Published online July 3, 2006
PEDIATRICS Vol. 118 No. 1 July 2006, pp. 180-188 (doi:10.1542/peds.2005-2475)
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A Randomized, Controlled Trial of the Effects of Adding Vitamin B12 and Folate to Erythropoietin for the Treatment of Anemia of Prematurity

Nadja Haiden, MDa, Katrin Klebermass, MDa, Francesco Cardona, MDa, Jens Schwindt, MDa, Angelika Berger, MDa, Christina Kohlhauser-Vollmuth, MDa, Bernd Jilma, MDb and Arnold Pollak, MDa

a Pediatrics
b Clinical Pharmacology, Medical University of Vienna, Vienna, Austria


   ABSTRACT
TOP
 ABSTRACT
METHODS
 RESULTS
 DISCUSSION
 CONCLUSION
 REFERENCES
 
BACKGROUND. Premature infants, especially those with birth weights of <1500 g, often suffer from anemia of prematurity and associated problems. Erythropoietin therapy is a safe effective way to prevent and to treat anemia of prematurity. We hypothesized that combined administration of vitamin B12 and folate with erythropoietin and iron would enhance erythropoietin-induced erythropoiesis.

METHODS. In a randomized, controlled trial, 64 premature infants (birth weight: 801–1300 g) receiving erythropoietin and iron supplementation were assigned randomly to receive either vitamin B12 (3 µg/kg per day) and folate (100 µg/kg per day) (treatment group) or a lower dose of folate (60 µg/kg per day) (control group).

RESULTS. During the 4-week observation period, vitamin B12 and folate enhanced erythropoietin-induced erythropoiesis significantly, as indicated by a 10% increase in red blood cell counts, compared with folate alone. Hemoglobin and hematocrit levels remained stable in the treatment group, whereas they decreased in the control group. Vitamin B12 levels in the treatment group increased over baseline and control values, whereas red blood cell folate levels were comparable between the groups. Subsequent analysis showed slight nonsignificant differences in baseline red blood cell count, hemoglobin level, hematocrit level, and mean corpuscular volume values, which must be addressed as a limitation.

CONCLUSIONS. With the limitation of a slight imbalance in baseline data between the study groups, combined therapy with vitamin B12, folate, erythropoietin, and orally and intravenously administered iron seemed more effective in stimulating erythropoiesis among premature infants, compared with erythropoietin, iron, and low-dose folate alone. Additional trials are necessary to confirm these data.

Key Words: anemia of prematurity • erythropoietin • folic acid • vitamin B12

Abbreviations: RBC—red blood cell • MCV—mean corpuscular volume • TFR—transferrin receptor

Improved oxygenation after birth results in systemic oxygen delivery that far exceeds oxygen consumption among newborns. Without hypoxic stimuli for erythropoietin production,1 serum erythropoietin concentrations decrease and erythropoiesis declines rapidly.2 A decrease in hemoglobin concentration of 7 to 8 g/dL, which seems to be proportional to the degree of prematurity, occurs commonly among preterm infants who have not undergone significant phlebotomy losses.3 Erythropoietin concentrations among anemic preterm infants are significantly lower than those found for adults with a similar degree of anemia. Infants suffering from anemia of prematurity have a decreased ability to increase serum erythropoietin concentrations, despite a decline in oxygen availability for tissues and the appearance of signs of anemia.4

Among adults, erythropoietin is used for the treatment of anemia associated with renal disease5 or cancer6 and for autologous blood donation before surgery.7 Erythropoietin seems to be safe and effective in the treatment of anemia of prematurity, as evidenced by increased reticulocytosis and increased hematocrit levels.8–10 However, the optimal therapeutic strategy, with respect to dosage, duration, and mode of application of erythropoietin and iron, to stimulate erythropoiesis most efficiently remains controversial. In addition to erythropoietin, several other factors have an impact on the prevention of anemia of prematurity. A sufficient supply of protein, energy, folic acid, and vitamin B12 plays a decisive role in erythropoiesis among premature infants.11–13 In situations of increased erythropoiesis, such as erythropoietin therapy, preterm infants with lower folate stores may become folate deficient14,15 and may require supplementation. In a pilot study,15 erythropoietin in combination with iron and a small amount of folic acid was administered to premature infants with anemia of prematurity. The mean corpuscular volume (MCV) was significantly higher in the erythropoietin group, compared with a control group that received no erythropoietin. The authors speculated that the higher MCV in the erythropoietin group might be attributable to a relative deficiency of folate and vitamin B12. A higher demand for folic acid among infants undergoing erythropoietin therapy was reported by other investigators.16–18 To date, however, only one study has investigated the effect of folic acid in combination with vitamin B12 supplementation on red blood cell (RBC) production among premature infants.19 Worthington-White et al19 showed that additional supply of folic acid (100 µg/kg per day) and vitamin B12 (100 µg/kg per month), exceeding the basic requirements of premature infants, stimulated erythropoiesis, as evidenced by a significantly lesser decline in hemoglobin levels, compared with untreated control subjects. However, the infants in that study did not receive erythropoietin therapy. No data on combined therapy with erythropoietin and iron, folic acid, and vitamin B12 for premature infants are available to date.20

