Erythropoietin (Epo), protein and iron supplementation and the prevention of anaemia of prematurity: effects on serum immunoreactive Epo, growth and protein and iron metabolism

Survey on clinical use and non-use of recombinant human erythropoietin in European neonatal units

Objectives Recombinant human erythropoietin (rhEPO) has been shown to effectively and safely prevent the anemia of prematurity and to reduce the transfusion need in very low birth weight (VLBW) infants and has been licensed for this indication in Europe in 1997. The objective of the study was to obtain information on the use or non-use of rhEPO in neonatal units in Germany and other European countries. Methods Anonymized 14-questions web-based questionnaire. Results Seventy-nine questionnaires from Germany and 63 questionnaires from other 15 European countries were completed. Of the responders, 39% indicated to use rhEPO routinely or occasionally in VLBW infants, whereas 61% responded to never use rhEPO in this population. The major reasons given for non-use were lack of recommendation in national guidelines (69%) and/or doubt about efficacy of rhEPO to reduce transfusion need (53%). Twenty-seven percent of the responders indicated to use rhEPO for neonates with birth weights above 1,500 g. Neuroprotection in VLBW infants (26%) and hypoxic ischemic encephalopathy in term neonates (27%) were given as indications for off label use of rhEPO. Conclusions This survey indicates that rhEPO is used for the anemia of prematurity as licensed in less than half of neonatal units in Germany and other European countries. On the other hand it seems to be used off label in neonates for neuroprotection in a considerable number of units although there is no final evidence on its neuroprotective effects.

Late erythropoiesis-stimulating agents to prevent red blood cell transfusion in preterm or low birth weight infants

BACKGROUND

Preterm infants have low plasma levels of erythropoietin (EPO), providing a rationale for the use of erythropoiesis-stimulating agents (ESAs) to prevent or treat anaemia. Darbepoetin (Darbe) and EPO are currently available ESAs.

OBJECTIVES

To assess the effectiveness and safety of late initiation of ESAs, between eight and 28 days after birth, in reducing the use of red blood cell (RBC) transfusions in preterm or low birth weight infants.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL 2018, Issue 5), MEDLINE via PubMed (1966 to 5 June 2018), Embase (1980 to 5 June 2018), and CINAHL (1982 to 5 June 2018). We searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials of late initiation of EPO treatment (started at ≥ eight days of age) versus placebo or no intervention in preterm (< 37 weeks) or low birth weight (< 2500 grams) neonates.

DATA COLLECTION AND ANALYSIS

We performed data collection and analyses in accordance with the methods of the Cochrane Neonatal Review Group. We used the GRADE approach to assess the quality of the evidence.

MAIN RESULTS

We include 31 studies (32 comparisons) randomising 1651 preterm infants. Literature searches in 2018 identified one new study for inclusion. No new on-going trials were identified and no studies used darbepoetin. Most included trials were of small sample size. The meta-analysis showed a significant effect on the use of one or more RBC transfusions (21 studies (n = 1202); typical risk ratio (RR) 0.72, 95% confidence interval (CI) 0.65 to 0.79; typical risk difference (RD) -0.17, 95% CI -0.22 to -0.12; typical number needed to treat for an additional beneficial outcome (NNTB) 6, 95% CI 5 to 8). There was moderate heterogeneity for this outcome (RR I² = 66%; RD I² = 58%). The quality of the evidence was very low. We obtained similar results in secondary analyses based on different combinations of high/low doses of EPO and iron supplementation. There was no significant reduction in the total volume (mL/kg) of blood transfused per infant (typical mean difference (MD) -1.6 mL/kg, 95% CI -5.8 to 2.6); 5 studies, 197 infants). There was high heterogeneity for this outcome (I² = 92%). There was a significant reduction in the number of transfusions per infant (11 studies enrolling 817 infants; typical MD -0.22, 95% CI -0.38 to -0.06). There was high heterogeneity for this outcome (I² = 94%). Three studies including 404 infants reported on retinopathy of prematurity (ROP) (all stages or stage not reported), with a typical RR 1.27 (95% CI 0.99 to 1.64) and a typical RD of 0.09 (95% CI -0.00 to 0.18). There was high heterogeneity for this outcome for both RR (I² = 83%) and RD (I² = 82%). The quality of the evidence was very low.Three trials enrolling 442 infants reported on ROP (stage ≥ 3). The typical RR was 1.73 (95% CI 0.92 to 3.24) and the typical RD was 0.05 (95% CI -0.01 to 0.10). There was no heterogeneity for this outcome for RR (I² = 18%) but high heterogeneity for RD (I² = 79%). The quality of the evidence was very low.There were no significant differences in other clinical outcomes including mortality and necrotising enterocolitis. For the outcomes of mortality and necrotising enterocolitis, the quality of the evidence was moderate. Long-term neurodevelopmental outcomes were not reported.

