Hematocrit

definition

In which Hematocrit is it a Blood countwhich only the cellular components (more precisely the number of Erythrocytes) of the blood.

Generally blood consists of one liquid part, the Blood plasma and from many different cells. As already mentioned, these cells are summarized as hematocrit (abbreviation Hkt), whereby the value actually only refers to the erythrocytes.

However, since the cellular portion of human blood consists of more than 95% of erythrocytes, i.e. cells that are responsible for our oxygen being distributed throughout the body via the blood, the Hematocrit value defined as cellular blood count. The remaining 5% of the cells in the blood consist of the Platelets (Platelets), the cells of the acquired Immune defense (Lymphocytes) and the cells of the innate immune system (leukocytes and monocytes). The hematocrit value is measured in both small and large Blood count indicated and is an important parameter to describe the composition of our blood and can also be indirect Hints on a Anemia, that is, anemia.

Determination of the hematocrit

Of the Hematocrit value is part of a Blood count test always specified. In order to determine the hematocrit value, blood must be taken from the patient, with it it is not important whether the patient is sober (i.e. has not eaten or drunk anything) or whether the patient has consumed food.

In order to preserve only the cellular parts of the blood, the blood must be in a centrifuge be given, in this, due to gravity, the cellular parts (i.e. the erythrocytes) migrate downwards, during the liquid blood plasma fraction remains on the surface. This means that you can see with the naked eye exactly where the boundary between the cellular blood content (hematocrit) and blood plasma is. However, a so-called Blood smear made to determine the number of individual cells. Since the blood must not clump (clot) beforehand, which would happen automatically in the air outside the body, the blood must first have the Anti-coagulant EDTA or Heparin be admitted.

Normal hematocrit

Usually should be a Hematocrit value at Women between 37-45% lie with Men slightly higher, namely between 42-50%. It should be noted, however, that these normal values ​​can always fluctuate slightly. There are patients who are completely healthy, although their hematocrit value does not quite correspond to the normal range. One reason for this is that a Normal value only ever includes 95% of all patients and there are always deviations in 5% of the patients, which are completely physiological, on the other hand it can also be that due to one Altitude stay the hematocrit value changes because we produce more erythrocytes at high altitude, which then leads to an increased hematocrit value.

At the same time, it is important to note that a normal hematocrit is not always to be equated with a complete one health. In the so-called normochromic, normocytic anemia it is a form of anemia in which both the Erythrocyte content in the blood and the amount of blood is decreased. This leads to the Hematocrit value seems completely normal, since only that Relationship between erythrocytes and blood volume is specified. However, when both are decreased, the hematocrit remains normal, even though it is a pathological anemia. This can be done, for example high blood loss, for example after an accident. That is why it is always important to always see the hematocrit in context.

High hematocrit

With one too high hematorkit score (over 50% in men and over 45% in women), contains the blood Too many erythrocytes compared to the blood volume, too many oxygen-transporting cells. This is known as Polyglobules.
At the same time, however, it can also be that the number of erythrocytes is normal, but it is one Loss of blood plasma, so blood fluid comes, which then leads to the fact that there are too many cells compared to the blood plasma.

As mentioned earlier, it is particularly important longer stays at high altitude cause the hematocrit value to rise. This is because for the body to stay in height always with one maximum effort connected is. In order to provide the tissue with sufficient oxygen, a increase production of erythropoitin, short EPO, in the kidney. This EPO now stimulates the in the bone marrow Conversion of undifferentiated stem cells to erythrocytes, i.e. to cells that transport more oxygen and thus can better supply the tissues of our body with oxygen.
Especially athlete That is why they like to drive up high mountains with them before competitions without doping and completely physiologically have more oxygen-transporting cells available, which indirectly help the body not to tire so quickly. With such permitted “doping” the Hematocrit value up to 70% increase, and after returning to normal heights, it also drops quickly again.

It is important to know that the increased erythrocytes in the blood cause the blood also more viscous and can no longer flow so quickly. The body can do this to a certain extent with the help of various anticoagulant substances balance, but there is always an increase in the viscosity. This harbors the Thrombus dangerswhich then to Vascular occlusions and in the worst case too Pulmonary embolism and the like. In general, one can say that the hematocrit is always increased when the body is under Lack of oxygen or under Dehydration (Dehydration).

Low hematocrit

One to low hematocrit exists when the value is at Woman under 37% amounts and at Man under 42%. On the one hand, this can be due to the fact that the patient has drunk excessively or has received a fluid replacement (e.g. an NaCl solution) for a long time.
Since there is then an increased blood volume without the same amount of erythrocytes being formed at the same time, the hematocrit is lowered. This does not have to have any pathological consequences, however, it is possible that a hematocrit that is too low on a Anemia (Anemia). This has the positive side effect that that Blood less viscous is, so the viscosity is lowered, but at the same time there is also a poor supply of the tissue With blood and thus with oxygen. Patients with a low hematocrit often suffer from lips turning blue quickly, Fingers and toeswhich also get cold very quickly. A physiologically low hematocrit value is the main factor Endurance athletes in front. It causes the thin blood to put less strain on the blood vessels and the heart, which in turn has a positive effect on health.