The mean baseline hemoglobin levels were comparable in the iron and no-iron groups and declined from a mean ( SD ) of 13.4 ( 1.1 ) g/dL to 12.0 ( 1.2 ) g/dL after donation in the low-ferritin group and from 14.2 ( 1.1 ) g/dL to 12.9 ( 1.2 ) g/dL in the higher-ferritin group .