Hematocrit is the percentage by volume of red blood cells (RBCs) in your blood. It reflects how much of your blood is made up of red cells as opposed to plasma and other components like white blood cells and platelets

. Red blood cells are crucial because they carry oxygen from the lungs to the rest of the body. Therefore, the hematocrit level is an important indicator of your blood's capacity to transport oxygen

. Normal hematocrit values vary by age and sex:

• For adult men, normal levels range approximately from 41% to 50%.
• For adult women, normal levels range roughly from 36% to 44%

A hematocrit level that is too low may indicate anemia (a deficiency of red blood cells), while a level that is too high may suggest conditions like polycythemia (excess red blood cells) or dehydration

. The hematocrit test is commonly done as part of a complete blood count (CBC) to help diagnose or monitor these and other blood-related conditions

. In summary, hematocrit is a key blood measurement that shows the proportion of red blood cells in blood, helping assess oxygen delivery capacity and detect various health issues.