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.
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, chronicanemias, polycythemia, and/or patients undergoing chemotherapy or radiation therapy.
What does the test result mean? NOTE: This test has no single number that identifies an abnormal result.
Your lab report (see a sample report) should include
a range of numbers (reference range) that identifies what is expected for you based on
your age, sex, and the method used in that laboratory. You can find more information
about expected results at Reference Ranges
and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.
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.
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.
This article was last reviewed on February 5, 2008.
This page was last modified on April 8, 2009.
The review date indicates when the article was last reviewed from beginning to end to ensure that it reflects the most current science. A review may not require any modifications to the article, so the two dates may not always agree.
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