AUTHORS' CONCLUSIONS

Late administration of EPO reduces the use of one or more RBC transfusions, the number of RBC transfusions per infant (< 1 transfusion per infant) but not the total volume (mL/kg) of RBCs transfused per infant. Any donor exposure is likely not avoided as most studies included infants who had received RBC transfusions prior to trial entry. Late EPO does not significantly reduce or increase any clinically important adverse outcomes except for a trend in increased risk for ROP. Further research of the use of late EPO treatment, to prevent donor exposure, is not indicated. Research efforts should focus on limiting donor exposure during the first few days of life in sick neonates, when RBC requirements are most likely to be required and cannot be prevented by late EPO treatment. The use of satellite packs (dividing one unit of donor blood into many smaller aliquots) may reduce donor exposure.

Late erythropoiesis-stimulating agents to prevent red blood cell transfusion in preterm or low birth weight infants

BACKGROUND

Preterm infants have low plasma levels of erythropoietin (EPO), providing a rationale for the use of erythropoiesis-stimulating agents (ESAs) to prevent or treat anaemia. Darbepoetin (Darbe) and EPO are currently available ESAs.

OBJECTIVES

To assess the effectiveness and safety of late initiation of ESAs, between eight and 28 days after birth, in reducing the use of red blood cell (RBC) transfusions in preterm or low birth weight infants.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL 2018, Issue 5), MEDLINE via PubMed (1966 to 5 June 2018), Embase (1980 to 5 June 2018), and CINAHL (1982 to 5 June 2018). We searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials of late initiation of EPO treatment (started at ≥ eight days of age) versus placebo or no intervention in preterm (< 37 weeks) or low birth weight (< 2500 grams) neonates.

DATA COLLECTION AND ANALYSIS

We performed data collection and analyses in accordance with the methods of the Cochrane Neonatal Review Group. We used the GRADE approach to assess the quality of the evidence.

MAIN RESULTS

We include 31 studies (32 comparisons) randomising 1651 preterm infants. Literature searches in 2018 identified one new study for inclusion. No new on-going trials were identified and no studies used darbepoetin.Most included trials were of small sample size. The meta-analysis showed a significant effect on the use of one or more RBC transfusions (21 studies (n = 1202); typical risk ratio (RR) 0.72, 95% confidence interval (CI) 0.65 to 0.79; typical risk difference (RD) -0.17, 95% CI -0.22 to -0.12; typical number needed to treat for an additional beneficial outcome (NNTB) 6, 95% CI 5 to 8). There was moderate heterogeneity for this outcome (RR I² = 66%; RD I² = 58%). The quality of the evidence was very low. We obtained similar results in secondary analyses based on different combinations of high/low doses of EPO and iron supplementation. There was no significant reduction in the total volume (mL/kg) of blood transfused per infant (typical mean difference (MD) -1.6 mL/kg, 95% CI -5.8 to 2.6); 5 studies, 197 infants). There was high heterogeneity for this outcome (I² = 92%). There was a significant reduction in the number of transfusions per infant (11 studies enrolling 817 infants; typical MD -0.22, 95% CI -0.38 to -0.06). There was high heterogeneity for this outcome (I² = 94%).Three studies including 404 infants reported on retinopathy of prematurity (ROP) (all stages or stage not reported), with a typical RR 1.27 (95% CI 0.99 to 1.64) and a typical RD of 0.09 (95% CI -0.00 to 0.18). There was high heterogeneity for this outcome for both RR (I² = 83%) and RD (I² = 82%). The quality of the evidence was very low.Three trials enrolling 442 infants reported on ROP (stage ≥ 3). The typical RR was 1.73 (95% CI 0.92 to 3.24) and the typical RD was 0.05 (95% CI -0.01 to 0.10). There was no heterogeneity for this outcome for RR (I² = 18%) but high heterogeneity for RD (I² = 79%). The quality of the evidence was very low.There were no significant differences in other clinical outcomes including mortality and necrotising enterocolitis. For the outcomes of mortality and necrotising enterocolitis, the quality of the evidence was moderate. Long-term neurodevelopmental outcomes were not reported.

