Hematocrit
and Eva Rudolf-Müller, doctorDr. med. Andrea Reiter is a freelance writer for the medical editorial team.
More about the expertsEva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.
More about the experts All content is checked by medical journalists.The hematocrit describes the proportion of blood cells in the whole blood and therefore the ability of the blood to flow. It is given in percent. If the amount of fluid in the blood drops, the hematocrit rises. The blood becomes thicker and flows more slowly. This increases the risk of thrombosis and stroke. Read everything you need to know about hematocrit, when to determine it and what it means.
What is hematocrit?
The hematocrit describes the proportion of all solid blood components in the whole blood: This includes the red and white blood cells (erythrocytes and leukocytes) and the blood platelets (thrombocytes). The hematocrit is a measure of the viscosity of the blood:
If the amount of fluid in the blood drops, for example due to profuse sweating, diarrhea or insufficient fluid intake, the hematocrit rises. The blood becomes more viscous. Colloquially it is also said that the blood is “too thick”. Since it no longer flows through the blood vessels as quickly, there is a risk of a blood clot (thrombus) forming, which blocks the vessel. The heart has to use more force to pump the tough blood through the organism.
On the other hand, the hematocrit is lowered if the blood is too “thin”.
When is the hematocrit value determined?
The hematocrit is shown as part of a routine blood test in what is known as a “small blood count”. It provides initial information about the condition of the blood and the water balance of the patient.
The hematocrit value is given in percent. It can either be calculated in a blood cell counter or determined by centrifugation of the blood sample. The red blood cells settle at the bottom of the centrifuge tube. Their share is then measured.
Normal hematocrit values
The normal hematocrit values (in percent) are based on age and gender:
|
age |
Female |
masculine |
|
up to 2 weeks |
39,6 - 57,2 % |
39,8 - 53,6 % |
|
3 to 4 weeks |
32,0 - 44,5 % |
30,5 - 45,0 % |
|
1 month |
27,7 - 35,1 % |
26,8 - 37,5 % |
|
2 to 5 months |
29,5 - 37,1 % |
28,6 - 37,2 % |
|
6 to 24 months
|
30,9 - 37,9 % |
30,8 - 37,8 % |
|
2 to 5 years |
31,2 - 37,8 % |
31,0 - 37,7 % |
|
6 to 11 years |
32,4 - 39,5 % |
32,2 - 39,8 % |
|
12 to 15 years |
33,4 - 40,4 % |
33,9 - 43,5 % |
|
from 16 years |
36,6 - 44,0 % |
40,0 - 49,5 % |
When is the hematocrit level lowered?
If the hematocrit is too low, this could be due to one of the following:
- Anemia
- Overwatering
- Blood loss
When is the hematocrit increased?
If the hematocrit is too high, the following causes are possible:
- dehydration
- Polyglobules (there are too many red blood cells in the blood)
- Polycythemia vera (overproduction of erythrocytes, leukocytes and platelets in the bone marrow)
What to do if the hematocrit value is increased or decreased?
If an increased hematocrit was found in a laboratory test, you should drink enough to increase the fluid content of the blood. If the high hematocrit value can be traced back to an overproduction of cells, further investigations must follow. If necessary, a so-called "bloodletting" is carried out. This involves draining blood through a needle in a vein. This measure can lower the hematocrit quickly and with few side effects.
If the hematocrit is low due to anemia, the doctor will treat it depending on the cause. However, overhydration can also be the reason if the hematocrit is low, for example as a result of excessive drinking of water. The hematocrit then usually rises again on its own over time.
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