title: Season and time of day affect capillary blood hemoglobin level and low hemoglobin deferral in blood donors: analysis in a national blood bank.
abstract: Low hemoglobin (Hb) is the most common reason for temporary blood donor deferral. However, factors that affect Hb measurement may not portray donor health but reflect external circumstances.
  
  
  
  The effects of season, time of day, donor age, ABO, and D on capillary blood Hb level (cHb) and low Hb deferral were analyzed in 1,396,645 donor registrations from the years 2010 to 2014 in a national blood bank.
  
  
  
  cHb was lower in the summer (July mean 154.1 g/L in men, 139.6 g/L in women) and in the evening (7 pm mean 153.8 g/L in men, 138.9 g/L in women) than in the winter (January mean 156.9 g/L in men, 141.8 g/L in women) and in the morning (11 am mean 157.2 g/L in men, 142.8 g/L in women; all p < 0.0001). This affected donor deferral due to low Hb, with 7.8% donors deferred in July at 7 pm and 1.6% deferred in January at 11 am (p < 0.0001). With age, cHb increased in women and decreased in men. The lowest cHb was observed in blood group A (mean 154.9 g/L in men, 140.3 g/L in women) and the highest in blood group B (mean 156.6 g/L in men, 141.5 g/L in women). D had no practically significant effect on cHb.
  
  
  
  External factors, which do not reflect donor health, affect cHb and donor deferral due to low Hb. These factors should be considered when donor eligibility guidelines and procedures are developed.
authors.affiliation: Finnish Red Cross Blood Service, Helsinki, Finland.
authors.forename: Sari
authors.initials: S
authors.lastname: Bäckman
authors.affiliation: Finnish Red Cross Blood Service, Helsinki, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Larjo
authors.affiliation: Finnish Red Cross Blood Service, Helsinki, Finland.
authors.forename: Juha
authors.initials: J
authors.lastname: Soikkeli
authors.affiliation: Finnish Red Cross Blood Service, Helsinki, Finland.
authors.forename: Johanna
authors.initials: J
authors.lastname: Castrén
authors.affiliation: Finnish Red Cross Blood Service, Helsinki, Finland.
authors.forename: Jarkko
authors.initials: J
authors.lastname: Ihalainen
authors.affiliation: Finnish Red Cross Blood Service, Helsinki, Finland.
authors.forename: Martti
authors.initials: M
authors.lastname: Syrjälä
mesh_terms: D000017:ABO Blood-Group System; D000293:Adolescent; D000328:Adult; D000368:Aged; D001771:Blood Banks; D001782:Blood Donors; D001789:Blood Group Antigens; D002196:Capillaries; D002940:Circadian Rhythm; D046148:Donor Selection / Q000379:methods; D005260:Female; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012621:Seasons; D055815:Young Adult
chemical_list: D000017:ABO Blood-Group System; D001789:Blood Group Antigens; D006454:Hemoglobins