A patient's white blood count comes off an automated cell counter as 380 ´ 109/L. Which of the following could be reported without any additional testing?

a. Red blood count
b. Hemoglobin
c. Hematocrit
d. Platelet count

ANS: D
The platelet count could be reported, but none of the other results are reportable. White cells are always counted with red cells; however, there normally are so few of them in comparison to the number of red cells that their presence does not significantly affect the red count. When the white count is markedly elevated, it significantly affects the red count and MCV and thus the hematocrit. The hemoglobin is also invalid because the high number of white cells adds turbidity to the hemoglobin measurement, thus falsely increasing the hemoglobin determination (and then also the MCH and MCHC). The markedly elevated white cell count necessitates at least a blood film review, if not a manual white cell differential (varies with the instrument limitations).