Haptoglobin - what is it? Indicators of the norm
Young blood cells are replacing aged and dead red blood cells that have lost the ability to function fully. What happens with the hemoglobin (Hb), which is part of these cells, which contains iron, which is valuable for the body? Since it is able to pass through the glomeruli of the kidneys, it means that it is possible to dissolve in the blood plasma and, leaving the body, remove iron.
The protein haptoglobin (Haptoglobin - HPT, Hp), present in human blood, binds hemoglobin and thus forms a dispersed complex of increased severity.
This compound is unable to cross the narrow channels of the glomeruli of the kidneys, and hemoglobin remains in the body. The term "haptoglobin" comes from the Latin "hapto" - to bind.
Blood plasma is able to dissolve hemoglobin in a volume of 0.01-0.03 g / l. If its concentration in the blood is significantly increased, haptoglobin is unable to bind all the available hemoglobin. In this case, the red blood pigment in the plasma enters the kidneys, where filtration takes place. This is how hemoglobinuria (protein in the urine) and other complications occur. This situation most often occurs as a result of blood transfusion.
Content:
- About the norm of haptoglobin in the blood
- Haptoglobin in the human circulatory system
- What does the increase in haptoglobin say?
- What does the decrease in haptoglobin say?
- Features of haptoglobin
About the norm of haptoglobin in the blood
Normally, haptoglobin successfully performs the functions assigned to it. The table shows the age norms for this protein.
|
Age |
Norm, mg / l |
|
Infants up to six months of age |
50 - 480 |
|
Children from 6 months and adolescents up to 16 years |
250 - 1380 |
|
Adults from 16 to 60 years old |
150 - 2000 |
|
People over 60 |
350 - 1750 |
In the specialized medical literature, other ranges of the norm of haptoglobin may be given. this is because each laboratory has its own reference values. To determine the concentration of haptoglobin, blood serum taken on an empty stomach is analyzed using the immunoturbidimetric method. When detecting this glycoprotein, modern high-precision biochemical analyzers are used.
Haptoglobin in the human circulatory system
Haptoglobin is produced by cells of the liver parenchyma. In the blood, it is represented by three hereditary phenotypes: HPT 1-1, HPT 2-1 HPT 2-2. Constantly present in the blood plasma, Haptoglobin takes up 1.4% of the total protein.
Metabolic stages of HPT:
- The protein binds to the hemoglobin released from the destroyed blood cells.
-
In connection with it, it creates a dispersed Hp-Hb complex, which is directed to the system of macrophages that process waste biomaterial.
- Under the action of macrophages, iron molecules are released.
- The released iron enters the circulatory system, where it combines with the protein transferrin and together with it enters the bone marrow to participate in the formation of new erythrocytes.
The functioning of haptoglobin is aimed at the intermediate stage of iron metabolism, preventing the valuable element from leaving the body through the urinary system.
Since Haptoglobin has a high peroxidase activity, in addition to binding hemoglobin, it inhibits lipid oxidative processes.
What does the increase in haptoglobin say?
The concentration of haptoglobin increases with the following diseases and conditions:
- Large focal myocardial infarction;
- Actively flowing rheumatic heart disease;
- Acute phase of the inflammatory process;
- The presence of a tumor;
- Nephrotic syndrome, expressed in severe kidney pathology due to impaired metabolism of lipids and proteins;
- Lymphogranulomatosis;
- Rheumatoid arthritis;
- Stagnation of bile and impaired excretion;
- Hormone therapy with corticosteroids.
What does the decrease in haptoglobin say?
At any stage in the life cycle of red blood cells (erythrocytes), a drop in the concentration of haptoglobin can occur.
Types of hemolysis that cause a decrease in haptoglobin levels:
-
Isoimmune - occurs with blood transfusion that is incompatible in the group (for example, repeated transfusion of Rh-positive blood to an Rh-negative recipient);
- Autoimmune - occurs when antibodies are formed directed to their own antigens;
- Mechanical - arises as a result of severe injury, when replacing heart valves with artificial analogues;
- Medication - occurs when taking drugs based on pyrazole: Antipyrine, Amidopyrine, Analgin, or when taking sulfonamides;
- Infectious - occurs with malaria, bacterial endocarditis;
- Hemolysis in acute or chronic inflammation of the liver parenchyma.
The following pathologies cause a similar effect: enlargement of the spleen, abnormalities of erythrocyte membranes, hemoglobinopathies, anemia caused by folic acid deficiency, deficiency of glucose-6-phosphate dehydrogenase.
Features of haptoglobin
The behavior of haptoglobin sometimes differs from the functioning of analogous acute phase proteins. Since it is produced by the parenchyma of the liver, its hepatocytes contribute to an increase in HPT in the blood. But the analysis for blood biochemistry does not always confirm the fact of an increase in the concentration of haptoglobin.
With hemolysis accompanying acute inflammatory reactions, the amount of hemoglobin in the blood is very high. It is required to create heavily dispersed complexes and transport them to the macrophage system. In this case, the concentration of Haptoglobin should decrease. To obtain an objective picture without taking into account the effect of hemolysis, it is important to compare the results obtained with similar tests obtained when diagnosing other proteins from the category of acute phase proteins.
The author of the article: Shutov Maxim Evgenievich | Hematologist
Education: In 2013 he graduated from the Kursk State Medical University and received a diploma "General Medicine". After 2 years, completed residency in the specialty "Oncology". In 2016 completed postgraduate studies at the National Medical and Surgical Center named after N. I. Pirogov.