Accordingly, the aim of the current study was to investigate whether therapy with vitamin B12 and folate in combination with erythropoietin might promote erythropoiesis among premature infants. We hypothesized that vitamin B12 and folic acid might enhance erythropoietin-induced erythropoiesis in anemia of prematurity.


   METHODS
TOP
 ABSTRACT
 METHODS
RESULTS
 DISCUSSION
 CONCLUSION
 REFERENCES
 
Study Design and Study Population
The study design was a randomized, controlled trial with 2 treatment arms. Premature infants with birth weights between 801 g and 1300 g and gestational ages of ≤32 weeks who were admitted to the NICUs of the Department of Pediatrics, Medical University of Vienna (Vienna, Austria), were eligible for inclusion in the study. Exclusion criteria were hemolytic disease, maternal causes of neonatal thrombocytopenia, major hemorrhage (defined as intraventricular hemorrhage of grade III or IV21 or gastrointestinal or pulmonary hemorrhage associated with a hemoglobin decrease of >2 g/dL in 24 hours), twin-to-twin transfusion syndrome, major congenital malformations, and known gastrointestinal abnormalities.

Infants were assigned randomly to either vitamin B12 and folate (treatment group) or low-dose folate (control group). Randomization was performed with sealed opaque envelopes. The study was approved by the ethics committee of the University of Vienna. Written consent was given by the parents after full explanation of the procedure.

Study Protocol
Details on study medications in both arms are listed in Table 1 (erythropoietin, Erypo; Janssen-Cilag Pharma, Vienna, Austria; iron dextran, INFeD; Schein Pharmaceutical, Morristown, NJ; iron polymaltose complex, Maltofer; Vifor International, St Gallen, Switzerland; folic acid, Folsan; Solvay Pharma, Klosterneuburg, Austria; vitamin B12, vitamin B12 Lannacher; Lannacher Heilmittel, Lannach, Austria).15,17,19 With the exception of folate, all study medications were administered from the second day of life up to 40 weeks’ gestational age, corrected for prematurity, or until discharge, whichever came first. Folate is available only as an oral preparation, and administration was started on the 15th day of life or when the infant tolerated enteral feeding of 60 mL/kg, whichever came first. Iron dextran and vitamin B12 were added to the parenteral nutrition. Once the infant was receiving full enteral feedings, iron was given enterally and vitamin B12 was administered as a subcutaneous injection. Recommendations for daily parenteral intake are 56 µg/kg for folic acid and 0.3 µg/kg for vitamin B12.11 Infants received this basic supply in an intravenous vitamin supplementation solution (Soluvit; Fresenius AB, Stockholm, Sweden) containing 40 µg/mL folic acid and 0.5 µg/mL vitamin B12, which was added to the parenteral nutrition.


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  		TABLE 1 Therapy Protocol

 
Because erythropoietin was shown to be safe at lower doses, recently there has been a tendency to increase the dose of erythropoietin to increase efficacy.15 Therefore, we decided to administer (intravenously and subcutaneously) consistently higher doses throughout the whole study period. Initial doses were based on birth weight, and doses were adjusted to the current weight twice per week. Criteria for withholding the erythropoietin and iron included neutropenia (neutrophil count of <500 cells per µL) and severe sepsis (defined as culture-proven sepsis requiring catecholamine or ventilatory support). The study drug was restarted when neutrophil counts increased to >500 cells per µL. In cases of severe sepsis, erythropoietin therapy was interrupted for 3 days and then restarted. Iron was not administered parenterally while erythropoietin was being withheld. The primary rationale for withholding study medication was to pause iron treatment during culture-proven sepsis. Iron has been reported to be a growth factor for a number of bacteria and might worsen the patient’s condition during sepsis.22,23 During the study, a strict transfusion protocol, as described by Shannon et al,24 was followed. If the transfusion criteria were fulfilled, then a daily maximum of 15 mL/kg packed RBCs (irradiated, washed, and filtered) was transfused until the infant’s hematocrit level increased to ≥40%. Transfusions were administered only once in 24 hours; packed RBCs were transfused at a rate of 10 mL/kg per hour, over 3 to 4 hours. The next day, the hematocrit level was reevaluated. If hematocrit levels did not exceed 40%, then another transfusion was administered to the patient and documented as a second transfusion. The exact volume of blood transfused, the number of donors, and increases in hematocrit and hemoglobin levels were recorded on the case report form.

