What are the main functions of the liver?
The liver has complex physiological functions.
(1) Metabolic functions.
(1) Protein metabolism. The liver is the only albumin-producing organ in the body. The synthesis, maintenance and regulation of globulin, plasma albumin, fibrinogen and prothrombin all require the participation of the liver. Amino acid metabolism such as the deamidation reaction, urea synthesis and ammonia processing.
②Glucose metabolism. After digestion of dietary starch and sugar into glucose absorbed through the intestine, the liver synthesizes it into hepatic glycogen for storage in the liver, which can then be broken down into glucose for use by the body when it needs it. When the blood glucose concentration changes, the liver has a regulatory role. Therefore, under normal conditions, the synthesis and breakdown of hepatic glycogen often maintain a dynamic balance.
(iii) Fat metabolism. The synthesis and release of neutral fats, fatty acid catabolism, ketone body production and oxidation, cholesterol and phospholipid synthesis, lipoprotein synthesis and transport all take place in the liver.
④Vitamin metabolism. The synthesis and storage of many vitamins, such as A, B, C, D and K, are closely related to the liver. When the liver is significantly damaged, vitamin A deficiency can occur secondary to night blindness or dry skin syndrome.
⑤ Hormone metabolism. The liver is involved in the inactivation of hormones. Sex hormone dysregulation may occur when liver function is chronically impaired, and may include loss of libido, scarcity or loss of axillary and pubic hair, impotence, testicular atrophy, gynecomastia, menstrual irregularities, and the appearance of liver palms and spider nevi.
(vi) Others. The liver participates in the process of water metabolism through the action of nerves and body fluids and counteracts the action of antidiuretic hormone in the posterior pituitary gland to maintain normal urine output. The liver also has the role of regulating acid-base balance and mineral metabolism, and is an important heat supply organ.
(2) Secretion and excretion of bile: The liver produces about one liter of bile in 24 hours, which is transported to the gallbladder via the bile ducts. The gallbladder plays the function of concentrating and discharging bile to facilitate the digestion and absorption of fat in the small intestine.
(3) Detoxification function: foreign or metabolically produced toxic substances in the body are detoxified in the liver and turned into non-toxic or highly soluble substances, which are excreted from the body with bile or urine.
(4) Functions related to blood: The liver is the main hematopoietic organ in the fetus and is replaced by the bone marrow in the adult, and hematopoietic functions cease, but its hematopoietic functions are restored in certain pathological conditions. In addition, almost all coagulation factors are produced by the liver. The liver plays an important regulatory role in the dynamic balance of the two systems of coagulation and anticoagulation in the body. Therefore the severity of liver function disruption often parallels the degree of coagulation disorder, and those with liver failure often have severe bleeding.
What is a liver function test? What are the broad liver function tests?
When it comes to liver function, people immediately think of transaminases, and some people even think that transaminases are liver function, but in fact, there are many types of liver function, and there are more than 700 types of tests reflecting liver function, and new tests are still being developed and established, including four main categories.
① Tests reflecting liver cell damage: including serum enzymes and serum iron, etc. Serum enzyme tests are commonly used, such as alanine aminotransferase (ALT), glutamate aminotransferase (AST), alkaline phosphatase (ACP), γ-glutamyl transpeptidase (γ-GT), etc.
② Tests reflecting the excretory function of the liver: detecting the ability of the liver to excrete and clear certain endogenous (bilirubin, bile acids, etc.) or exogenous (dyes, drugs, etc.) high uptake, the clinical detection of bilirubin quantitative commonly used, total bilirubin greater than 17.1 μmd / L for jaundice cases, if the bilirubin progressive rise and accompanied by a decline in ALT, called enzyme bile separation, suggesting aggravation of the disease, with the possibility of turning into severe hepatitis If the bilirubin rises progressively and ALT decreases, it is called enzyme bile separation, which indicates aggravation of the disease and the possibility of turning into severe hepatitis.
