Should donors be deferred due to low WBC counts after automated Platelets, Pheresis collections?

A transfusion medicine physician in Kansas reports that his regional blood center monitors blood donors who make automated platelet donations with post-pheresis WBC counts. The reason that they do this monitoring is to comply with the FDA document 'Revised Guideline for the Collection of Platelets,Pheresis. This monitoring occasionally discovers a donor who has repeated low WBC counts. Two case examples are shown below.

Example #1: A 35-year-old Caucasian male became a regular platelet donor since one of his family members was diagnosed with leukemia.  Since becoming a platelet donor he has donated 10 times over 20 weeks.  His baseline WBC count is around 4 K per microLiter.  However, at his last three donations, his post donation WBC count was 2.82 K, 2.93 K, and 2.89 K.

Example #2: A 45-year-old female, long-standing platelet donor donates sporadically, averaging about 10-15 times per year.  Her normal WBC count is around 4 K per microL.  On separate non-consecutive occasions her WBC counts have been 2.91 K, 2.75 K, and 2.95 K.  The first two low counts were separated by 4 months (4 donations in between with post-donation WBC counts > 3.0 K (their arbitrary cut-off) and the last two were separated by one donation and one month.

The inquiring physician wonders if donors, such as those reported above, are being deferred by other centers, merely because their WBC counts are on the low side.  If so, what methods are used to defer these individuals (e.g., letter or personal phone call) and what is the 'message' conveyed (e.g., medical follow-up is recommended).

The following comments have been received.

ADDENDA June 29, 2006

1. A Texas physician reports that his blood center routinely performs pre-procedure CBCs on all plateletpheresis donors and defers donors if their WBC count is less than 3 K per microLiter. They inform each deferred donor of the reason, that the deferral is just for the day, and that they may return another day. The respondent reports that he is unaware of any occasion where a donor had a repeatedly low WBC count was considered for indefinite deferral. He speculates that such donors might have "self-selected" and changed over to whole blood donations. If a donor's pre-procedure WBC is normal, but the post-procedure WBC is slightly low, the respondent has not worried about that situation too much, other than to look at the procedure records and make sure nothing out of the ordinary occurred.

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