Phosphatase alkaline - an important enzyme of the human body

To date, in the complex diagnosis of many diseases, laboratory methods of examination are used. In this case, a biochemical blood test is performed.

Alkaline phosphatase: a 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 liver cells and kidney tubules, in the intestinal mucosa, as well as in the placenta. Phosphatase alkaline, which is contained in serum, usually comes from bone tissue or hepatocytes. Its high activity is observed mainly in liver diseases, which occur with obstruction of the bile ducts, as well as in bone lesions, which are accompanied by remodeling of bone tissue.

The level of alkaline phosphatase is high. Why?

There are many pathological conditions in which alkaline phosphatase increases. The norm of this indicator depends on age and sex, so this is taken into account when interpreting the 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;

• Inadequate intake of calcium and phosphate from food;

• excess ascorbic acid in the body;

• use of certain pharmacological agents (for example, contraceptives containing estrogen and progesterone, as well as antibiotics).

In addition, alkaline phosphatase can be increased in the following diseases:

• Hyperparathyroidism;

• Infarction of the kidney or lung tissue;

• Myeloma;

• Infectious mononucleosis;

• damage to bones, including cancerous nature;

• lymphogranulomatosis, which occurs with the destruction of bones;

• rickets;

• malignant lesion of the biliary tract;

• inflammation of infectious nature or cirrhosis of the liver, its tuberculous lesion.

Etiology of alkaline phosphatase reduction

There are a number of pathologies in which, on the contrary, alkaline phosphatase decreases. So, the level of this enzyme is lower than normal for hypothyroidism. Disturbance of bone growth, deficiency of zinc and magnesium, as well as anemia are the etiological factors that can affect the amount of alkaline phosphatase in the blood serum. Taking certain medications also changes the results of the tests. In addition, the presence of scurvy, which develops due to deficiency 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 number of placental isoenzyme. This is typical for the final term of pregnancy and is associated with the maximum development of the placenta. This pattern has no diagnostic value, so it is not used to assess the state of the mother or fetus. In cases when a woman is diagnosed with placental insufficiency, the concentration of this enzyme compound is reduced.

Features of changes in the level of alkaline phosphatase

Phosphatase alkaline occurs in the form of several isoenzymes. The degree of increase in the concentration of this compound correlates with osteoblastic activity (with the process of bone formation), therefore the highest level of bone isoenzyme is observed with Paget's disease. If the patient develops pathologies with osteolytic activity (eg, myeloma), then alkaline phosphatase increases, but insignificantly.

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 liver cells can occur against a background of normal or even low levels of alkaline phosphatase. This pattern is typical, as a rule, for the majority of clinical cases, although it may not be observed in a specific patient, even if the liver or biliary tract is affected.

It should be noted that the alkaline phosphatase in a child is increased - a physiological phenomenon, which is associated with active growth. So, the level of this enzyme in childhood can reach a level that exceeds the norm for an adult person by a factor of 1.5-2 (from 82 to 341 U / l).

Specificity of alkaline phosphatase

To date, the optimal conditions for the analysis of the determination of the 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 uniform boundaries of the indicator "alkaline phosphatase", so do not compare the values of this enzyme, which were obtained in different laboratories. Especially it concerns cases when it is not known what standards these laboratories establish.

Serum is used for analysis. In most cases, take the top layer, which is formed in a separator tube. It is worth noting that the level of alkaline phosphatase may be erroneously increased, if a blood sample is harvested on the upper limb for more than 30 seconds. In addition, the activity of this enzyme may vary slightly if blood samples are stored at room temperature. In this case, hemolysis in the test tube does not affect the results of the analysis.

What should I do if I have a pathological level of alkaline phosphatase?

When alkaline phosphatase is increased, treatment should be etiologic. So, in the presence of diseases of the liver or bile ducts, it is worth consulting with a gastroenterologist. Cholestasis, the presence of pancreatitis, alcoholic hepatitis or cirrhosis of the liver requires an appropriate drug correction, the volume of which is determined only by the doctor. Self-medication in this case can lead to an exacerbation of the underlying disease.

The change in the concentration of enzymes, including alkaline phosphatase, can be observed in heart failure, cancer pathologies and severe kidney damage, as well as diabetes mellitus, so it is worth consulting with a cardiologist, nephrologist or endocrinologist. The doctor will determine the therapeutic tactics depending on the clinical picture.

With the elimination of etiological factors, the activity of alkaline phosphatase returns to normal. When prescribing therapy, it should be taken into account that, for example, the physiological increase of this index is possible with fractures, active growth of the osseous system, when the fetus is born. It does not require medical intervention. Interpretation of the results of laboratory tests should be carried out in a comprehensive manner, taking into account other biochemical indicators and complaints of the patient.