RT Journal Article SR Electronic T1 Frequent blood donors risk iron deficiency JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP cmaj.109-4807 DO 10.1503/cmaj.109-4807 A1 Shuchman, Miriam YR 2014 UL http://www.cmaj.ca/content/early/2014/06/30/cmaj.109-4807.abstract AB