Full CBC not always necessary
Only patients with a low hemoglobin value need follow-up with a full blood count. This is the conclusion of a study where 500 blood samples sent for full blood analysis were examined.
The authors of the study, Lewis and Osei-Bimpong, started by testing the blood samples for hemoglobin. Of the 500 samples 405 had normal values. Full blood counts on those samples revealed that only 15 percent had one or more blood count parameter outside two standard deviations (SD) of normal reference values. If the limit was set at three SD, abnormalities were found in only 7.6 percent of the cases. The authors conclusion was that it is only for these 7.6 percent that a full blood count would have contributed significantly to the understanding of the patient’s condition. The most common abnormalities were low mean cell volume (MCV), leucocytosis and leucopenia. These accounted for more than two thirds of the abnormalities. The authors conclude that hemoglobin alone is adequate as a primary screen in general practice. It is only when anemia is detected or when clinical signs and the patient’s history indicate a need for a full blood count that such an investigation is necessary. Following this procedure it is unlikely to miss the diagnosis of any clinically significant condition.
Lewis, S. M. and Osei-Bimpong, A., Clin Lab Haem, 2003, 25; 343-346