AUTHORS' CONCLUSIONS

Late administration of EPO reduces the use of one or more RBC transfusions, the number of RBC transfusions per infant (< 1 transfusion per infant) but not the total volume (mL/kg) of RBCs transfused per infant. Any donor exposure is likely not avoided as most studies included infants who had received RBC transfusions prior to trial entry. Late EPO does not significantly reduce or increase any clinically important adverse outcomes except for a trend in increased risk for ROP. Further research of the use of late EPO treatment, to prevent donor exposure, is not indicated. Research efforts should focus on limiting donor exposure during the first few days of life in sick neonates, when RBC requirements are most likely to be required and cannot be prevented by late EPO treatment. The use of satellite packs (dividing one unit of donor blood into many smaller aliquots) may reduce donor exposure.

Late erythropoietin for preventing red blood cell transfusion in preterm and/or low birth weight infants

BACKGROUND

Low plasma levels of erythropoietin (EPO) in preterm infants provide a rationale for the use of EPO to prevent or treat anaemia.

OBJECTIVES

To assess the effectiveness and safety of late initiation of erythropoietin (EPO) between eight and 28 days after birth, in reducing the use of red blood cell (RBC) transfusions in preterm and/or low birth weight infants.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and CINAHL in July 2013. Additional searches included the Pediatric Academic Societies Annual Meetings from 2000 to 2013 (Abstracts2View™) and clinical trials registries (www.clinicaltrials.gov; www.controlled-trials.com; and who.int/ictrp/en). For this update we moved one study from the early EPO review to this late EPO review.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials of late initiation of EPO treatment (started at ≥ eight days of age) versus placebo or no intervention in preterm (< 37 weeks) and/or low birth weight (< 2500 g) neonates.

DATA COLLECTION AND ANALYSIS

We performed data collection and analyses in accordance with the methods of the Cochrane Neonatal Review Group.

MAIN RESULTS

We include 30 studies (31 comparisons) randomising 1591 preterm infants. Literature searches in 2013 did not identify any new study for inclusion. For this update we moved one study enrolling 230 infants from the early EPO review to this late EPO review.Most included trials were of small sample size. The meta-analysis showed a significant effect of the use of one or more RBC transfusions (20 studies (n = 1142); typical risk ratio (RR) 0.71, 95% confidence interval (CI) 0.64 to 0.79; typical risk difference (RD) -0.17, 95% CI -0.22 to -0.12; typical number needed to treat for an additional beneficial outcome (NNTB) 6, 95% CI 5 to 8). There was moderate heterogeneity for this outcome (RR I² = 68%; RD I² = 60%). We obtained similar results in secondary analyses based on different combinations of high/low doses of EPO and iron supplementation. There was no significant reduction in the total volume (mL/kg) of blood transfused per infant [typical mean difference (MD) -1.6 mL/kg, 95% CI -5.8 to 2.6); 5 studies, 197 infants]. There was high heterogeneity for this outcome (I² = 92%). There was a significant reduction in the number of transfusions per infant (11 studies enrolling 817 infants; typical MD -0.22, 95% CI -0.38 to -0.06). There was high heterogeneity for this outcome (I² = 94%).Three studies including 404 infants reported on retinopathy of prematurity (ROP) (all stages or stage not reported), with a typical RR 1.27 (95% CI 0.99 to 1.64) and a typical RD of 0.09 (95% CI -0.00 to 0.18). There was high heterogeneity for this outcome for both RR (I² = 83%) and RD (I² = 82%). Three trials enrolling 442 infants reported on ROP (stage ≥ 3). The typical RR was 1.73 (95% CI 0.92 to 3.24) and the typical RD was 0.05 (95% CI -0.01 to 0.10). There was minimal heterogeneity for this outcome for RR (I² = 18%) but high heterogeneity for RD (I² = 79%). There were no significant differences in other clinical outcomes. There was no reduction in necrotizing enterocolitis in spite of a reduction in the use of RBC transfusions. Long-term neurodevelopmental outcomes were not reported.

AUTHORS' CONCLUSIONS

Late administration of EPO reduces the use of one or more RBC transfusions, the number of RBC transfusions per infant (< 1 transfusion per infant) but not the total volume (ml/kg) of RBCs transfused per infant. Any donor exposure is likely not avoided as most studies included infants who had received RBC transfusions prior to trial entry. Late EPO does not significantly reduce or increase any clinically important adverse outcomes except for a trend in increased risk for ROP. Further research of the use of late EPO treatment to prevent donor exposure is not indicated. Research efforts should focus on limiting donor exposure during the first few days of life in sick neonates, when RBC requirements are most likely to be required and cannot be prevented by late EPO treatment. The use of satellite packs (dividing one unit of donor blood into many smaller aliquots) may reduce donor exposure.