Enteral nutritional daily intake of vitamin B12 and folate was calculated separately for each infant. Recommendations for daily enteral intake are 50 µg/kg for folic acid and 0.15 µg/kg for vitamin B12.11 Infants were fed according to a standardized algorithm, by using their mother’s milk (containing 5.2 µg/100 mL folic acid and 0.03 µg/100 mL vitamin B1225) supplemented with a powdered milk fortifier (FM 85, containing no extra folate or vitamin B12; Nestle, Vevey, Switzerland) or a formula for premature infants (for infants weighing <1000 g, 15% Alfare, containing 6.5 µg/100 mL folic acid and 0.16 µg/100 mL vitamin B12; Nestle; for infants weighing >1000 g, Beba F, containing 56 µg/100 mL folic acid and 0.24 µg/100 mL vitamin B12; Nestle).

Blood Sampling and Laboratory Methods
Baseline values for all parameters were obtained from cord blood. For both groups, complete blood counts, differential counts, and reticulocyte counts were measured weekly in samples obtained through venipuncture (usually from a hand or foot vein) or from a central venous line. Levels of folic acid, vitamin B12, ferritin, transferrin receptor (TFR), and iron were measured at baseline and after 4 weeks. Complete blood counts, differential counts, and reticulocyte counts were performed with an automatic blood cell counter (Cell Dyn 4000; Abbott, Vienna, Austria). Ferritin was measured with nephelometry (Beckmann Image; Instrumentation Laboratory, Vienna, Austria), TFR with an enzyme-linked immunoassay method (R&D Systems, Oxon, United Kingdom), iron with a 2-point measurement procedure (Vitros 950; Orthodiagnostic, Assista Laborelektrik, Vienna Austria), vitamin B12 with a micro-part enzyme intrinsic factor system (IMX; Abbott), and RBC folic acid with an iron-capture assay (IMX; Abbott)

Statistical Analyses
On the basis of studies investigating folate and vitamin B12 supplementation for premature infants,19 a sample size estimation26 indicated that 60 infants would allow detection of a 20% difference in the primary end point (ie, hemoglobin levels for the groups), with 80% power and a significance level of .05. Additional analyses were performed with other parameters of the RBC cell line (RBC counts, folate levels in RBCs, hematocrit levels, and MCVs) and vitamin B12 levels, which were defined as secondary outcome parameters.

From chart reviews, we estimated the median study period before transfer to other hospitals to be ~1 month for this patient group. To avoid a high dropout rate and introduction of bias, the study period was limited to 4 weeks.

Results are expressed as the median and interquartile range or as the median and range. Given the non-normal distribution of the data, all comparisons were performed with nonparametric tests. The primary objective was to compare values of outcome parameters between the study groups 4 weeks after the start of treatment. Differences between groups were tested with the Mann-Whitney U test. Differences in values before and after 4 weeks of treatment within the 2 study groups were tested for significance with the Wilcoxon test. Posthoc analyses were performed to consider differences between baseline values. The differences between baseline and treatment values within the groups were calculated and were compared between groups with the Mann-Whitney U test. The {chi}2 test was used to test for differences in clinical characteristics between the study groups. P values of <.05 were considered statistically significant. All calculations were performed with Statistica software (StatSoft, Tulsa, OK).


