At the Edge

Retirement has afforded me more flexibility in donating platelets.  While working, I typically appeared at the Blood Bank quarterly on a Saturday morning.  Now I can come anytime, though I won't accept an afternoon appointment.  And in deference to those still limited to weekends, I opt for a traditional workday for my donation.  Four a year has increased to about ten, or at least that has been my intent.  While the occupational threats to eligibility, usually blood or needle exposure, a new one has emerged, my optimal health.  Once I have been disqualified based on Hb < 13 g/dl on their tabletop hemocytometer.  More typically I come out right at the cutoff.  Since protocol takes the higher of two measurements, I squeak by more often than not. At my most recent donation, test 1 =12,9, test 2 =13.1.  Had it been the reverse, there would only have been one measurement.  It has varied by as much as 0.4 but nobody can tell me the reliability of their desktop instrument. I have been able to predict by how big a drop of blood the technician obtains, so I think a very thin smear wicked into the collector registers low. There is at least one article suggesting that the wicking method overestimates the value obtained on a lab analyzer https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5754049/  In any case, the arbitrary cutoff seems less than medically rigorous if a person can qualify with discrepant results within the sensitivity of the machine.

I asked about temperature.  Temperature is taken by a cutaneous forehead device before they even let a person sign in, a very crude screening but quick and easy to avoid obvious covid concerns.  The formal temperature is sublingual with what I presume is a thermocouple, which would be very accurate.  It surprised me that anyone would show up with a fever until they advised me that their cutoff was 99.6F = 37.6C which is less than medical significance and could easily escape self-detection.

I do not know if there are bp or p cutoffs.  

While it's critical that blood donation be safe for donor and recipient, I wonder to what extent the chronic difficulty recruiting donors reflects some of their own stringencies, some of which seem questionable.  Binary standards, either you're in  or you're out, make screening more automated but at the expense of the blood supply perhaps.  Some things have enhanced eligibility.  Improvements in screening for certain infections have reduced exclusion times from one year to three months for many conditions.  NSAIDS other than Feldene are now permitted for platelet donors.  Yet they really have to err on the side of safety, even when eligibility can shift in literally one minute for the same donor.