Hematocrit

Hematocrit refers to the proportion of red blood cells (RBCs), also known as erythrocytes, in relation to the total blood volume. This measurement is crucial for evaluating the body's overall health status and potential hematological disorders. Hematocrit levels are typically assessed as part of a complete blood count (CBC).

Separator for hematocrit 0003

Measurement

The hematocrit value is generally expressed as a percentage. This percentage is determined by dividing the volume of red blood cells by the total volume of blood and multiplying by 100. Hematocrit levels can be affected by the number and size of red blood cells, with factors such as hydration status and nutritional health influencing these parameters. Typically, the hematocrit test is performed on a blood sample taken from a vein, usually in the arm, using a process known as venipuncture.

Blood-centrifugation-scheme

Interpretation of Results

The reference range for hematocrit varies by age, sex, and altitude of residence, with men generally having higher hematocrit levels than women. Abnormal hematocrit levels can indicate various health conditions:

A lower-than-normal hematocrit may suggest anemia, a condition characterized by a reduced number of RBCs or a lower than normal amount of hemoglobin, the oxygen-carrying protein in RBCs. A higher-than-normal hematocrit can indicate dehydration as the volume of plasma decreases while the RBCs remain constant, thus leading to a relative increase in the hematocrit level. It can also be seen in conditions such as polycythemia, where there is an abnormal increase in the production of red blood cells. Certain diseases, such as leukemia and malnutrition, may alter the hematocrit levels due to their impact on red blood cell production.

Clinical Significance

Monitoring hematocrit levels can provide important information about a person's health status. In clinical settings, hematocrit is often used to guide therapeutic decisions, such as the need for a blood transfusion. It can also help monitor response to treatment in conditions affecting red blood cell count or size.

See Also

• Hemoglobin
• Anemia
• Red blood cell indices
• Polycythemia

External links

MedlinePlus Medical Encyclopedia: Hematocrit