   RESULTS
TOP
 ABSTRACT
 METHODS
 RESULTS
DISCUSSION
 CONCLUSION
 REFERENCES
 
Study Population
Eighty-eight infants were eligible for enrollment in the study and were recruited between October 2000 and November 2002. Two infants died and 8 were transferred to other hospitals before randomization. Fourteen infants were excluded because of parental refusal (n = 11), trisomy 13 (n = 1), or intraventricular hemorrhage grade IV (n = 2). Thirty-one and 33 infants were assigned randomly to the treatment group and control group, respectively. Demographic features (Table 2) and baseline clinical characteristics (Table 3) were well balanced between the groups. Randomization yielded comparable demographic data (Table 2). No significant differences in nutritional daily intake of vitamin B12 and folate were detected between groups. No adverse events were observed.


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  		TABLE 2 Demographic Characteristics of the Study Population

 

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  		TABLE 3 Clinical Characteristics of the Study Population

 
RBC Parameters, Iron Status, and Transfusion Requirements
RBC counts at baseline were similar for the 2 groups (3700 cells per nL). After initiation of erythropoietin therapy, RBC counts increased rapidly in the treatment group, compared with the control group. At 4 weeks, RBC counts in the treatment group were 10% higher than those in the control group (treatment group: median: 4360 cells per nL; range: 172 cells per nL; control group: median: 3925 cells per nL; range: 174 cells per nL; P = .007) and were also significantly higher than baseline values (P = .04) (Fig 1A). Hemoglobin and hematocrit levels remained stable in the treatment group during the study period, whereas both parameters were significantly lower than baseline values in the control group. At 4 weeks, hemoglobin levels (Fig 1B) and hematocrit levels were significantly higher in the treatment group than in the control group (13% and 15%, respectively; P = .002). In the treatment group, the MCV and mean corpuscular hemoglobin level were transiently higher at week 2 (MCV, P = .02; mean corpuscular hemoglobin level, P = .05) (Fig 1C), whereas the mean corpuscular hemoglobin concentrations did not differ between the groups. In both study groups, MCV was significantly lower at 4 weeks, compared with baseline values (P > .0005). However, randomization yielded slight (insignificant) baseline differences between groups; the control group had a slightly lower mean RBC concentration, hemoglobin concentration, hematocrit level, and MCV at baseline.


Figure 1
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  		FIGURE 1 Effects of vitamin B12 and folate on parameters of the RBC line among premature infants undergoing erythropoietin therapy for treatment of anemia of prematurity. Data are presented as medians for the treatment group (black diamonds; vertical lines indicate upper quartiles) and the control group (white triangles; vertical lines indicate lower quartiles). The x-axis represents the week of life, starting with the sample taken from cord blood at the beginning of the study. RBC counts (A) and hemoglobin levels (B) were significantly higher in the treatment group, compared with the control group (P < .05); MCV (C) was transiently higher at week 2 in the treatment group (P = .02). No differences in reticulocyte counts (D) and RBC distribution width (RDW) (E) were noted between the groups. aP < .05.

 
To consider the differences in starting values, we calculated posthoc differences between baseline and 4-week values within the groups and compared these results between the groups with the Mann-Whitney U test. This analysis provided no significant result; therefore, we cannot exclude the possibility that the results obtained with the absolute values were partly attributable to the baseline differences.

With erythropoietin therapy, reticulocyte counts were high in both groups (between 5.3% and 6.8%), in comparison with baseline values, without any significant difference (Fig 1D). No difference in RBC distribution width was noted between the groups (Fig 1E). There were no differences in iron status, measured as serum levels of iron, ferritin, and TFR and transferrin saturation (Table 4). Because erythropoietin therapy enhances hemoglobin levels, transfusion triggers usually are not reached; therefore, our study was not designed to detect a significant difference in transfusion requirements, which were not different between the groups (Table 5).


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  		TABLE 4 Parameters for Folic Acid, Vitamin B12, and Iron Status

 

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  		TABLE 5 Patients’ Transfusion Requirements

 
Folic Acid in RBCs and Vitamin B12
Serum vitamin B12 levels increased significantly after the 4-week treatment period and were 37% higher in the treatment group, compared with the control group (P = .003) (Table 4). Folate was introduced on day 15 in both the treatment group and control group (range: 2–29 days and 3–22 days, respectively). No significant differences in RBC folic acid concentrations were found between the groups.


   DISCUSSION
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
CONCLUSION
 REFERENCES
 
This study investigated whether high doses of vitamin B12 and folate would enhance the beneficial effect of erythropoietin in the treatment of anemia of prematurity. Our results indicated increases in RBC counts and vitamin B12 levels (Fig 1A and Table 4) and less-pronounced decreases in hemoglobin and hematocrit levels in the treatment group, compared with the control group. However, there were slight differences in baseline RBC concentration, hemoglobin concentration, hematocrit level, and MCV values. Therefore, the possibility that this might have accentuated the differences between groups during treatment cannot be excluded.