Late erythropoietin for preventing red blood cell transfusion in preterm and/or low birth weight infants

BACKGROUND

Low plasma levels of erythropoietin (EPO) in preterm infants provide a rationale for the use of EPO to prevent or treat anaemia.

OBJECTIVES

To assess the effectiveness and safety of late initiation of EPO (initiated at eight days after birth or later) in reducing the use of red blood cell (RBC) transfusions in preterm and/or low birth weight infants.

SEARCH METHODS

For this update MEDLINE, EMBASE, CINAHL, and The Cochrane Library were searched in March 2012. Additional searches included the Pediatric Academic Societies Annual Meetings from 2000 to 2012 (Abstracts2 View(TM)) and clinical trials registries (clinicaltrials.gov; controlled-trials.com; and who.int/ictrp).

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials of late initiation of EPO treatment (started at ≥ eight days of age) versus placebo or no intervention in preterm (< 37 weeks) and/or low birth weight (< 2500 g) neonates.

DATA COLLECTION AND ANALYSIS

Data collection and analyses were performed in accordance with the methods of the Cochrane Neonatal Review Group.

MAIN RESULTS

In this 2012 update one new study for inclusion was identified. Twenty-eight studies enrolling 1361 preterm infants in 21 countries were included. Most trials were of small sample size. The meta-analysis showed a significant effect on the use of one or more RBC transfusions [typical risk ratio (RR); 0.66 (95% confidence interval (CI); 0.59 to 0.74); typical risk difference (RD) -0.21 (95% CI; -0.26 to -0.16); typical number needed to benefit (NNTB) of 5 (95% CI 4 to 6) 19 studies, 912 infants]. There was moderate heterogeneity for this outcome [for RR (P < 0.00001; I(2) = 74.0%); for RD (P = 0.0006; I(2) = 58.9%)]. Similar results were obtained in secondary analyses based on different combinations of high/low doses of EPO and iron supplementation. In this update there was no significant reduction in the total volume (mL/kg) of blood transfused per infant [typical MD -1.61mL/kg (95% CI -5.78 to 2.57); 5 studies, 197 infants] There was high heterogeneity for this outcome (P = 0.00001, I(2) = 92%). There was a significant reduction in the number of transfusions per infant (nine studies enrolling 567 infants); [typical MD -0.78 (-0.97 to -0.59)]. Three studies including 331 patients reported on retinopathy of prematurity (ROP) (all stages), with a typical RR 0.79 (95% CI 0.57 to 1.10) and a typical RD of -0.05 (95% CI -0.13 to 0.02). This outcome was not statistically significantly different between the groups. There was no heterogeneity for this outcome for either RR (P = 0.41; I(2) = 0%) or RD (P = 0.43; I(2) = 0%). Two trials enrolling 212 patients reported on severe ROP (stage 3 or greater). The typical RR was 0.83 (95% CI 0.23 to 2.98) and the typical RD was -0.01 (95% CI -0.06 to 0.05); neither were statistically significant. There was no heterogeneity for this outcome for either RR (P = 0.29; I(2) = 9.3%) or RD (P = 0.36; I(2) = 0%).There were no significant differences in other clinical outcomes. Long-term neurodevelopmental outcomes were not reported.

AUTHORS' CONCLUSIONS

Late administration of EPO reduces the use of one or more RBC transfusions, the number of RBC transfusions per infant but not the total volume of RBCs transfused per infant. Any donor exposure is likely not avoided as most studies included infants who had received RBC transfusions prior to trial entry. Late EPO does not significantly reduce or increase any clinically important adverse outcomes. Further research of the use of late EPO treatment to prevent donor exposure is not indicated. Research efforts should focus on limiting donor exposure during the first few days of life in sick neonates, when RBC requirements are most likely to be required and cannot be prevented by late EPO treatment.

Effects of erythropoietin on erythrocyte deformability in non-transfused preterm infants

AIM

Suppression of erythropoiesis due to low plasma erythropoietin levels is an important factor in the development of anaemia of prematurity. Premature infants may therefore be treated with recombinant human erythropoietin (rhEPO). This prospective, randomised and controlled study was designed to find out whether rhEPO treatment improves erythrocyte deformability in preterm infants.

