases can cause macrophage fatty liver, and congenital defects of urea circulating enzymes, genetic defects of mitochondrial fatty acid oxidation can cause vesicular fatty liver, and in some families, people have the qualities of certain diseases, such as Obesity, type I diabetes, primary hyperlipidemia, etc., this phenomenon is called genetic susceptibility.
Pathogenesis
The fat in the food is enzymatically hydrolyzed and combined with bile salts, absorbed by the intestinal mucosa, and then forms chylomicrons with proteins, cholesterol and phospholipids. After the chylomicrons enter the liver, the sinusoidal cells are decomposed into glycerol and fatty acid, and the fatty acid enters. After hepatocytes, they are oxidized in the mitochondria, decomposed to release energy, or esterified to synthesize triacylglycerol, or converted into phospholipids and cholesterol esters in the endoplasmic reticulum, and most of the triacylglycerols and apolipoproteins in the liver cells are formed. Very low-density lipoprotein (VLDL) enters the blood circulation in this form. VLDL is delipidated in the blood to provide fatty acid to various tissues. Lipid metabolism is the cause of fatty liver:
(1) Excessive fat in food, hyperlipidemia and increased mobilization of adipose tissue (hunger, trauma and diabetes), free fatty acid (FFA) transport into the liver, providing a large number of precursors for triglyceride synthesis in the liver.
(2) The lack of essential fatty acids in food, acute alcoholism, acute threonine deficiency, and high doses of barbiturate salt increase the synthesis of triacylglycerol and free fatty acid in liver cells.
(3) The caloric intake is too high, and the conversion from sugar to triacylglycerol is increased.
(4) Reduced free fatty acid clearance in hepatocytes, excessive drinking, choline deficiency, carbon tetrachloride and ethionine poisoning can inhibit the oxidation of free fatty acid in the liver, ethionine poisoning and choline deficiency It can block phospholipid synthesis.
(5) One or more links such as VLDL synthesis or secretion disorder, destroying the dynamic balance of fat metabolism between adipose tissue cells, blood and liver cells, causing a loss of balance between the synthesis and secretion of triglyceride in hepatocytes, ultimately leading to Fat-based lipids overexpose in hepatocytes to form a fat.
Prevention
Fatty liver prevention
1, a reasonable diet, daily meals for three meals to be reasonable, for the thickness of the mix, nutritional balance, a sufficient amount of protein can remove liver fat.
2, appropriate exercise, daily physical exercise, depending on your physical fitness to choose appropriate sports, such as jogging, playing table tennis, badminton and other sports; to start from a small amount of exercise, step by step, and gradually reach the appropriate amount of exercise to enhance the body's fat consumption .
3, the use of drugs with caution, the liver is the chemical plant of the human body, any drug into the body must be detoxified by the liver, so usually do not take medicine, especially do not casually advertise the so-called health-care drugs, there are symptoms Patients with fatty liver should be more cautious when choosing drugs. Beware of the side effects of drugs, especially drugs that are harmful to the liver, should not be used to avoid further aggravation of liver damage.
4, In addition, the mood should be cheerful, not angry, less angry, pay attention to work and rest, etc. is also very important.
Complication
Fatty liver complications Complications peripheral neuritis alcoholic hepatitis cirrhosis obesity hyperlipidemia hypertensive ascites edema spider mites
Fatty liver can be an independent disease or a concurrent manifestation of certain systemic diseases.
1, often accompanied by other manifestations of alcoholism, such as alcohol dependence, pancreatitis, peripheral neuritis, anemia, glossitis, alcoholic hepatitis, cirrhosis and so on.
2, over-nutrition fatty liver often management other basic diseases occur, such as obesity, diabetes, hyperlipidemia, hypertension, coronary atherosclerotic heart disease (referred to as coronary heart disease), gout, cholelithiasis and so on.
3, malnutrition fatty liver often coexist with chronic wasting diseases, such as tuberculosis, ulcerative colitis.
4, acute fatty liver in pregnancy often complicated by renal failure, hypoglycemia, pancreatitis, sepsis, disseminated intravascular coagulation (DIC).
5, severe fatty liver patients can have ascites and lower extremity edema, other can also have spider mites, male breast development, testicular atrophy, impotence, women have amenorrhea, infertility and so on.
Symptom
Fatty liver symptoms Common symptoms Liver enlargement Spider Fatigue jaundice fatigue fatigue Hepatic cell fatty sputum ascites Liver mild steatosis liver palm
The clinical manifestations of fatty liver are closely related to its etiology, pathological type and its accompanying disease state. Clinically, fatty liver can be divided into acute and chronic according to the onset of the disease. The former is relatively rare, and the pathology is mostly small. Follicular hepatocyte steatosis, the latter mainly refers to macrophage hepatocyte steatosis caused by obesity, diabetes and alcohol abuse.
