Blood test hemoglobin is a clinical study aimed at measuring the amount of erythrocyte protein that reflects the state of oxygen exchange between the lungs and body tissues. The study of hemoglobin concentration is carried out as part of a general blood test, other indicators are taken into account when interpreting the results. The data are used to determine the severity of anemia, polycythemia, evaluate the effectiveness of therapy for these diseases, as well as to monitor the state of health, to prepare for operations. Blood sampling is performed from capillaries or veins, the analysis is performed by colorimetric method. Indicators of the norm of hemoglobin in the blood for men – 135-160 g / l, for women – 120-140 g / l. The readiness of the analysis results is one working day.
Hemoglobin is a chromoprotein that is part of red blood cells. By its structure, it belongs to complex proteins, consists of four subunits, each of which is represented by a heme – a pigment component and a globin – an amino acid chain with an iron atom. The main function of hemoglobin is the transfer of oxygen from the lungs to the tissues. The quaternary structure of the protein provides the ability to attach and cleave O2 molecules. Normally, a hemoglobin unit is capable of transporting 4 oxygen atoms, such a complex is called oxyhemoglobin. Hemoglobin takes hydrogen and carbon dioxide from the tissues, transfers them to the lungs. Such complexes are called deoxyhemoglobin. Oxyhemoglobin and deoxyhemoglobin are two stable forms of protein that are normally present in red blood cells.
If hemoglobin binds to carbon monoxide (CO), a stable carboxyhemoglobin complex is formed, which is unable to carry oxygen. Such a pathological condition is observed with carbon dioxide poisoning. In some hereditary diseases, poisoning with nitric oxide, cyanide, hemoglobin iron changes its valence – methemoglobin is formed, unable to attach oxygen molecules to itself. With a reduced level of normal forms of hemoglobin in the blood, anemia develops – a condition in which the tissues of the body are not supplied with enough oxygen, which leads to fatigue, weakness, and a decrease in the functions of almost all organs. In addition, a lack of hemoglobin may be associated with a low level of red blood cells caused by their increased destruction, a decrease in production in the red bone marrow or loss as a result of bleeding.
Thus, the level of hemoglobin in the blood is an indicator of anemia. The material for analysis is venous blood. The most common method of studying the concentration of hemoglobin is colorimetry. The results are used in many areas of medical practice, most in demand in therapy, pediatrics, hematology, nephrology and surgery.
Blood test hemoglobin is often performed as part of a general blood test during preventive examinations, medical examinations in educational institutions, in the army, at work. The results reveal anemia and the risk of its development, allow for the necessary additional diagnostics, measures to prevent the disease and eliminate it at an early stage. In addition, the study of hemoglobin in the blood is indicated for symptoms of anemia – when the patient gets tired quickly, gets tired easily, constantly feels drowsy, experiences headache, dizziness, does not get enough sleep, cannot concentrate on work, hardly remembers new information, feels tingling and numbness in the hands and feet. The examination determines the pallor of the skin, cracks in the corners of the lips, dryness and dullness of the hair, pain in the tongue area.
When conducting a general blood test, the hemoglobin indicator reveals anemia in various conditions and diseases: with blood loss, including menstrual, with a lack of vitamin B12 and folic acid, with chronic renal failure, Crohn’s disease, hypothyroidism, gluten-dependent enteropathy, gastritis and gastric ulcer, oncological lesions, blood pathologies, etc. Therefore, the list of indications for determining the level of hemoglobin in the blood is very wide. In rare cases, the symptoms characteristic of elevated hemoglobin levels in the blood become the basis for the study. This condition is called polyglobulia and is manifested by redness of the skin, blueness of the nasolabial triangle, headaches and dizziness, decreased vision, a feeling of heaviness in the hypochondrium, shortness of breath, skin itching.
Hemoglobin test in the blood determines the presence of anemia and its severity, but does not indicate the cause. For a more complete examination, an additional test is prescribed for ferritin, serum iron, transferrin, erythropoietin, OZHSS. When interpreting the results, such indicators of the general blood test as the level of erythrocytes, erythrocyte indices (MCV, MCH, MCHC), hematocrit, ESR are taken into account. The advantage of the hemoglobin test is its availability and cost-effectiveness of the research procedure – the analysis is performed in any laboratory, the preparation of the results takes no more than 1 day.