METHODS

Sixteen infants were treated with rhEPO (250 IU/kg three times weekly) a total of 15 times beginning on day of life 5 whereas fifteen infants served as controls. Haemoglobin concentration, haematocrit, reticulocyte count, ferritin level and erythrocyte deformability were measured on days 5, 14, 28, 42 and 63. Erythrocyte elongation was determined as an indicator of erythrocyte deformability using a shear stress diffractometer (Rheodyn SSD) at shear forces of 0.3 to 60 Pa.

RESULTS

Haemoglobin concentration was significantly higher on days 28 and 42 and reticulocyte percentage on day 28 in the rhEPO group compared to the controls. Serum ferritin was lower in the rhEPO group on day 28. Erythrocyte deformability was significantly increased on days 28 and 42 in the infants receiving rhEPO. We found a strong relationship between erythrocyte elongation and reticulocyte count.

CONCLUSION

RhEPO markedly increases the erythropoiesis in preterm infants in the critical first weeks of life and the anaemia of prematurity is obviously reduced. The erythrocyte deformability improved under rhEPO treatment. Erythrocyte deformability was significantly related to the reticulocyte count indicating that the improvement of erythrocyte deformability was due to the formation of well-deformable young erythrocytes.

Late erythropoietin for preventing red blood cell transfusion in preterm and/or low birth weight infants

BACKGROUND

Hematocrit falls after birth in preterm infants due to physiological factors and blood letting. Low plasma levels of erythropoietin (EPO) in preterm infants provide a rationale for the use of EPO to prevent or treat anemia.

PRIMARY OBJECTIVE

To assess the effectiveness and safety of late initiation of EPO (initiated at 8 days after birth or later) in reducing the use of red blood cell transfusions in preterm and/or low birth weight infants.

SECONDARY OBJECTIVES

Subgroup analyses of low (< 500 IU/kg/week) and high (> 500 IU/kg/week) doses of EPO and within these subgroups analyses of the use of low (< 5 mg/kg/day) and high (> 5 mg/kg/day) doses of supplemental iron, in reducing the use of red blood cell transfusions in these infants.

SEARCH STRATEGY

MEDLINE, EMBASE, CINAHL, abstracts from scientific meetings published in Pediatric Research and reference lists of identified trials and reviews were searched in November 2005/April 2006 and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2006). No language restrictions were applied.

SELECTION CRITERIA

Randomised or quasi-randomized controlled trials of late initiation of EPO treatment (started at eight days of age or later) vs. placebo or no intervention in preterm (< 37 weeks) and/or low birth weight (< 2500 g) neonates. For inclusion the studies needed to provide information on at least one outcome of interest.

DATA COLLECTION AND ANALYSIS

Data were abstracted by the two authors on pre-tested data collection forms. Data were entered by one review author (AO) and checked for accuracy by the other (SA). Data were analysed using RevMan 4.2.8. The statistical methods included relative risk (RR), risk difference (RD), number needed to treat to benefit (NNTB), number needed to treat to harm (NNTH) for dichotomous outcomes and weighted mean difference (WMD) for continuous outcomes reported with their 95% confidence intervals (CI). A fixed effects model was used for meta-analyses. Heterogeneity tests including the I squared (I(2)) statistic were performed to assess the appropriateness of pooling the data.

MAIN RESULTS

Twenty-eight studies enrolling 1302 preterm infants in 21 countries were included. The quality of the trials varied. Most trials were of small sample size. Only one study clearly stated that infants were excluded if they had received red blood cell transfusion prior to study entry (Samanci 1996). A total of 19 studies including 912 infants reported on the primary outcome of "Use of one or more red cell transfusions". The meta-analysis showed a significant effect [typical RR; 0.66 (95% CI; 0.59, 0.74); typical RD -0.21 (95% CI; -0.26, -0.16); typical NNTB of 5 (95% CI 4, 6)]. There was statistically significant heterogeneity [for RR (p < 0.00001), I(2 )= 74.0% and for RD (p = 0.0006), I(2 )=58.9%]. Similar results were obtained in secondary analyses based on different combinations of high/low doses of EPO and iron supplementation. There was a significant reduction in the total volume (ml/kg) of blood transfused per infant (four studies enrolling 177 infants) [typical WMD = -7 ml (95% CI -12, -3)] and in the number of transfusions per infant (nine studies enrolling 567 infants); [typical WMD -0.78 (-0.97, -0.59)]. The effect size was less in a post hoc analyses of high quality studies compared to studies in which the quality was uncertain and in studies that used strict guidelines for red blood cell transfusions vs. studies that did not. There were no significant differences in mortality, retinopathy of prematurity, sepsis, intraventricular haemorrhage, periventricular leukomalacia, necrotizing enterocolitis, bronchopulmonary dysplasia, SIDS, neutropenia, hypertension, or length of hospital stay. Long-term neurodevelopmental outcomes were not reported.

