Introduction to liver function

The liver is not a stranger to us, especially if we are frequent drinkers. In fact, we need to be more familiar with liver function so that we can better prevent and treat physical diseases of the liver.

Introduction to liver function

There are two levels of liver function. One level refers to the physiological functions of the liver, i.e. the liver has the functions of detoxification, metabolism, bile secretion, hematopoiesis, blood storage, regulation of blood pressure circulation, immune defense and so on. The other meaning is a kind of test which can reflect whether the physiological function of the liver is normal, mainly including: bilirubin, albumin, globulin, transaminase, r-glutamyl transpeptidase, etc.

Physiological functions

Detoxification function

Most of the toxins (including drugs) consumed by the human body will be digested and absorbed by the human body through the detoxification function of the liver. At a certain level of liver damage (e.g., advanced cirrhosis, severe hepatitis), the liver's detoxification function begins to diminish and toxins begin to accumulate in the body, which will eventually lead to multi-organ failure and death in the human body.

Metabolic function

The human body takes in various nutrients (e.g. protein, fat, carbohydrates, etc.) every day, which are digested and absorbed by the gastrointestinal tract and then evacuated to the liver for decomposition before they become part of the body.

Secretion of bile

I'm sure we all understand the logic of liver and bile. The bile that we use to help digest and absorb food is secreted by our liver, and the bile secreted by the liver is first transported by the bile duct to the gallbladder for storage. When we eat, the gallbladder receives the corresponding instructions from the brain and starts to contract, delivering bile to the small intestine through the cystic duct and common bile duct to help it digest and absorb. If the bile ducts inside and outside the liver become blocked, bile accumulates in the bloodstream and jaundice can develop over time.

Hematopoiesis, blood storage, and regulation of circulating blood volume

During the eighth to twelfth weeks of embryonic development, newborns' blood production is mainly performed by the liver. When the liver matures, blood from the body enters the liver through two vessels, the portal vein and the hepatic artery, through the hepatic hilum, then it is distributed like a tree branch in the glandular vesicles of the liver, and finally converges to the main trunk of the hepatic vein into the inferior vena cava. Therefore, the liver is like a large blood bank in the human body, and the liver carries the mission of blood production, blood storage and blood circulation regulation throughout its life.

Immune function

It has been found through research that the liver contains sinusoidal cells and T lymphocytes. Because of the specific structure and function of these cells and their different sources of differentiation, which are interrelated and closely related to the activity of hepatocytes, they together constitute a micro-ecological environment of the liver's immune system.

The regenerative function of the liver

Experiments on mice in which 75% of the liver was removed and restored to its original state after 3 weeks have shown that more than 300 billion hepatocytes in the human body have a strong regenerative capacity and that when the liver is damaged by inflammation or other diseases, the liver can temporarily bring the body's functions into balance through its own regenerative function. However, the liver's powerful regenerative ability is what makes certain diseases not easily detected by patients. When the degree of liver damage increases and eventually exceeds the liver's own regenerative ability, liver decline and various complications will occur. A gentle reminder to all friends to be sure to have regular medical checkups, early detection and early treatment.

Analysis of liver function tests

Liver secretion and excretion dysfunction

The life span of human red blood cells is generally 100-120 days. When the red blood cells die, they turn into indirect bilirubin, which is then transformed into direct bilirubin by the liver and finally composed of bile and excreted out of the body through the bile duct. When any of the above mentioned links are damaged, it will affect the bilirubin excretion. The bilirubin content of liver function tests can be reflected in the normal bilirubin content: TBILI (total bilirubin) 5.1 to 19.0 = DBILI (direct bilirubin) 0.0 to 5.1 + IBILI (indirect bilirubin) 5.0 to 12.0. When the value of bilirubin exceeds the normal range, it can be clinically considered to be caused by viral hepatitis, toxic hepatitis , hemolytic jaundice, internal bleeding and other causes.

Liver cell damage

The basic serum enzymes in hepatocytes include: glutamate aminotransferase ALT (GPT), glutathione aminotransferase AST (GOT), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (gamma-GT or GGT), etc. When hepatocytes are damaged, serum enzymes in the blood will rise, and the values of these enzymes precisely reflect the corresponding pathological symptoms. changes in the values of ALT and AST are sensitive to the degree of hepatocyte damage, while alkaline phosphatase (ALP) and γ-glutamyl transpeptidase (GGT or γ-GT) are among the indicators commonly used in the diagnosis of biliary system diseases.

Impairment of hepatic synthetic storage function

The human blood contains albumin and immunoglobulin, which are produced by the liver. If there is a disruption in the metabolic function of the liver, the albumin will decrease, while the immunoglobulin G produced by the body's immune organs will increase to maintain the balance of body functions. Our common ascites is a clinical symptom of reduced albumin and reduced intravascular osmolarity. Therefore, the values of total protein (TP), albumin (ALB), immunoglobulin G, and prothrombin time (PT) in the blood truly reflect the normal metabolism of liver function (e.g., chronic hepatitis, cirrhosis, and other conditions can reduce albumin). The prolongation of prothrombin time (PT) time reflects the reduced ability of the liver to synthesize various coagulation factors. Once the coagulation function in the blood is affected, certain parts or organs will show clinical manifestations of bleeding and bruising.

Liver cirrhosis indicators

During liver function tests, the change in the ratio of albumin (ALB) to immunoglobulin G, or the A/G index, is an important indicator of liver fibrosis and cirrhosis, with a general A/G ratio of 1.5 to 2.5. If the degree of hepatitis increases, the A/G ratio will decrease, and when the A/G ratio is below 1, it indicates substantial liver damage, and the prognosis is generally poor.

Warm Tips

For the analysis of liver function test results, we patients should never judge a certain disease based on liver function test results alone. A professional doctor must determine a disease based on clinical experience and multiple test results, and develop the most perfect treatment plan, do not blindly use drugs on your own.