To date, laboratory methods of examination are used in the complex diagnosis of many diseases. In this case, a biochemical blood test is performed.
Alkaline phosphatase: general characteristic of the enzyme
Alkaline phosphatase is one of the important indicators. This compound is an enzyme that exhibits phosphatase activity. It is present in almost all cells of the human body. Its maximum activity is manifested in an alkaline environment and is associated with cell membranes. The highest concentration of this compound is recorded in osteoblasts ( bone cells), in the cells of the liver and renal tubules, in the intestinal mucosa, as well as in the placenta. Alkaline phosphatase, which is found in blood serum, usually comes from bone tissue or hepatocytes. Its high activity is mainly observed in liver diseases that occur with obstruction of the bile ducts, as well as in bone lesions that are accompanied by bone remodeling.
The level of alkaline phosphatase is high. Why?
There are many pathological conditions in which alkaline phosphatase rises. The norm of this indicator depends on age and gender, so this is taken into account when interpreting a biochemical blood test.
Among the etiological factors that can affect the level of enzymes, including alkaline phosphatase, the following should be mentioned:
• pregnancy;
• the period after menopause;
• insufficient intake of calcium and phosphates with food;
• excess ascorbic acid in the body;
• the use of certain pharmacological preparations (for example, contraceptives containing estrogen and progesterone, as well as antibiotics).
In addition, alkaline phosphatase can be increased in the following diseases:
• hyperparathyroidism;
• heart attack of a kidney or lung tissue;
• myeloma;
• Infectious mononucleosis;
• bone lesions, including cancerous nature;
• lymphogranulomatosis, which proceeds with the destruction of bones;
• rickets;
• malignant lesion of the biliary tract;
• inflammation of an infectious nature or cirrhosis of the liver, its tuberculous lesion.
Etiology of a decrease in alkaline phosphatase
There are a number of pathologies in which, on the contrary, alkaline phosphatase decreases. So, the level of this enzyme is below normal in hypothyroidism. Impaired bone growth, zinc and magnesium deficiency, and anemia are etiological factors that can affect the amount of alkaline phosphatase in blood serum. Taking certain medications also changes the results of the tests. In addition, the presence of scurvy, which develops due to a lack of ascorbic acid, leads to a decrease in this enzyme.
It should be noted that during pregnancy, alkaline phosphatase can grow due to an increase in the amount of placental isoenzyme. This is typical for the final stages of pregnancy and is associated with the maximum development of the placenta. This pattern has no diagnostic value, therefore, it is not used to assess the condition of the mother or fetus. In cases where a woman is diagnosed with placental insufficiency, the concentration of this enzyme compound decreases.
Features of changes in alkaline phosphatase level
Alkaline phosphatase is in the form of several isoenzymes. The degree of increase in the concentration of this compound correlates with osteoblastic activity (with bone formation), therefore, the highest level of bone isoenzyme is observed with Paget's disease. If a patient develops pathologies with osteolytic activity (for example, myeloma), then alkaline phosphatase increases, but not significantly.
With lesions of the
hepatobiliary system , the hepatic isoenzyme increases. In clinical practice, it is used as a marker of cholestasis. In this case, direct damage to the liver cells can occur against a background of normal or even reduced levels of alkaline phosphatase. This pattern is typical, as a rule, for most clinical cases, although it may not be observed in a particular patient, even with damage to the liver or biliary tract.
It should be noted that alkaline phosphatase in a child is increased - a physiological phenomenon that is associated with active growth. So, the level of this enzyme in childhood can reach a level that exceeds the norm for an adult by 1.5-2 times (from 82 to 341 units / l).
The specifics of determining the level of alkaline phosphatase
To date, the optimal conditions for analyzing the determination of alkaline phosphatase concentration are different, since each laboratory has its own standards. There are several research methods that depend on the enzyme substrate and the buffer system, as well as on the temperature at which the samples are taken. There are no common boundaries for the “alkaline phosphatase” indicator, so do not compare the values of this enzyme that were obtained in different laboratories. This is especially true when it is not known what standards these laboratories set.
For analysis, blood serum is used. In most cases, take the top layer, which is formed in a separator tube. It is worth noting that the level of alkaline phosphatase can be erroneously increased if, during blood sampling, a tourniquet on the upper limb was applied for longer than 30 seconds. In addition, the activity of this enzyme may vary slightly if blood samples are stored at room temperature. Moreover, in vitro hemolysis does not affect the results of the analysis.
What to do with a pathological level of alkaline phosphatase?
When alkaline phosphatase is increased, treatment should have an etiological direction. So, in the presence of diseases of the liver or bile ducts, it is worth consulting a gastroenterologist. Cholestasis, the presence of pancreatitis, alcoholic hepatitis or cirrhosis requires appropriate medical correction, the amount of which is determined only by a doctor. Self-medication in this case can lead to an exacerbation of the underlying disease.
A change in the concentration of enzymes, including alkaline phosphatase, can be observed with heart failure, cancer pathologies and severe kidney damage, as well as diabetes, so you should consult a cardiologist, nephrologist or endocrinologist. The doctor will determine the therapeutic tactics depending on the clinical picture.
When etiological factors are eliminated, alkaline phosphatase activity returns to normal. When prescribing therapy, it should be borne in mind that, for example, a physiological increase in this indicator is possible with fractures, active growth of the skeletal system, and with the bearing of the fetus. It does not require medical intervention. Interpretation of the results of laboratory tests should be carried out comprehensively, taking into account other biochemical parameters and patient complaints.