Complete Blood Count

Cold agglutinin disease (CAD) is an autoimmune disorder in which the immune system produces antibodies against the body’s own red blood cells (RBCs). Under cold conditions, these autoantibodies cause red blood cells to clump together and disintegrate.

A laboratory test called a complete blood count can be used to help diagnose CAD.

What is a complete blood count?

A complete blood count is a count of each cell type in the blood, including white blood cells, red blood cells, and platelets. A complete blood count also may be used as a measure of hemoglobin — the protein in red blood cells that carries oxygen.

How is a complete blood count performed?

A complete blood count is carried out on a blood sample collected at a hospital or clinic. Many hospitals can perform this test in-house. A small sample of blood is placed into a machine that automatically counts the number of cells, and determines how many of each cell type is present in the sample.

How can a complete blood count help diagnose CAD?

The complete blood count of a patient with CAD will have fewer red blood cells than normal. Sometimes, patients with CAD will have an increase in reticulocytes, which are an immature form of red blood cells. This is because the body is putting red blood cells into circulation before they have finished maturing (or completely turned into red blood cells) to try to compensate for the lack of mature red blood cells. This condition is called reticulocytosis and will be visible in a complete blood count test.

What happens after the test?

After a doctor receives the results of the complete blood count test, the results will be explained to the patient and, if abnormalities are found, discuss options for treatment.


Last updated: Aug. 14, 2019


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