Hematocrit or Hct is a laboratory parameter that indicates the percentage of red blood cells, also known as erythrocytes, in your total blood volume, being important to identify and diagnose some situations, such as anemia.
Hematocrit levels may also reflect the amount of hemoglobin present in the red blood cells: when your hematocrit levels are low, it usually indicates that there is a low level of red blood cells or hemoglobin, which may indicate anemia, for example. When it is high, it can indicate poor blood flow, which may be due to severe dehydration, for example.
See how to interpret the reference range of hemoglobin.
Reference range for hematocrit
Hematocrit reference values vary from laboratory to laboratory, but usually the normal levels of the hematocrit are:
- Women: between 35 and 45%. In cases of pregnant women, the reference value is usually between 34 and 47%;
- Men: between 40 and 50%;
- Children from 1 year: between 37 and 44%.
The hematocrit level may vary between laboratories and should be interpreted together with other parameters of the hemogram. When there is a small change in hematocrit levels, it does not necessarily mean you have a health problem and therefore the result must be interpreted by the doctor who requested the exam in order for him to make the diagnosis based on the analysis of the result of all the tests requested and symptoms described by you, so that you can start treatment if necessary.
Why may your hematocrit be low
Low hematocrit levels may indicate:
- Lack or decreased vitamin B12, folic acid or iron;
- Excess hydration.
During pregnancy, low hematocrit levels are usually a sign of anemia, especially if hemoglobin and ferritin are also low. Anemia in pregnancy is normal, however, it can be dangerous for the mother and the baby if not properly treated.
Why may your hematocrit be high
The increase in hematocrit may occur mainly due to the decrease in the amount of water in the blood, with an apparent increase in the amount of red blood cells and hemoglobin, which is a consequence of dehydration. In addition, hematocrit may be increased in lung disease, congenital heart disease, when there is low oxygen in the blood or in cases of polycythemia, in which there is increased production and, consequently, excess of red blood cells.