Review of full blood count reference interval using a large cohort of first-time plasmapheresis blood donors.

Full blood counts (FBC) are routinely performed on blood donors donating by apheresis. Australian Red Cross Lifeblood (Lifeblood) historically set FBC reference intervals (RIs) in alignment with standards of the Royal College of Pathologists of Australasia (RCPA). Recommendations now advise that RIs be developed locally to represent the population. This study analysed new blood donors' FBC results to inform a review of the current Lifeblood RIs. Retrospective analysis of routine laboratory data for first-time direct to plasmapheresis donations from 1 July 2018 to 30 June 2019 was conducted (n=15,710). FBC were performed using DxH 800 Haematology analysers. The 2.5% and 97.5% percentiles were compared with the current RIs and clinically significant variation informed adjustment. White blood cell and platelet parameters remained in alignment with RCPA reference intervals. The haemoglobin (Hb) RI for female donors reduced from 115-165 g/L to 113-147 g/L. For male donors, the upper limit for Hb required reduction from 185 g/L to 165 g/L. Red blood cell (RBC) counts and haematocrit (HCT) levels were lowered in this derivation from blood donors. Appropriate RIs allow for both the early detection of disease and avoid unnecessary investigation of otherwise healthy people. FBC analysis from current blood donors indicated changes were required to the RIs. The adjusted lower RBC and HCT values reduces the proportion of donors considered to have abnormal findings. The lower Hb limits will remain at 115 g/L in females and 125 g/L in males to align with regulatory requirements for blood donation.