Alkaline phosphatase (ALP or AKP) is an enzyme that is widely distributed in human liver, bones, intestines, kidneys, placenta and other tissues and is excreted out of the bile through the liver. This enzyme can catalyze the removal of the 5′ phosphate group from nucleic acid molecules, thereby converting the 5′-P end of the DNA or RNA fragment into a 5′-OH end. But it is not a single enzyme, but a group of isoenzymes. Six isoenzymes, ALP1, ALP2, ALP3, ALP4, ALP5 and ALP6, have been discovered so far. Among them, types 1, 2, and 6 are all from the liver, type 3 is from bone cells, type 4 is produced from placenta and cancer cells, and type 5 is from small intestinal villous epithelium and fibroblasts.
Reference value of alkaline phosphatase
The reference value of alkaline phosphatase will differ depending on the testing method or population. The normal value range also varies with each hospital. The method used depends on the instrument. Under normal circumstances, the normal reference values of alkaline phosphatase are: 50~135U/L for women and 45~125U/L for men.
Anything beyond this range can be considered to be on the high side. High levels of alkaline phosphatase are more common in developing children, pregnant women, and people in the healing period of fractures.
Clinical significance
Clinical measurement of ALP is mainly used for the diagnosis and differential diagnosis of bone and hepatobiliary system diseases, especially the differential diagnosis of jaundice. For unexplained high ALP serum levels, isoenzymes can be measured to help determine the organ source.
What is the reason for high alkaline phosphatase?
Physiological factors
1. During the physiological bone development period of children, alkaline phosphatase activity can be 1 to 2 times higher than that of normal people. In osteoporosis, alkaline phosphatase activity Enzymes are normal.
2. The level of serum alkaline phosphatase can increase in adolescents in the growing period, pregnant women, and after eating foods with high fat content and after strenuous exercise.
3. Pregnancy can lead to an increase in serum alkaline phosphatase levels, which can reach 2 to 3 times the normal level in the ninth month of pregnancy.
Pathological factors
1. Various hepatobiliary diseases can increase serum alkaline phosphatase levels. When extrahepatic biliary obstruction occurs, serum alkaline phosphatase levels can reach the reference value. The upper limit is more than 3 times, and the more complete the obstruction, the higher the alkaline phosphatase level. Serum alkaline phosphatase levels increase to a smaller extent in intrahepatic biliary obstruction.
2. Alkaline phosphatase is also significantly elevated in primary and secondary liver cancer, which is related to the increased synthesis of alkaline phosphatase by liver cells in cancer tissue or around cancer.
3. In other tumors such as breast cancer, lung cancer, ovarian cancer, osteocytoma, osteosarcoma, etc., when alkaline phosphatase increases, it indicates possible liver metastasis.
4. Patients with osteitis deformans have the highest serum alkaline phosphatase levels, often reaching 10 to 25 times the upper limit of the reference value; patients with osteoblast carcinoma also have high levels of alkaline phosphatase; in osteomalacia, Alkaline phosphatase levels are moderately elevated; serum alkaline phosphatase levels in patients with rickets can rise to 2 to 4 times the upper limit of the reference value. In both diseases, alkaline phosphatase levels gradually decreased after vitamin D treatment. There may be a temporary increase in alkaline phosphatase levels during the fracture healing period.
3. Elevated alkaline phosphatase activity can also be seen in thyroid and parathyroid pigment gland hyperfunction, renal tubular acidosis, hereditary phosphatase excess and other diseases.
6. Many drugs can increase alkaline phosphatase, such as barbiturates, antibiotics (kanamycin, gentamicin, chloramphenicol, ampicillin, erythromycin, etc.).
Generally speaking, the reasons for low alkaline phosphatase are
1. Low alkaline phosphatase caused by anemia.
2. Low alkaline phosphatase caused by thyroid insufficiency in children.
3. Low alkaline phosphatase caused by severe chronic gastritis.
4. During viral infection, its activity is within the normal range or slightly lower, resulting in low alkaline phosphatase.
5. Malnutrition, cretinism, vitamin C deficiency, scurvy, celiac disease, cachexia, low alkaline phosphatase caused by hereditary hypophosphataseemia.
What should I do if alkaline phosphatase is too high?
First of all, we must clarify the cause of high alkaline phosphatase. Since there are many reasons for high alkaline phosphatase, it is recommended to go to a regular hospital for B-ultrasound and other related examinations to find out the cause and treat it in time.
Elevated alkaline phosphatase indicates skeletal diseases such as rickets, rickets, bone malignant tumors, malignant tumor bone metastasis, etc.; hepatobiliary diseases such as extrahepatic bile duct obstruction, liver cancer, cirrhosis, capillary hepatitis, etc. ;Other diseases such as hyperparathyroidism. Different methods need to be adopted according to different diseases.
After reading the above introduction, now you know what causes high alkaline phosphatase. You don’t need to worry too much if alkaline phosphatase is high. It may also be caused by physiological factors. Therefore, it is best to do further examination to clarify the cause.
What should I do if alkaline phosphatase is low?
Low alkaline phosphatase is generally a pathological cause. If it is detected that your own alkaline phosphatase is low, generally if the value is close to the normal reference value, there will be no problem. However, when the value is much lower than the normal value of alkaline phosphatase, you should pay attention and go to the hospital for treatment in time.