Acute vesicular fatty liver
Acute vesicular fatty liver clinical manifestations similar to acute or subacute severe viral hepatitis, often fatigue, nausea, vomiting and varying degrees of jaundice, and even the emergence of disturbances of consciousness and epilepsy, severe cases of rapid occurrence of hepatic encephalopathy in the short term, ascites Renal failure and disseminated intravascular coagulation (DIC) can eventually die of cerebral edema and cerebral palsy. Of course, some patients with acute vesicular fatty liver have mild clinical manifestations, only transient vomiting and liver function. The performance of the lesion, liver biopsy suggests vesicular steatosis, but inflammatory cell infiltration and necrosis is not obvious, mitochondrial abnormalities can be seen by electron microscopy.
2. Chronic bullous fatty liver
Chronic bullous fatty liver is usually the fatty liver, which occurs in middle-aged and elderly people. Men may be more than women. The onset is concealed. Generally, it is benign. The symptoms are mild and non-specific, even if steatohepatitis has occurred. Liver cirrhosis, sometimes liver disease-related symptoms can still be absent, so it is occasionally found in the assessment of other diseases or health checkups for liver function and imaging examination.
Liver enlargement is a common sign of fatty liver, the incidence can be as high as 75% or more, mostly mild to moderate hepatic enlargement, smooth surface, rounded edges, normal or slightly hard texture without obvious tenderness, chronic liver disease such as portal hypertension The signs are relatively rare, and the detection rate of splenomegaly is generally less than 25% in cases of steatohepatitis. The focal fatty liver is less obvious because of the small lesion range, but it is not the case when other liver diseases coexist.
(1) Symptoms: Mild fatty liver can be free of any clinical symptoms, especially in the elderly due to excessive diet or high-fat diet, clinically known as "hidden fatty liver", moderate or severe patients, especially longer duration Symptoms are more obvious. Common symptoms are symptoms such as fatigue, loss of appetite, right season hypochondriac pain, nausea, abdominal distension and other symptoms of liver dysfunction, may be associated with abdominal pain, mainly right upper abdominal pain, occasional upper abdominal pain, with tenderness, In severe cases, there is rebound tenderness, fever, increased white blood cell count, and the performance of acute abdomen. It needs to be treated in time. This kind of performance is rare. During the operation, the liver capsule is stretched and the liver ligament is involved. The patient's pain is caused by the liver capsule. Due to stretching, hepatic ligaments are pulled, fat cysts are ruptured and inflamed, severe fatty liver can be combined with portal hypertension and gastrointestinal bleeding, and vitamin deficiency can also be accompanied by anemia, glossitis, peripheral neuritis and nervous system Symptoms, there may be ascites and lower extremity edema, others may also have spider mites, male breast development, testicular atrophy, impotence, women with amenorrhea, infertility and so on.
(2) Signs: 64% of those who are overweight and obese, and 15% of liver enlargement, may have tenderness in the liver area, splenomegaly, and spider mites and liver palms on the skin.
Examine
Fatty liver examination
Laboratory inspection
1. Serum enzymatic examination:
(1) ALT, AST: generally mildly elevated, reaching 2 to 3 times the upper limit of normal, AST elevation of alcoholic fatty liver is obvious, AST/ALT>2 has diagnostic significance, ALT is not alcoholic fatty liver /AST>1, ALT>130U, suggesting that liver lobular fat infiltration is obvious, and persistently elevated ALT suggests fatty granuloma.
(2) -GT, ALP: -GT elevation is more common in alcoholic fatty liver, ALP is also seen to increase, up to 2 times the upper limit of normal, -GT can be elevated in patients with nonalcoholic fatty liver.
(3) GST: can reflect stress liver damage, more sensitive than ALT.
(4) glutamate dehydrogenase (GDH), ornithine carbamoyltransferase (DCT), GDH is a mitochondrial enzyme, mainly active in the liver acinar III, DCT is urea synthase, involved in methylation In response to fatty liver, both enzymes are elevated, especially alcoholic fatty liver, with a GDH/OCT > 0.6.
(5) cholinesterase (CHE), lecithin cholesterol acyltransferase (LCAT): 80% fatty liver serum CHE and LCAH increased, but low nutritional status of alcoholic fatty liver is not obvious, CHE identifies obesity Sexual fatty liver has a certain meaning.
2. Plasma protein changes:
(1) -globulin, 1, 2, lipoprotein increased.
(2) Albumin is normal.