ALb and PT are routine tests that reflect the reserve capacity of the liver by detecting the synthesis function of the liver, and a decrease in ALb indicates a decrease in protein synthesis, while a prolongation of PT indicates a decrease in the synthesis capacity of various coagulation factors.
④ Tests reflecting interstitial changes in the liver: serum protein electrophoresis has largely replaced the flocculent reaction, and the degree of increase in γ-globulin can evaluate the evolution and prognosis of chronic liver disease, suggesting hypocellularity and inability to remove endogenous or enteric antigenic substances from the blood circulation. In addition, serum levels of hyaluronic acid, laminin, type III procollagen peptide and type IV collagen reflect changes in hepatic endothelial cells, lipid storage cells and fibroblasts, which are closely associated with liver fibrosis and cirrhosis.
What are the liver function tests commonly prescribed by doctors?
1.Glutamic acid aminotransferase (ALT, GPT)
2.Glutamic-oxalacetic aminotransferase (AST, GOT)
3.Gamma-glutamyl transpeptidase (GGT)
4.Alkaline phosphatase (ALP, AKP)
5.Total bile acid (TBA)
6.Total protein (TP), albumin (Alb, A), globulin (Glb, G)
7, total bilirubin (TBil), direct bilirubin (DBil), indirect bilirubin (IBil).
Don’t look at so many data related to the liver, their up and down fluctuations have their own significance, the main clinical significance are.
Items 1-4 are the main enzyme tests. When liver cells are necrotic, various enzymes in the liver cells are released into the blood, resulting in an increase in enzyme indicators.
1. ALT: It is one of the most sensitive indicators of hepatocyte damage and is mainly distributed within hepatocytes. Mild to moderate increase is seen in fatty liver, chronic hepatitis, cirrhosis, liver cancer, schistosomiasis, heart disease, gallbladder disease, after the use of certain drugs, chemical poisoning, etc. Significant increase is seen in acute viral hepatitis, acute toxic hepatitis, etc.
2, AST: mainly distributed in tissue cells, most in cardiac muscle cells, followed by liver cells. The increase is seen in acute myocardial infarction, trauma, liver cancer, after intense exercise, after the use of certain drugs, etc. In particular, we should pay attention to the change of ALT/AST ratio, >1 indicates acute hepatitis and chronic hepatitis light; <1 indicates cirrhosis, liver cancer, severe hepatitis, liver necrosis, myocardial infarction; if <3 is usually primary liver cancer.
3.GGT: Widely distributed in hepatocyte capillary bile duct and bile duct system. Mild increase is seen in acute and chronic pancreatitis, gallbladder disease, moderate increase is seen in acute and chronic viral hepatitis, alcoholic hepatitis, liver cancer, significant increase is seen in pancreatic cancer, etc. Obstructive jaundice is significantly elevated in patients.
4. ALP: Most of it comes from the liver, bones, small intestine, kidneys, etc. Increased seen in obstructive jaundice, jaundice hepatitis, cirrhosis, rickets, after the use of certain drugs, significantly increased > 500 U / L, should be alert to malignant lesions.
5.TBA: It is produced by the breakdown of cholesterol in the liver. The increase is seen in acute and chronic hepatitis, liver cirrhosis, liver cancer, etc. It has high value for the diagnosis of chronic hepatitis, especially cirrhosis.
6, TP, AlB, GlB, A/G: The degree of albumin reduction parallels the severity of hepatitis. In patients with chronic and severe hepatitis and cirrhosis, albumin concentration decreases while globulin production increases, and A/G is the ratio of albumin to globulin, which is normally 1.5-2.5. Therefore, when liver function is impaired, there can be a decrease in total protein and a decrease or even an inversion of the A/G ratio.
7, TBil, Dbil, IBil: used to determine the type of jaundice and the degree of jaundice.
Through the above understanding, we know the importance and complexity of liver function tests. If there is an abnormality in the test, it should be analyzed together with the medical history, and should not be taken lightly!
