What Is the Connection between Anemia and Hematocrit Levels?

The connection between anemia and hematocrit lies in red blood cell counts and hemoglobin. Hematocrit is the level of red blood cells contained within a sample of blood, expressed in percentages. Comparatively, a low count of red blood cells indicates anemia, which results in low levels of hemoglobin in the blood stream.

Hemoglobin is a protein found in all red blood cells, making up approximately 35% of each cell. Such proteins are responsible for transporting oxygen from the respiratory system to other organs and body systems. If the hematocrit, or concentration of red blood cells, is low, then the body does not have enough hemoglobin available to properly transport oxygen, resulting in anemia. As such, hemoglobin is a primary connecting factor between anemia and hematocrit.

When testing for anemia in humans, medical professionals use a test known as Complete Blood Count (CBC,) which takes a sample of the patient's blood and measures both hemoglobin and hematocrit levels. Using a CBC test, medical professionals can determine the percentage of red blood cells in the body, as well as the concentration of hemoglobin within those red blood cells. A combination of low hematocrit and low hemoglobin results in a diagnosis of anemia.

CBC testing for anemia and hematocrit abnormalities is the same for all patients. What constitutes low hematocrit and a resulting anemic diagnosis, however, varies based on gender and age. For example, newborns have a normal hematocrit range of 55–68%, regardless of gender. Alternatively, adult women who have passed puberty present a normal hematocrit level between 38% and 46%, with 40% considered the average. Adult male patients, on average, have a normal hematocrit around 45%.

To further understand CBC test results for hemoglobin, anemia, and hematocrit, it is necessary to understand the process. Results are determined by centrifuging a blood sample to separate the blood into layers; red blood cells pack together in one layer, while white blood cells pack together in another. By analyzing the size of each layer in relation to the whole, laboratory technicians can determine the approximate concentration of red blood cells. Further testing estimates the approximate size of each red blood cell to determine the level of hemoglobin and if a diagnosis of anemia is warranted.

Causes of anemia vary widely, and can include injuries, kidney disease, malnutrition, arthritis, and medical treatments such as chemotherapy. While anemia and hematocrit are interconnected in terms of getting a diagnosis, hematocrit and hemoglobin tests cannot determine the exact cause of anemia. Instead, once the presence of anemia is determined through CBC testing, medical professionals must investigate further to determine the specific cause of the condition.