Preparation for analysis
Blood sampling to determine the level of hemoglobin is performed in the morning. Between the last meal and the procedure, it is recommended to withstand 8-12 hours. It is permissible to donate blood 4-6 hours after a light snack. It is important to refrain from drinking alcohol 1 day before the analysis. The last half hour should be spent in a calm atmosphere, without physical and emotional stress, giving up smoking. A few days before the analysis, it is worth discussing with the doctor the need to cancel the medications taken.
The hemoglobin level is determined in blood taken from capillaries or from a vein. In the first case, a puncture of the ring finger is performed, in the second – a puncture of the ulnar vein. Currently, colorimetric research methods are used in laboratories: hemiglobin cyanide (HbCN), hemichromic (HBCHR) and hemiglobinazide (HBN3). Their essence lies in the fact that hemoglobin interacts with the reagent, resulting in the formation of a colored compound. The concentration of the studied protein is calculated from the optical density of the resulting mixture. The analysis is performed within 1 working day.
The normal hemoglobin level in boys over 16 years of age and men is 135-160 g/l. In women, the indicators are distributed in the corridor from 120 to 140 g / l, and at the beginning of the menstrual cycle they approach the lower border, in the middle and at the end – to the upper. In childhood, the normal values of hemoglobin are constantly changing, they need to be determined individually. In newborns in the first three days, the protein concentration ranges from 145 to 225 g / l. Then it gradually decreases:
- 3-7 days – from 135 to 215 g/l;
- 1-2 weeks – from 125 to 205 g/l;
- 2-4 weeks – from 100 to 180 g/l;
- 1-3 months – from 90 to 140 g/l;
- 3-6 months – from 95 to 135 g/l;
- from 6 to 12 months – from 100 to 140 g/l;
- 1-2 years – from 105 to 145 g/l;
- 2-7 years – from 110 to 150 g/l;
- 7-16 years – from 115 to 155 g/l.
As can be seen from the above norms, during the newborn period, the hemoglobin level is the highest. According to its properties, this protein differs from hemoglobin in adults, it is called fetal. In the absence of violations on the part of the blood system during the first year of life, it completely disappears. The concentration of hemoglobin in the blood increases with oxygen starvation associated with climbing to a great height or smoking. A physiological decrease in protein levels occurs during pregnancy, while following a vegetarian diet, immediately after taking blood for analysis.
The cause of polyglobulia or elevated hemoglobin levels in the blood may be true polycythemia– a disease in which tumor cells in the red bone marrow produce excessive amounts of red blood cells. This pathology is more often diagnosed in the elderly and senile age. The concentration of erythrocytes, and, consequently, hemoglobin, increases with secondary polycythemia. It develops with oxygen starvation caused by pathologies of the cardiovascular or respiratory system – chronic obstructive pulmonary disease, emphysema, pneumoconiosis, arteriovenous fistulas, congenital heart defects, etc.
In kidney diseases, the cause of an increase in hemoglobin levels in the blood is an increased production of erythropoietin, a substance that enhances the production of red blood cells in the red bone marrow. An increase in the analysis indicators is determined in kidney cancer, hypernephroma, polycystic kidney disease. After removal of the spleen, a slight increase in hemoglobin levels is associated with a longer lifespan of red blood cells, with dehydration – with blood thickening, increased hemoconcentration.
Decrease in hemoglobin levels
Anemia is one of the most common causes of a decrease in hemoglobin levels in the blood. Diseases of this group vary in origin, but they are all characterized by insufficient supply of oxygen to tissues. The basis of the violation of the transport function of red blood cells may be a deficiency of iron, folic acid and / or vitamin B12, increased breakdown of red blood cells, prolonged inflammation in the body, leading to iron retention in tissues, hypothyroidism, impaired hemoglobin production. Other causes of a decrease in the level of hemoglobin in the blood include acute and chronic bleeding, connective tissue diseases, chronic kidney disease, liver cirrhosis, thyroid dysfunction, the breakdown of red blood cells against the background of infections and poisoning with certain types of poisons.
Treatment of anomalies
Blood test hemoglobin is part of a general blood test. This is a simple and affordable method of primary detection of anemia, polycythemia, oxygen starvation conditions. In clinical practice, it is often used as part of screening and preventive examinations. With the results of the analysis, it is necessary to consult a general practitioner, pediatrician, hematologist or other specialist who sent for examination. To avoid a physiological increase or decrease in hemoglobin levels, you need to eat well, using sources of iron, vitamin B12, folic acid, as well as give up smoking, physical activity that does not correspond to the level of physical fitness.