(3) In obese fatty liver, LDL-C increased, HDL-C decreased significantly, and Apo B, Apo E, Apo CII and III increased.
3. Plasma lipids TG, FA, cholesterol, and phospholipids are often elevated, and cholesterol is significantly elevated, often >13mmol/L.
4. Pigment excretion test BSP, ICG excretion is reduced, in obesity and alcoholic fatty liver, because fat accumulation is mostly in the liver acinar III band, and pigment treatment is also in this part, liver fat storage affects hepatocyte excretion The function of the pigment, the degree of excretion reduction is related to the degree of liver fat infiltration.
5. Bilirubin may have elevated blood bilirubin in severe fatty liver, and mild to moderate fatty liver bilirubin is normal.
6. Prothrombin time (PT) Non-alcoholic fatty liver is more normal and partially prolonged.
7. The blood insulin level showed a high response delay type, and the glucose tolerance curve peaked and the decline was delayed.
8. Blood urea nitrogen, uric acid occasionally increased.
Auxiliary inspection
1.B ultra-examination: The ultrasound image of diffuse fatty liver is mainly expressed as echo attenuation. According to the degree of attenuation, fatty liver can be divided into three types:
(1) Mild fatty liver: manifested as near-field echo enhancement, far-field echo attenuation is not obvious, and the intrahepatic tubular structure is still visible.
(2) Moderate fatty liver: the front field echo is enhanced, the back field echo is attenuated, and the tubular structure is blurred.
(3) Severe fatty liver: The near-field echo is significantly enhanced, the far-field echo is obviously attenuated, the tubular structure is unclear, and it is unrecognizable. The sensitivity of ultrasound to severe fatty liver is 95%.
2. CT examination: The CT image of fatty liver is different from the real-time ultrasound (US) image. The accuracy of CT diagnosis is better than that of B-ultrasound. The main manifestation is that the liver density is generally or limited, even lower than the spleen and intrahepatic vascular density. In contrast, echo in the portal vein is enhanced, and the density is reduced in accordance with the severity of fatification. Dynamic CT changes can reflect the increase and decrease of intrahepatic fat infiltration. Diffuse fatty liver is generally lower in liver density on CT. Spleen and intrahepatic vascular density, severe fatty liver, liver CT value can be reduced to about 10Hu (normal liver density is 6 ~ 12Hu higher than the spleen), enhanced CT scan, fatty liver liver vascular shadow is very clear, Its shape, no abnormality in the direction, sometimes the blood vessels can be fine and narrow, but there is no change, the phenomenon of wrapping, help to identify the focal non-affected area of liver cancer and fatty liver (normal "liver island").
3. MRI examination: its value is generally considered to be smaller than US and CT. Magnetic resonance imaging (MRI) of fatty liver is characterized by whole liver, one leaf or focal fat infiltration, spin echo (SE) sequence and reverse recovery (IR). The T1 weighted signal of the pulsating sequence is normal. The short IR sequence and the T2-weighted image signal of SE can be slightly higher, but only the proton image of fat, the high signal of fat infiltration area, the normal position of blood vessels in the liver, and the MRI measurement in recent years. Liver tissue fat content.
4. Liver biopsy: an important method for the diagnosis of fatty liver, especially for localized fatty liver. The biopsy of liver tissue guided by B-ultrasound is far more accurate and safe than the blind liver puncture method in the past. The significance of biopsy is to determine whether there is liver. Fat infiltration, with or without fibrosis and exclusion of space-occupying lesions that are difficult to identify in non-invasive examinations, also have guiding value for the choice of treatment options, indications for fatty liver biopsy:
(1) Focal fatty liver or diffuse fatty liver with normal liver island is difficult to distinguish from malignant tumors, and liver biopsy should be performed under the guidance of B-ultrasound.
(2) to identify the causes of some rare fatty liver diseases, such as cholesterol ester storage disease, glycogen accumulation disease, Wilson disease and so on.
(3) Asymptomatic suspicious nonalcoholic steatohepatitis, liver biopsy is the only means of diagnosis.
(4) Alcohol-absorptive and alcoholic liver disease or alcoholic liver disease have unexplained clinical or biochemical abnormalities, and alcoholic hepatitis requires liver biopsy to exclude active infection before corticosteroid treatment.
(5) After obesity-induced fatty liver patients reduce their original body weight by 10%, liver function enzymes continue to be abnormal, requiring liver biopsy to find other causes.
(6) Suspected of severe hepatitis caused by fatty liver, requiring liver biopsy to clearly diagnose and understand the cause.
(7) To evaluate the reliability of certain serological indicators, B-ultrasound, CT and other imaging examinations for the diagnosis of fatty liver and fibrosis, liver biopsy changes should be used as the gold standard, and objectively evaluate a certain treatment plan for fatty liver. The exact effect of fibrosis treatment.
