Strictly speaking, the term “anemia” means “without blood.” In reality, if you are anemic you still have enough blood in your arteries and veins to sustain life, but you either have an insufficient number of red blood cells in your circulation or the cells are unable to carry a normal amount of oxygen. If anemia is severe, it can reduce the delivery of oxygen to your organs and tissues.
Anemia is Not a Single Disorder
Anemia is a catchall term for a number of disorders. “The Merck Manual of Diagnosis and Therapy” classifies the various causes of anemia into three main categories: blood loss, deficient red cell production or excessive red cell destruction. More specifically, red blood cells can be lost due to acute or chronic bleeding, they can be immature or poorly formed due to genetic disorders, bone marrow destruction or deficiencies of vitamins or minerals and they can be destroyed by abnormal immune activity, toxins or infections.
Evaluation for Anemia
When your doctor orders a complete blood count, or CBC, to check the status of your red blood cells, he or she is interested in three specific parameters that will determine whether or not you are anemic. Your total red blood cell count is calculated from the number of corpuscles that are present in a small volume of blood. Your hematocrit, which is determined by spinning a small tube of blood in a centrifuge, is a measure of the volume of your red corpuscles as a percentage of your total blood volume. Hemoglobin content is a measurement of your red cells’ oxygen-carrying capacity. Normal values for these parameters vary with age and gender.
Normal Values
If your hematocrit, hemoglobin concentration and total red blood cell count are all within normal limits, you do not have anemia. Abnormalities in any of these values might prompt further testing. If you are an adult male, your hematocrit should measure 42 percent or more, your minimum hemoglobin concentration should be 14 gm per deciliter and your total red cell count should be greater than 4.5 million cells per liter. For adult women, these values should be 37 percent, 12 gm per deciliter and 4 million cells per liter, respectively. Infants’ normal values change as they grow.
Considerations
Over a dozen common forms of anemia have been identified. The diagnosis of anemia should prompt a search for its cause, for anemia is simply a sign of an underlying disorder. According to “American Family Physician,” asymptomatic anemia is often discovered on a routine examination. Even if your doctor discovers a mild anemia on a CBC that is drawn for other reasons, the cause for your anemia should be investigated. If you are having symptoms that lead you to believe you are anemic, such as fatigue, dizziness or a rapid heartbeat, check with your physician to see if you need testing.
References
- “The Merck Manual of Diagnosis and Therapy, 18th Edition: Approach to the Patient with Anemia”; Mark H. Beers, M.D., Editor-In-Chief; 2006
- “American Family Physician”; Normocytic Anemia; Brill J, Baumgardner D; 2000
