Liver/Gallbladder ALAT, ASAT, bilirubin, alkaline phosphatase
Blood tests for liver disease, liver problems or to detect excessive alcohol consumption.
To check for jaundice, which can be caused by liver diseases and gallstones, among other things.
The following tests are performed:
- Bilirubin total
- Gamma-GT (GGT)
- ALAT (GPT)
- ASAT (GOT)
- Alkaline phosphatase
Bilirubin
Bilirubin is the breakdown product of hemoglobin and leaves the body through the feces. It first enters the gallbladder and is then excreted in the small intestine. In people with liver disease, bilirubin is sometimes not or not completely excreted, for example because the bile cannot leave the gallbladder properly due to gallstones. This results in a yellowish skin color, also called jaundice or icterus.
Increased bilirubin levels in the blood mean that the liver is not functioning optimally. An increased level of bilirubin in the blood is almost always accompanied by jaundice. First the whites of the eyes turn yellow and later the skin as well. This is because bilirubin has an intense yellow color.
There are many different liver diseases in which bilirubin levels are more or less elevated. For example, in:
- Cirrhosis of the liver
- primary biliary cirrhosis (PBC)
- different forms of hepatitis
- Gilbert syndrome
- Conditions in which the drainage of bile fluid is obstructed, such as gallstones, primary sclerosing cholangitis (PSC) and the congenital disease bile duct atresia.
Gamma GT
(GGT) is an enzyme made in the liver that helps convert and digest substances that enter the body through food and drink. Normally, the concentration of GGT in the blood is very low, but when the liver is under heavy stress, the amount can rise considerably. This happens when the liver is supplied with a lot of substances to process in a short period of time, for example with (extreme) use of medicines or alcohol. GGT will also rise if the bile ducts are blocked, if there are gall bladder problems, or as a result of liver damage.
ALAT
The test determines the amount of the enzyme ALT in blood. An enzyme is a protein that helps cells to convert a certain substance into another substance. ALT is mainly present in the liver. Smaller amounts are found in the kidneys, heart, and muscles. Normally the amount of ALT in the blood is low. If liver cells are damaged, ALT leaks from the liver into the blood. This causes the amount of ALT in the blood to increase. This can happen before there are any complaints or symptoms (such as jaundice, yellow eyes or skin) that indicate liver damage.
ASAT
The test also determines the amount of the enzyme aspartate aminotransferase (ASAT) in blood. An enzyme is a protein that helps cells convert one substance into another. ASAT is present mainly in the liver and in transverse muscle tissue (heart and skeletal muscle). Normally, the amount of ASAT in the blood is low. When liver or muscle cells are damaged, ASAT is released into the blood.
Alkaline phosphatase
Alkaline phosphatase (AF) is examined when liver or bile duct problems are suspected. It is often determined together with ASAT, ALAT and Gamma-GT. The main causes for elevations of alkaline phosphatase in the blood are disorders of the liver, bile ducts or skeleton.
Alkaline phosphatase (AF) is an enzyme that can remove phosphate groups from various molecules, such as nucleotides, proteins, etc. AF detectable in the blood is mainly derived from liver parenchyma, bile duct epithelium and osteoblasts. To a lesser extent, it is also produced by and intestinal epithelium, placenta and renal tissue.
With regard to bone diseases, it is often seen as a measure of osteoblast activity. Alkaline phosphatase is therefore requested in the diagnosis and follow-up of liver disease, bile duct problems and bone diseases.
If an elevated concentration of alkaline phosphatase is measured in addition to an elevated and gamma-glutamyltransferase, there may be liver disease, whereas an isolated alkaline phosphatase elevation may be a sign of bone disease, such as Paget's disease.
Increases in blood AF not associated with "disease" are seen during pregnancy and in the recovery phase after bone fractures.
Elevation may occur with liver abnormalities such as hepatitis, cirrhosis, or a space occupying process. Another important reason for elevation is an obstruction of the bile ducts, then bile cannot drain properly from the gallbladder. Fatty meals, pregnancy, or kidney failure can also play a role in elevated alkaline phosphatase giving.
Lowered alkaline phosphatase occurs in menopausal women taking estrogen for osteoporosis. But also in people with malnutrition, magnesium deficiency, anemia, a slow-working and thyroid gland or after a severe period of diarrhea.
Some medications can affect the outcome of determinations: for example, corticosteroids increase alkaline phosphatase.
