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Table 3 Effects of iron supplementation on hematologic parameters in low birth weight infants

From: Benefits of Iron supplementation for low birth weight infants: A systematic review

Study Effect No Effect % of ID and/or IDA Conclusion Comments
Hammond et al. 1960[22] Hb, HCT significantly higher in T group by 3 mo; erythrocyte count significantly higher in T group by 5 mo Blood volume, circulating Hb mass 27.3 vs 7.7 % IDA (C vs T) Early iron suppl. accelerates recovery from early IDA 27 % loss to follow up; other vitamins were administrated; BW and hematologic measurements slightly higher in C vs T group
Brozovic et al 1974[23] At 3 mo of age, most infants had low serum iron concentrations, which remained low (6–9 mo) NA > 50 % IDA Iron suppl. was insufficient to prevent IDA in most infants No control group; all infants received vitamin K; some infants received other vitamins
Lundstrom et al. 1977[2] SF, Hb, MCV, TRNSAT significantly higher in T group by 3 mo Reticulocyte count 67 vs 0 % ID (C vs T) LBW infants who do not receive iron suppl. may develop ID by 3 mo of age; 2 mg/kg/d iron is adequate for the prevention of IDA 23 % loss to follow up; after 3 mo of age, an increasing number of C group infants were excluded; SF was higher than normal in C group; iron suppl. given in 2 different forms
Iwai et al. 1986[24] Hb, SF, MCV significantly higher in the formula group by 4 mo RBC, SI, TIBC 86 vs 33 % ID (human milk vs formula) Breast-fed infants have a high risk of ID Infants in formula group had slightly higher BW than those in human milk group; iron status of LBW infants was not evaluated
Hall et al. 1993[25] Hospitalization: plasma ferritin lowest in low iron group
Discharge: plasma ferritin significantly lower in both formula groups 8 wks after discharge; MCV, MCH significantly lower in low iron group
Hb, HCT, reticulocyte, TRN, TRNSAT 27, 69, 76 % IDA (high, low, human milk) Preterm infants receive more benefit from receiving preterm infant formula containing 1.3 mg/kg/d iron vs 0.3 mg/kg/d 44 and 25 % of infants in high and low dose groups dropped out because of prematurity related diseases; 13 % of infants in the human milk group completed the study
Griffin et al. 1999[26] NA Hb 18 vs 27 % ID (A vs B) 0.81-1.17 mg/kg/d iron seems to meet the iron nutritional needs of preterm infants In group C, BW was slightly lower, fewer transfusions were received, and Hb was significantly lower vs A and B; no ferritin data for Group C
Franz et al. 2000[27] NA All markers of iron nutrition 14.7 vs 40.0 % ID (T vs C) Fewer infants in group T received blood transfusion vs group C; early iron suppl. is feasible and safe in LBW infants 34 % loss to follow up; group C tended to have > chronic lung disease and ROP
Friel et al. 2001[28] NA No difference in any hematologic parameters 6.9 vs 13.8 % ID (normal vs high) In terms of cognitive outcome, LBW infants did not benefit from high dose iron No control group
Aggarwal et al. 2005[29] Adjusted Hb higher in T group SF NA Iron suppl. marginally increases Hb in LBW infants 42 % loss to follow up
Miller et al. 2006[30] NA SI, SF, TIBC, sTfR NA Corrected reticulocyte count higher in the T group suggesting improved erythropoiesis Iron suppl. was adjusted by individual iron status; CGA, weight, age at enrollment > in T group
Arnon et al. 2007[31] Hb, reticulocytes, iron, ferritin significantly higher in the 2 wk group at 8 wks Reticulocytes, iron, ferritin at 4 wks of age NA Iron suppl. to preterm infants as early as 2 weeks of age was more beneficial for iron status, than at 4 weeks of age All infants given 25 mg/d oral vitamin E; 35 % loss to follow up
Braekke et al. 2007[33] Iron, TRANSAT significantly increased Ferritin NA Oral iron did not change markers of oxidative stress in LBW infants No control group; all infants received other vitamins, including vitamin E; 15 % loss to follow up; short length of iron administration
Sankar et al. 2009[34] NA SF, HCT, Hb NA Iron suppl. at 2 weeks of age did not improve hematological parameters at 2 mo of age in preterm very LBW infants Iron suppl. group received folic acid and vitamin B12; uncommon iron formulation used
Berglund et al. 2010[35] All indicators of iron status differed significantly between groups in a dose-dependent manner NA 2.7, 0, 9.9 % IDA (T1, T2, C)
9.5, 3.8, 35.8 % ID (T1, T2, C)
Marginally LBW infants had higher risk of ID and IDA, especially those exclusively breastfed; 2 mg/kg/d oral iron significantly improved iron status and reduced IDA risk NA
  1. BW, birth weight; C, control; CGA, corrected gestational age; Hb, Hemoglobin; HCT, hematocrit; ID, iron deficiency; IDA, iron deficiency anemia; LBW, low birth weight; MCV, mean corpuscular volume; mo, month; ROP, retinopathy of prematurity; RBC, red blood cell; SF, serum ferritin; SI, serum iron; sTfR, soluble transferrin receptor; suppl., supplementation; T, iron supplementation group; TIBC, total iron binding capacity; TRN, transferrin; TRNSAT, transferrin saturation; wks, weeks; NA, not available.