What are the common causes of abnormal liver function?
Common causes of liver function abnormalities in Chinese include viral hepatitis, fatty liver and gallstone disease, but alcohol consumption, fatigue, drugs and colds also often cause liver function abnormalities.
When do I need to check my liver function?
1.Regular liver function tests are recommended for all patients who may have the above-mentioned etiology.
2.Patients with one of the following symptoms: unexplained jaundice, weakness, poor appetite, aversion to oil, abdominal distension, epigastric pain, fever, wasting, etc.
What should I pay attention to before doing liver function test?
This is because normal human blood contains a certain amount of large molecules of β and γ globulin, which can precipitate by combining with certain chemical reagents, while small molecules of albumin and α1- globulin can prevent precipitation. Therefore, in normal human serum, no precipitation or slight precipitation occurs due to the inhibitory effect of albumin after the addition of the prescribed chemical reagents. In hepatitis patients, due to the decrease of albumin and increase of β and γ globulins in the serum, significant precipitation occurs after the addition of chemical reagents in their serum. The composition of the serum is changed after eating, and precipitation of varying degrees occurs even in normal human serum after the addition of chemical reagents. The precipitation occurs more significantly when high protein or high fat foods are consumed. The reported results can easily lead doctors to misdiagnose a normal person as a hepatitis patient. In order to make the results more accurate, it is required that a fasting blood sample be taken for all liver function tests.
This test has now been replaced by more advanced methods, and even non-fasting blood samples can be used to check liver function values, which can also be used in emergency situations. However, the normal values of liver function are obtained from the fasting blood of a normal person and processed statistically. Since the digestion and absorption activities of the stomach and intestines are basically completed after meals, the various biochemical components in the blood are more stable, and the values measured at this time can reflect the biochemical changes of the body more truly and help in the diagnosis of diseases. Otherwise, if the blood is collected after eating, the test results cannot be judged because of the influence of food. Therefore, in non-exceptional cases, it is recommended to take blood on an empty stomach as much as possible.
How to evaluate and choose the gong liver energy test?
I. Liver synthesis function
(i) Albumin (Alb)
The liver is the only place where albumin is synthesized, and serum albumin level is one of the good indicators of chronic liver injury. Decreased serum albumin level is seen in: insufficient nutritional intake, impaired synthesis, excessive consumption and increased loss. The serum albumin level in patients with chronic liver disease can reflect the ability of the liver to synthesize albumin and changes in the volumetric distribution of albumin, and if the serum albumin level is reduced and not easily recovered, the prognosis is often poor.
(ii) Prothrombin time
In hepatic impairment, the associated impaired synthesis of coagulation factors can lead to prolonged PT, which is one of the early predictors of abnormal liver function. prolonged PT and uncorrectable vitamin K predicts extremely poor liver function. In fulminant liver failure, PT is an important early diagnostic indicator.
(iii) Lipids and lipoproteins
Lipids and lipoproteins are not sensitive indicators of liver damage, but serum cholesterol ester levels decrease in response to hepatocellular damage and are proportional to the degree of liver damage. In chronic liver disease, lipoproteins are reduced and their levels are negatively correlated with transaminases and bilirubin.
Excretory function of the liver
(A) Bilirubin
The normal level of total bilirubin TBIL is <1.1mg/dl (17.1μmol/l), 70% of which is indirect bilirubin and cannot be filtered from the kidney. Only direct bilirubin can be excreted from the urine. Caution.
1, TBIL < 5 times normal (85 μmol/l) in hemolytic jaundice when liver function is normal.
2, TBIL < 500 μmol/l in jaundice of any cause when renal function is normal.
3, There is jaundice, but the urine bilirubin is negative, indicating elevated indirect bilirubin.
4, Many jaundices that are purely based on elevated indirect bilirubin are Gilbert syndrome, this syndrome has no pathological tissue changes in liver tissue, no significant effect on the organism, and generally no special treatment is needed.
