In the previous articles, we explained the role of the liver, the precautions for liver function tests, and the significance of changes in serum enzymological test indicators. What do the changes in the indicators represent? (i)
Today we pick up the book and continue to talk about the other two groups of routine liver function tests: serum protein tests, and bilirubin and bile acid metabolism tests.
01 Serum protein test
Reflects the functional status of the liver in synthesizing proteins
Serum protein tests include total protein (TP), albumin (ALB), globulin (GLB), and prealbumin (PA).
Total protein (TP) is the sum of albumin (ALB) and globulin (GLB). In the clinic, globulins are not detected alone, but the total protein is subtracted from albumin to obtain the value of globulin.
While 90% of the total protein and all albumin are synthesized by the liver, the total protein and albumin (ALB) content is an important indicator of the liver's synthetic function.
Prealbumin (PA), a new test that has emerged in recent years, is similar to albumin function. Due to the small molecular weight and short half-life of prealbumin, once the body is damaged, prealbumin will be released into the bloodstream earlier than albumin.
In general, if there is a slight damage to the liver, it often first manifests as abnormalities in prealbumin and albumin, and the abnormalities in globulins do not appear until the middle of the damage.
Elevated total protein (TP), albumin (ALB), and prealbumin (PA) may be due to severe dehydration, shock and other factors caused by reduced water in the blood, and protein is relatively concentrated, resulting in elevated indicators.
Decreased total protein (TP), albumin (ALB), and anterior albumin (PA) indicate impaired liver function, which can be seen in subacute severe hepatitis, chronic severe hepatitis above severe disease, cirrhosis, ischemic liver injury, and liver cancer;
It may also be due to inadequate protein intake, indigestion and malabsorption, or increased consumption from chronic wasting diseases, and patients tend to experience symptoms of wasting.
In the clinic, it is believed that the decrease in serum protein values is more clinically significant and needs to be paid attention to.
The total protein and albumin content is not related to sex, but it is related to age, and the average newborn and infant is slightly lower, and the elderly after the age of 60 will also be slightly reduced.
02 Bilirubin metabolism test
Identify the type and severity of jaundice
Bilirubin metabolism test mainly includes three indicators: total bilirubin (TBIL), binding/direct bilirubin (DBIL), and unbound/indirect bilirubin (IBIL).
Bilirubin (BIL) is mainly produced by the catabolism of heme in hemoglobin, which is non-binding/indirect bilirubin (IBIL) before entering hepatocytes, which is taken up by hepatocytes and bound to glucuronic acid to form binding/direct bilirubin (DBIL), which sums up as total bilirubin (TBIL).
Adult total bilirubin (TBIL) normal range of 3.4 ~ 17.1 μmol / L, if the total bilirubin in 17.1 ~ 34.2 μmol / L is a hidden jaundice, at this time the skin may not have the naked eye visible yellowing, if the total bilirubin is greater than 34.2 μmol / L is dominant jaundice, you can see the skin yellowing.
Bilirubin index is an important basis for judging the degree of jaundice and liver damage, if the production of bilirubin is too much, or the liver cells to the uptake, binding and excretion of bilirubin is obstructed, the blood bilirubin concentration can increase, hyperbilirubinemia or jaundice.
Elevated indirect bilirubin (IBIL) suggests possible haemolytic jaundice, which is generally mild.
Elevated indirect bilirubin (IBIL) and direct bilirubin (DBIL) suggest that hepatocellular jaundice, or jaundice due to liver damage, is mostly mild to moderate jaundice.
Elevation of direct bilirubin (IBIL) predominates, suggesting possible cholestatic jaundice, often moderate jaundice, or severe jaundice if complete obstruction occurs.
03 Total bile acid (TBA) metabolism test
Reflects liver cell function
Bile produced by the liver, one of the important components of which is bile acids, plays an important role in regulating fat and cholesterol metabolism. Total bile acids (TBAs) can be sensitive to the functional state of liver cells in synthesis, uptake, secretion, and excretion.
At the same time, because the excretion and utilization of bile are related to the biliary tract and intestine, total bile acid (TBA) can also reflect lesions of the intestine and biliary tract.
In general, elevated total bile acid (TBA) can indicate liver damage and reduced hepatocyte function, mainly in acute hepatitis, chronic active hepatitis, cirrhosis and liver cancer, etc.; may also indicate cholestasis, which is seen in intrahepatic and extrahepatic bile duct obstruction diseases such as cholelithiasis and biliary tract tumors, or some intestinal diseases.
If the total bile acid (TBA) decreases during the treatment of the disease, it indicates that the treatment effect is better, on the contrary, if the total bile acid (TBA) does not decrease or even continues to rise during treatment, the treatment effect is not good.
A simple decrease in serum total bile acid (TBA) generally does not have much clinical significance.
References: Medical Microvision official website - Han Chengwu Chief Technician "Liver Function Test"