Compared with participants who did not receive iron supplementation , those who received iron supplementation had shortened time to @ % hemoglobin recovery in both the low-ferritin ( mean , @ days , interquartile range -LSB- IQR -RSB- , @-@ , vs @ days , IQR , @ - > @ ) and higher-ferritin groups ( @ days , IQR , @-@ , vs @ days , IQR , @-@ ) .