III. Serum enzymatic levels
(I) ALT, AST
The specificity of ALT is better than AST.
1, when ALT > 10 times normal, liver damage is more certain (such as chronic hepatitis B)
2, ALT and AST are elevated in biliary tract diseases, but < 8 times normal
3.The ratio of AST/ALT.
(1) estimate the degree of liver damage: the greater, the more serious the damage.
(2) Identify liver disease: alcoholic liver > 2, slow hepatitis B > 1 may have liver fibrosis or cirrhosis.
(B) Alkaline phosphatase ALP
1, ALP>4 times normal: cholestasis syndrome.
2, ALP>2.5 times normal, ALT, AST<8 times normal: 90% cholestasis.
3.ALP>2.5 times normal, ALT, AST>8 times normal: 90% for viral hepatitis.
(C) Glutamyl transpeptidase GGT
90% of patients with hepatobiliary disease have elevated GGT, GGT>10 times normal, mostly seen in alcoholic liver, intrahepatic and extrahepatic biliary sludge, primary liver cancer.
What is the significance of elevated bile acids?
Bile acid is an important component of bile, and the functions of bile acid.
1.Promote the digestion and absorption of lipids.
2.Inhibit the precipitation of cholesterol in the bile (stones).
Bile acid measurement is clinically important for the diagnosis of the following diseases
1.hepatobiliary diseases.
2.Gastrointestinal diseases
3, other diseases that cause changes in bile acid metabolism
Since a variety of diseases may affect the level of bile acids, in clinical practice, bile acids are often used together with other liver function tests as information for the clinician to determine the condition.
How often is it reasonable to review liver function in chronic liver disease?
In the case of active chronic liver disease, one should be instructed by the physician to recheck daily if necessary.
If the chronic liver disease is stable and the patient is not experiencing any discomfort, the interval can be stretched to 1 month to 1 year. A specialist should be consulted for details.
What other tests are needed for patients found to have abnormal liver function
In addition to the routine liver function tests mentioned above, doctors will prescribe other tests depending on the patient’s condition. Common tests include: routine blood, electrolytes, kidney function, urine routine, stool routine; protein electrophoresis, blood sedimentation, C-reactive protein; immune index; tumor index; liver ultrasound, CT or MRI, etc.
Does elevated transaminases necessarily mean hepatitis?
Many people mistakenly believe that abnormal liver function is hepatitis B. Some organizations may even reject new employees because of abnormal transaminases in their physical examination. In fact, this is very incorrect. A survey of a large sample of healthy people in the UK found that 6% of asymptomatic normal people had elevated ALT and AST and 5% of normal people had all tests outside the “normal” range.
Therefore, just one abnormal liver test result may not confirm the diagnosis of liver disease. Therefore, the treatment for a single elevated transaminase level is to review the test at intervals, and if the elevation is more than twice normal, further testing is required.
Can abnormal liver enzymes recover on their own?
The answer is that some causes of liver enzyme abnormalities can recover on their own. For example, short-term viral infections, drug-induced hepatitis, heavy alcohol consumption, fatigue, etc., can be completely self-healing after correcting the cause and do not necessarily require medication.
However, regardless of the cause, if the liver enzyme abnormality exceeds more than two times the normal value, further consultation or observation should be done under the guidance of a doctor.
How do I understand the relationship between type IV collagen and liver fibrosis?
Type IV collagen is a collagen that is the main component of the basement membrane. Collagen accounts for about 5% to 10% of the total protein in the liver. When fibrosis occurs in the liver, the basement membrane is damaged and collagen can increase by about 50%. During the process of collagen proliferation, type IV collagen is deposited in large amounts. Therefore, the measurement of serum type IV collagen can be used as a better diagnostic indicator of cirrhosis.
Is a person with abnormal liver function infectious? Can I go to work?
If the cause of the disease is not viral hepatitis, it is not contagious at all.
Even if it is viral hepatitis, it will definitely be contagious when the disease has recovered or when the virus is not actively replicating.
