Sentinel trends in donor hemoglobin values and low‐hemoglobin deferrals in a large <scp>US</scp> blood center

Hemoglobinometer calibration drift, a ferritin testing policy, and donor testosterone use together shaped long-term donor Hb trends. Surveillance of mean donor Hb should be treated as a sentinel metric, and unexpected declines and increases in related deferral rates warrant the same scrutiny to protect both donors and blood availability.