We all turn to doctors, and the first thing our communication begins with is laboratory research. And if for a specialist the data indicated on the obtained results are understandable, then even a simple decoding of a blood test often baffles an ordinary person. HCT - this is what a hematocrit parameter is now called - is an important indicator of human health. We will tell you more about it.
Hematocrit - what is it
Hematocrit is one of the conditional indicators of blood. It shows the percentage of the mass of red blood cells to the total volume of biological fluid. The HCT indicator (blood test), the decoding of which can also be interpreted as the ratio of all formed blood elements to plasma, most often determines the volume of red blood cells, because they make up 99% of the total number of blood cells.
The official name for this parameter is the hematocrit, and in popular speech it is often called "blood density." Hematocrit is a flask that is used to centrifuge biomaterial, but its name has taken root so well that it is often used in official medicine.
How is hematocrit determined?
As you know, blood consists of plasma (liquid part) and cells. Plasma is water in which proteins, enzymes, hormones, trace elements are dissolved. Cells, represented by red blood cells, white blood cells and platelets, have a different structure and perform dissimilar functions. When a blood test transcript occurs, HCT is determined visually. For analysis, the selected venous or capillary blood is placed in a test tube and centrifuged after adding an anticoagulant to it. At the same time, denser and heavier cells settle. The lower layer consists of red blood cells, the middle - white blood cells and platelets, and the plasma remains on top. After that, a measurement takes place. So, for example, if the result indicates that 40% HCT (blood test), decoding will mean that in a test tube with 100 μl of blood after it was passed through a centrifuge, 40 μl is occupied by red blood cells.
To date, there are two methods for determining hematocrit. Do this using a centrifuge (in this case, the indicators will be indicated in percent) and using an automatic hematological analyzer. In a recent study, the transcript of a general HCT blood test will be defined as the ratio of liters to liters (l / l). It will look like this:
- when tested in a centrifuge - 35%;
- when using a hematological analyzer - 0.35 l / l.
HCT (blood test), transcript. Norm
Hematocrit is not a constant indicator. In men, it is often higher than in women. What are the normal HCT values? A blood test (transcript) in children of the first year of life often shows significant differences from that in adults. As the patient grows older, this value gradually decreases. Pregnancy also affects this indicator. Under normal conditions, the hematocrit slightly decreases.
The following HCT values are considered normal (blood test, transcript):
- the norm in children of the first week of life is 42–66%, from 6 months to 2 years old –33–39%, from 2 to 6 years old –– 35–45%, from 6 to 15 years –– 36–49%;
- for girls from 15 to 18 years old, hematocrit can be from 36 to 46%, and for boys - 37–49%;
- in women, the hematocrit is normal from 33 to 47%;
- in men - 39-51%.
As you can see, the indicators have a fairly wide scatter. In addition, when considering the results, it must be borne in mind that external factors can also influence them. So, for example, taking certain medications (alpha-interferon, blood thinners) can significantly affect the result.
Why is the analysis prescribed?
When a blood test is decrypted, HCT is one of its indispensable indicators, so it is always evaluated. This indicator has diagnostic value in the following cases:
- to confirm the diagnosis of anemia;
- with polycythemia (a group of diseases characterized by an increase in the number of red blood cells);
- with polyglobulia (diseases associated with a high level of protein in the blood);
- for control in the treatment of anemia.
In addition, when a transcript of a blood test is performed for severe patients, HCT allows you to determine the presence of internal bleeding, the level of dehydration. It is also an important indicator for patients after a blood transfusion, as it helps to evaluate the effectiveness of the measures taken.
HCT (blood test), transcript. Reduced value
Most often, a decrease in hematocrit can be observed with hypoplastic anemia. With this disease, the level of HCT can decrease to 15-25%. Symptomatically, this can be manifested by constant fatigue, headaches, dizziness, weakness. From the side of the cardiovascular system, tachycardia (increased heart rate), shortness of breath are observed. Externally, pallor of the skin, hair loss, brittle nails are noted.
Hyperhydration may be another cause of low hematocrit . This pathology, characterized by an excess of water in the blood, can be the result of renal failure, poisoning, viral or infectious diseases.
Hyperproteinemia (an increase in the amount of protein in the blood) can also be accompanied by a low hematocrit. The reason for the increase in blood proteins is liver pathology (hepatitis, cirrhosis), malignant tumors, prolonged fever, intoxication, chronic heart and kidney diseases.
HCT during pregnancy
The decrease in hematocrit during pregnancy is physiological. However, a gynecologist conducting a pregnancy is required to determine in a timely manner when lower rates indicate the development of anemia. For this, a blood test is regularly done. HCT (normal) in women expecting a baby ranges from 31 to 35%. Its increase above 36% can signal dehydration, and indicators above 40% already indicate pronounced hypovolemia (a decrease in the volume of circulating blood). The reason for this may be constant vomiting, swelling, excessive intake of salts.
A decrease in the hematocrit in a pregnant woman below 30% can be a signal of increasing anemia, which means that the cells do not receive enough nutrients and oxygen. In addition, this leads to an overload on the heart, kidneys and other organs. Another reason for the decrease in hematocrit is hyperhydration caused by the introduction of large volumes of intravenous infusions.
HCT increased
When the hematocrit index is above 55%, we can talk about its increase. First of all, this means that too many cellular elements become in the blood, that is, its viscosity increases. This threatens with increased thrombosis. Thrombosis can lead to the development of complications that can be fatal. The following conditions can become the cause of elevated hematocrit:
- erythrocytosis, both primary (erythemia), and secondary, which can be caused by oxygen starvation;
- pathology of the kidneys, which are accompanied by increased synthesis of erythropoietin;
- hydronephrosis or polycystic kidney disease;
- a decrease in the volume of circulating blood (may be the result of a burn disease, peritonitis, bleeding);
- dehydration.
What affects hematocrit
Despite all of the above, a moderate increase or decrease in hematocrit is not always a sign of the development of any pathology. Its increase may be associated with a slight dehydration of the body. Often this affects sedentary people who use little fluid. Increased hematocrit may result from profuse sweating, diarrhea, or vomiting.
High HCT can be observed in peoples living at high altitudes. The reason for this is constant hypoxia. Adapting to it, the body increases the number of red blood cells.
Hematocrit increased in athletes using anabolic steroids. If the blood test showed an HCT above 50% (0.5), then the athlete is not allowed to participate in the competition as doping.
Smoking can also cause increased hematocrit. This habit makes the body in a state of constant oxygen starvation, which stimulates the production of red blood cells. As a result, the hematocrit increases, so even in a healthy smoker it will be higher than in a non-smoker.