If the transaminases are not more than twice the normal value, you should be able to work and study normally, but you should avoid overexertion.
How should patients with mild liver function abnormalities take care of their lives?
Combine work and rest, stop smoking and drinking, and have balanced nutrition.
Avoid intake of excessive or unknown ingredients of drugs or health care products.
”What are the five tests of hepatitis B and what do they mean?
The five hepatitis B tests include: HBsAg HBsAb HBeAg HBeAb HBcAb
Hepatitis B two pairs of half results and clinical significance
HBsAg HBsAb HBeAg HBeAb HBcAb Clinical significance
1 + – – – + (major triple positive) acute and chronic hepatitis, HBV replication stage
2 + – – – + Acute HBV infection, chronic HBsAg carriers, weakly infectious
3 + – – – + + Acute HBV tends to recover, chronic HBsAg, long term persistent susceptible to cancer (small triplet)
4 – – – – – No previous HBV infection
5 – + – – + Pre-existing infection with immunity Atypical recovery, acute HBV infection
6 – – – + + Previous HBV infection, acute HBV recovery, few still infectious
7 – – – – + Pre-existing HBV infection, acute HBV window
8 – + – – – Passive or active HBV immunization, recovered from infection
9 – + – + + – Previous HBV infection, acute HBV recovery
10 + – – – – Chronic HBV carrier, acute HBV infection
11 + – – + – Chronic carrier, acute HBV infection tending to recover
12 + – + – – Early infection, highly infectious
13 + – + + + + Acute HBV infection tending to recover, chronic HBsAg carrier
14 + + – – – -/+ Early stage of subclinical HBV infection, secondary infection with different subtypes of HBV
15 + + + – + + Subclinical or atypical infection
What is the meaning of “HBV-DNA” and when should it be checked?
HBV DNA is the deoxyribonucleic acid, any living creature in the world relies on its own DNA to replicate its offspring, so does the hepatitis B virus. HBV DNA invades human liver cells and controls the entire process from replication, equipment to release of the virus. The high replication of HBV DNA means that the disease may be less stable and more contagious. The HBV DNA test also has a monitoring significance, there are generally two types of HBV DNA tests, one is a qualitative test, which is positive or negative, and then the viral load of the virus in the body, the level of viral load determines the level of viral replication, that is, the level of virus concentration in the body. A high viral load may be more infectious and cause a greater likelihood of fluctuations in liver function. Testing for hepatitis B virus DNA is critical for subsequent antiviral therapy and for determining prognosis. In some patients with hepatitis B, the virus can only be detected by hepatitis B virus DNA due to mutations in the hepatitis B virus.
Why do patients with autoimmune liver disease have abnormal liver function?
Autoimmune liver disease is a group of diseases in which the body’s autoimmune response causes excessive liver tissue damage and liver function abnormalities and corresponding signs and symptoms, including autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Autoimmune liver disease usually occurs in women (70%), aged 15 to 40 years. Many patients present with jaundice, fever and abnormal liver function resembling acute hepatitis. Patients usually have evidence of moderate to severe hepatitis with elevated serum ALT and AST with normal or mildly elevated AKP and gamma-GT. Other patients occasionally present with arthralgia, myalgia, polyplasmosis, and thrombocytopenia. Some patients present with mild liver function abnormalities and laboratory abnormalities. Others present with severe liver function abnormalities. Patients with liver disease without risk factors for changes in alcohol, drugs, or viral pathogenesis should especially be considered to have autoimmune liver disease. Since some patients with autoimmune liver disease have twice the normal serum gammaglobulin and have anti-nuclear and/or anti-smooth muscle (anti-actin) antibodies. Another group of patients may have normal or mildly elevated serum gammaglobulins but may have antibodies against specific cytochrome P450 isozymes, called LKM (liver and kidney microsomal) antibodies. Therefore, the diagnosis can be made by serum protein electrophoresis and autoantibody testing.