(8) Anyone who is suspected to be not a simple hepatocyte steatosis or suspected of multiple causes of fatty liver or liver dysfunction needs to be identified by liver biopsy to determine its specific cause or cause of illness.
Diagnosis
Fatty liver diagnosis
diagnosis
The diagnosis of fatty liver mainly depends on medical history, clinical manifestations and laboratory tests, especially B-ultrasound and CT have certain characteristics, and the diagnosis depends on liver biopsy.
1. History: Alcoholic fatty liver has a long history of alcohol abuse, especially white wine with high alcohol content. In addition, there are obesity, diabetes, high-energy venous nutrition, use of related drugs and exposure to poisons.
2. Clinical manifestations: After the formation of fatty liver, most of them show loss of appetite, nausea, vomiting, weight loss, fatigue, abdominal distension, liver discomfort or dull pain.
3. Physical examination: can touch the swollen liver (usually within 2-3 cm below the right rib), the surface is smooth, the edge is round and blunt, the texture is soft or medium hardness, there may be mild tenderness, some patients have sputum pain, Severe patients may have cirrhosis.
4. Laboratory and other auxiliary examinations: alanine aminotransferase (ALT) is elevated, and mild jaundice may occur in a small number of patients.
Differential diagnosis
Should be differentiated from other common liver diseases such as viral hepatitis, autoimmune hepatitis, metabolic liver disease, cirrhosis, etc., for focal fatty liver, need to be associated with primary or secondary liver cancer, hepatic hemangioma and other space-occupying lesions Identification.
First, severe fatty liver
Severe fatty liver refers to fatty liver with poor clinical symptoms and poor prognosis. Strictly speaking, it is a pathological process of certain critical diseases, including acute fatty liver of pregnancy, fatty liver syndrome of encephalopathy, and it is associated with general fatty liver. Clinical symptoms, signs, and disease prognosis are significantly different.
(1) Acute fatty liver in pregnancy
This disease, also known as obstetric acute yellow liver atrophy, is a serious complication of pregnancy, clinically rare, poor prognosis, the disease occurs in the third trimester of pregnancy (30-40 weeks), it is believed that a large number of oral administration during pregnancy With the infusion of tetracycline, it is possible to induce the disease.
The main clinical symptoms: sudden onset of nausea, vomiting, and even hematemesis, accompanied by upper abdominal pain, jaundice in a week, often no itching, after the jaundice rapidly deepened, followed by varying degrees of disturbance of consciousness or coma; serum bilirubin Mild to moderate increase, such as DIC, vomiting brown liquid or blood, as well as hematuria, blood in the stool, purpura, gums and injection site bleeding, while platelet and fibrinogen decreased, FDP value increased and prothrombin time extended, Half of patients with oliguria, metabolic acidosis and other early renal failure.
(B) encephalopathy fatty liver syndrome (Reye syndrome)
The disease mainly occurs in children and adolescents. There is always a certain kind of virus infection, cold-like prodromal symptoms and chickenpox before the onset of symptoms. After 2-3 days of improvement, the symptoms of vomiting suddenly appear frequently, accompanied by severe headaches, and enter the sputum within a few hours. Stupor and cerebral cortex, and finally into a coma, often accompanied by fever, hypoglycemia, abnormal liver function, the disease is dangerous, high mortality.
Second, liver cancer, hepatic hemangioma, liver abscess, hepatic cyst
Localized fatty liver changes need to be differentiated from them. Liver cancer, especially small cell liver cancer and alpha-fetoprotein-negative liver cancer, is difficult to distinguish from localized fatty liver. Usually, small cell liver cancer is mostly attenuated, often with envelope shadow. And portal vein invasion, metastatic liver cancer is mostly ultrasound-enhanced, common multi-nodule, no portal system invasion, CT shows that liver cancer is more densely defined in the boundary area, contrast tissue is enhanced after contrast agent is added, selective hepatic artery Contrast can better display tumor blood vessels or hemangioma. Although hepatic angiography has difficulties in identifying hepatic hemangioma and liver cancer, it still has some value for excluding liver abscess and hepatic cyst. B-ultrasound guided liver biopsy is confirmed. An effective method for various intrahepatic space-occupying lesions.
Third, viral hepatitis
Fatty liver patients with diffuse distribution of intrahepatic steatosis, often need to be differentiated from viral hepatitis, viral hepatitis patients in addition to fatigue, anorexia, fever, nausea, vomiting, jaundice, urine yellow and other performance, epidemiology, Etiological examinations help to confirm the diagnosis.