Supply of vitamin B12 plus folic acid did not affect MCV, compared with control conditions. During the first weeks of life, a decrease in MCV is described as a physiologic condition among neonates.27 With the 2 different treatment regimens, we expected a faster decline of MCV in the treatment group. This effect could not be observed with the doses of folate and vitamin B12 administered in the present study. MCV declined similarly in the 2 groups, and differences in MCV before and after treatment were highly significant in the 2 groups. It can be hypothesized that the lack of significant difference in MCV between the groups is caused by the fact that supplementation with folic acid at doses of 100 µg/kg per day may still be insufficient under conditions of erythropoietin-enhanced erythropoiesis.

High-dose folate supplementation did not affect significantly folic acid levels in RBCs. During erythropoiesis not stimulated by proerythropoietc drugs, a decrease in folate levels in RBCs seems to be a physiologic phenomenon among premature infants, as indicated by Worthington-White et al.19 Those authors investigated the effects of folate and vitamin B12, applied in combination or as single agents, on various hematologic parameters among premature infants during their first 4 months of life. They observed a decrease in RBC folate levels during the first 4 weeks of life irrespective of supplementation with folate and vitamin B12, in combination or as single drugs, compared with control values. With enhanced erythropoiesis, we expected an increase in RBC folate levels; however, the physiologic decrease seems to predominate with the dose of folate used in our study.

In most of the erythropoietin studies among premature infants, folate was supplemented at doses between 25 µg/kg and 2 mg/kg per day. To the best of our knowledge, only one study reported on RBC folate levels among premature infants undergoing erythropoietin therapy.28 In that study, folate was supplemented at a dose of 200 µg, independent of body weight. The authors found significant differences in RBC folate levels between the erythropoietin and control groups after 4, 6, and 8 weeks of treatment. Remarkably, RBC folate baseline levels were eightfold higher than the values obtained in the present study. However, differences in study design, patient characteristics, and study medications render comparison of the 2 studies impossible.

The most likely explanation for the marginal differences in RBC folic acid levels and MCV in the present study might be attributable to the late start of folate supplementation at approximately the 15th day of life, compared with the initiation of erythropoietin therapy on the second day of life. Because vitamin B12 and folate enhanced erythropoietin-induced erythropoiesis, it is also conceivable that folate stores might have been depleted more quickly.

For reasons of better comparability with previously published data on premature infants, doses of folate supplements were provided according to the study by Worthington-White et al19 for the treatment group and according to center practice for the control group. These doses seem to be safe for premature infants, whereas higher doses have not been well investigated. Only one study of premature infants reported 2-mg folate supplementation during erythropoietin therapy.18 However, this must be analyzed critically in light of the results of a study of healthy adult volunteers ingesting 15 mg of folic acid per day. The study was stopped prematurely after 1 month, when most volunteers experienced weight loss and gastrointestinal, neurologic, and psychological adverse effects.29 Additional trials are needed to assess the efficacy of higher doses of folate in combination with erythropoietin therapy.

Preterm infants have lower folate body stores at birth and higher growth demands, compared with term infants. Almost two thirds of preterm infants experience low serum folate levels between 1 and 3 months of age.14,30 Folic acid supplementation can prevent megaloblastic erythropoiesis among folate-deficient individuals, but the extent to which this translates into increases in hemoglobin concentrations among infants and adults is not known. Currently, folate is available only for the enteral route of administration, at least in Austria. Premature infants often suffer from feeding problems associated with delayed enteral feeding tolerance.31,32 Intolerance of food is accompanied by gastric residuals and, in such cases, enteral feedings are withheld. Therefore, absorption of enterally administered medication is inconsistent and not guaranteed. However, early initiation of folate substitution seems to be essential to avoid the development of megaloblasts during enhanced erythropoiesis.

Reticulocyte counts were stable over 4 weeks in both groups, which can be attributed to erythropoietin. However, we observed a discrepancy of an increase in RBC counts with stable hemoglobin and hematocrit levels in the treatment group. There is evidence from animal33 and human34 studies in the literature that vitamin B12 has an effect on the half-life of erythrocytes. Patients with megaloblastic anemia have a shortened mean cell life, which recovers to a normal life span after substitution of vitamin B12. Therefore, the decreasing RBC counts, hemoglobin levels, and hematocrit levels in the control group can be explained by a shorter erythrocyte life span, attributable to relative vitamin B12 deficiency, among individuals with enhanced erythropoiesis during erythropoietin therapy. This is only speculative, however, because we did not analyze erythrocyte life span.

