Question

If you observed an average of 14 platelets per high power field on a peripheral blood smear prepared from the needle tip and your laboratory allowed correlation between the direct instrument count and the blood smear estimate of 20%, what range would you expect the instrument count to be? Is this platelet estimate within an acceptable reference range?

THIS QUESTION IS IN MCKENZIE: CLINICAL HEMATOLOGY 3 EDITION-Textbook Solutions-Chapter 33-2CP-Check Point 2

Book for Biology/ Medical Lab Technologists

Answer 1

Answer: The traditional method for estimation of platelet count per microliter (uL) is the average number of platelets per high power field multiplied by 20,000.

Therefore, we get

14 X 20,000 = 280,000 platelets per microliter.

Since, correlation factor between direct instrument count and blood smear estimate is 20 %, we get a range of:

280,000 +_ (0.2 X 280,000) i.e., 224,000 to 336,000

The normal range of platelet in human is 150,000 to 450,000. Platelet count more than 450,000 results in thrombocytosis and less than 150,000 cause thrombocytopenia.

YES, the platelet estimate is within acceotable reference range.