Complete Blood Count (CBC)

CBC (Complete Blood Count)

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• If the band was on your arm a long time while the blood sample was taken.
• Taking medicines that can cause low platelet levels. Some examples of the many medicines that cause this include steroids, some antibiotics, thiazide diuretics, chemotherapy medicines, quinidine, and meprobamate (Equanil, Miltown, Meprospan).
• A very high white blood cell count or high levels of a type of fat (triglycerides). These can cause falsely high hemoglobin values.
• Having an enlarged spleen, which may cause a low platelet count (thrombocytopenia) or a low white blood cell count. An enlarged spleen may be caused by certain types of cancer.
• Pregnancy, which normally causes a low RBC value and less often a high WBC value.
• Clumping of platelets in the test tube. This can cause a falsely low platelet count and occurs because of the substance used in the test tube.

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Author:	Jan Nissl, RN, BS	Last Updated: December 4, 2006
Medical Review:	Patrice Burgess, MD - Family Medicine Joseph O'Donnell, MD - Hematology/Oncology
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