To date, only one study has investigated the effect of additional supply of folic acid and vitamin B12 on RBC production among premature infants. Additional supplementation of folic acid (100 µg/kg per day) and vitamin B12 (100 µg/kg per month) stimulated erythropoiesis, as evidenced by a significant increase in hemoglobin levels.19 However, the infants in that study did not receive erythropoietin. To the best of our knowledge, no data on combined therapy with erythropoietin and iron, folic acid, and vitamin B12 among premature infants are available.20 The results from the present study indicate that the supportive roles of vitamin B12 and folic acid during enhanced erythropoiesis might have been underestimated to date. Although the baseline imbalance found in our data preclude firm recommendations for clinical practice, it seems important to report these data for the design of similar trials.

The various tests that measure iron status must be interpreted with caution during the first months of life, because they do not necessarily reflect the actual status of the infant’s iron stores.35 Among premature infants, plasma levels of ferritin (a marker for iron storage capacity) decrease with increasing postnatal age.36 Serum levels for ferritin are 6- to 10-fold higher (60–100 µg/L) for infants and adults with erythropoietin-stimulated erythropoiesis, compared with untreated individuals.5,37 However, previous studies that investigated anemia of prematurity showed that, despite iron supplementation, ferritin levels decreased during erythropoietin therapy.38 Our finding that ferritin levels increased during erythropoietin therapy differs from the previously published data. Differences in dosing regimens for erythropoietin and iron and different routes of administration of iron may account for this result (2100 IU/kg per week erythropoietin and 1.5 mg/kg per day intravenously administered iron plus 9 mg/kg per day orally administered iron in the present study, compared with 900 IU/kg per week erythropoietin and 6 mg/kg per day orally administered iron previously38). Because the daily amount of iron used in the present study was higher and the administration route for iron was different, it is conceivable that iron stores, as represented by plasma ferritin levels, were filled more effectively.

TFR levels indicate erythroid TFR expression or iron status when stores are depleted.39,40 An early increase in TFR levels has been shown to predict the erythropoietic response to erythropoietin among both premature infants41 and adults.42 In the present study, the concentration of TFR also increased, which indicates that TFR plasma levels were influenced strongly by erythropoiesis and not by iron nutritional status alone.

The results of this trial demonstrate sufficient supplementation with iron during erythropoietin-stimulated erythropoiesis, as evidenced by increasing ferritin levels, and measurable erythropoietic responses, as evidenced by increasing TFR levels. Among premature infants and among adults, the combination of TFR level, serum ferritin level, and reticulocyte count seems to be predictive of an erythropoietic response to increased erythropoietin doses or increased iron requirements.5

An unfortunate limitation of the study is that, despite randomization, the groups were not ideally balanced with respect to the outcome variables. The control group started with slightly (not significantly) lower RBC counts and hemoglobin and hematocrit concentrations. The possibility that this might have accentuated the differences between groups during treatment cannot be excluded. Another limitation is that the current trial was not designed to detect a difference in the number of infants requiring transfusion. On the basis of the data from this study (Table 5), such a study would require a total of 500 infants ({alpha} = 0.05, ß = 0.8) and thus would require a multicenter trial.


   CONCLUSION
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
 CONCLUSION
REFERENCES
 
With the limitation of a slight imbalance in baseline data between study groups, combined therapy with vitamin B12, folate, erythropoietin, and orally and intravenously administered iron seemed more effective in stimulating erythropoiesis among premature infants than erythropoietin, iron, and low-dose folate alone. Additional trials are necessary to confirm these data.


   FOOTNOTES
 
Accepted Jan 19, 2006.

Address correspondence to Nadja Haiden, MD, Department of Pediatrics, Division of Neonatology, Inborn Errors, and Pediatric Intensive Care, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria. E-mail: nadja.haiden{at}meduniwien.ac.at

The authors have indicated they have no financial relationships relevant to this article to disclose.


   REFERENCES
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 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
 CONCLUSION
 REFERENCES
 

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PEDIATRICS (ISSN 1098-4275). ©2006 by the American Academy of Pediatrics



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