Red Blood Cell Count
Also known as: RBC count; Erythrocyte count; Red count
Formal name: Red Blood Cell Count
Related tests: Complete blood count; Blood smear
The Test
How is it used?
A RBC count is used to evaluate any type of decrease or increase in the number of red blood cells as measured per liter of blood. These changes must be interpreted in conjunction with other parameters, such as hemoglobin, hematocrit, and/or red blood cell indicies.
When is it ordered?
A RBC count is ordered as a part of the complete blood count (CBC), often as part of a routine physical, pre-surgical procedure, or for other clinical reasons. The test is also repeated in patients who have hematologic disorders, bleeding problems, chronic anemias, polycythemia, and/or patients undergoing chemotherapy or radiation therapy.
What does the test result mean?
A decreased number of RBCs results from either acute or chronic blood loss. Acute blood loss is a rapid depletion of blood volume. Chronic blood loss stems from various conditions that often results in some form of an anemia. Chronic anemias are due to loss of small amounts of blood over a long period of time (bleeding), mechanical destruction of the RBCs, or some physiologic problem such as decreased RBC production. Increased number of RBCs can result from a number of conditions that include dehydration, congenital heart disease, pulmonary diseases, and situations involving tissue hypoxia.
Trauma
Burns
Pregnancy
Hemolytic anemia
Hemorrhagic infections
Gastrointestinal (GI) or other vascular bleed
Iron deficiency anemia
Vitamin B12 or folate deficiency
bone marrow damage
Metabolic disorders
Chronic inflammation
Dehydration
Pulmonary disease
Congenital heart disease
Polycythemia vera
Renal problems
Over-transfusion of whole blood
Tissue hypoxia
The list below includes some of these conditions.
Decreased RBC
Increased RBC
Is there anything else I should know?
Alteration of the number of RBCs is often transient and can be easily corrected and/or return to normal levels by eliminating the causative agent. Decreases in red blood cells are normally seen during pregnancy as a result of body fluid increases that dilute them.
Living at high altitudes causes an increase in RBC counts; this is your body's response to the decreased oxygen available at these heights.
Drugs that may increase RBC levels include gentamicin and methyldopa.