AUTHORS' CONCLUSIONS

Late administration of EPO reduces the use of one or more red blood cell transfusions, the number of red blood cell transfusions per infant and the total volume of red blood cell transfused per infant. The clinical importance of the results for the latter two outcomes is marginal (< 1 transfusion per infant and 7 ml/kg of transfused red blood cells). Any donor exposure is likely not avoided as most studies included infants who had received red cell transfusions prior to trial entry. Late EPO does not significantly reduce or increase any of many important neonatal adverse outcomes including mortality and retinopathy of prematurity. Further research of the use of late EPO treatment to prevent donor exposure is not indicated. Research efforts should focus on limiting donor exposure during the first few days of life in sick neonates, when red blood cell requirements are most likely to be required and cannot be prevented by late EPO treatment.

Postnatal ontogeny of erythropoietin and hematology in free-ranging Steller sea lions (Eumetopias jubatus)

The hormone erythropoietin (EPO) is responsible for the increased production of red blood cells (RBC) in response to tissue hypoxia. While the role of EPO in hematological development has been established in humans and terrestrial mammals, this relationship has never been examined in marine mammals that rely heavily on stored oxygen to maintain aerobic metabolism while diving. Since blood is the major oxygen storage site in marine mammals, it was hypothesized that EPO may have a significant influence on the development of hematology parameters associated with the expansion of blood oxygen stores during development. To explore this hypothesis, serum EPO concentrations were determined by radioimmunoassay in 235 free-ranging Steller sea lions (Eumetopias jubatus), throughout their Alaskan range. Hematocrit (Hct), hemoglobin (Hb), and red blood cell (RBC) counts were also measured, and mean corpuscular hemoglobin content (MCHC), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCV) values determined. Erythropoietin and most hematological parameters varied with age. Hematocrit, Hb, RBC, and MCHC decreased after birth, reached their lowest values at two to three months of age, and then increased to values similar to those of adults by five months of age. Since changes in Hct and Hb account for the majority of the changes in blood oxygen stores and EPO was negatively correlated with both, it appears that EPO may play an important role in blood development of Steller sea lions, similar to previous studies on terrestrial mammals.

Physiology of erythropoietin during mammalian development

Growth is a fundamental process of mammalian development. Several observations regarding regulation of erythropoiesis during growth are not easily explained by the hypoxia-erythropoietin (Epo) concept. This review focuses primarily on this aspect of the physiology of Epo. The question is raised of whether this regulation during growth is based on the hypoxia-Epo mechanism alone, or whether Epo acts in concert with general growth-promoting factors, particularly growth hormone (GH) and the insulin-like growth factors (IGF-I and -II). Supporting the latter hypothesis is the observation that the Epo and GH/IGF systems are activated by hypoxia and share similar receptors and pathways. Recent studies indicate that human fetal and infant growth is stimulated by GH, IGF-I and IGF-II. Epo, GH and IGFs are expressed early in fetal life. Although the rate of erythropoiesis in the fetus is high, serum Epo levels are low. The Epo response to hypoxia in the fetus and neonate is reduced compared with adults. Following delivery the Epo levels vary between species, probably related to the oxygen transport capacity of the hemoglobin (Hb) mass. IGF-I levels are low in the fetus and increase slowly following birth, except in preterm infants in whom the levels decline. In all mammals Hb declines following birth, giving rise to "early anemia". Except in the human, Epo levels increase proportionally with the fall in Hb, but there is a discrepancy between the curves for serum immunoreactive Epo (siEpo) and for erythropoiesis stimulating factors (ESF): the latter include other stimulatory factors in addition to Epo. Hypertransfusion of mice in the period of "early anemia" suppresses siEpo, but not ESF and erythropoiesis, as it does in adult mice. GH and IGF-I have direct effects on erythropoiesis in vitro and act particularly at the later stages of red cell differentiation. IGF-I acts synergistically with Epo, and its effects are most marked when Epo levels are low. Human recombinant (rhu) IGF-I stimulates erythropoiesis in neonatal rats, but not in newborn mice and lambs. In adult mice, in hypophysectomized rats and in mice with end-stage renal failure, however, a stimulatory effect of this growth factor was found on red cell production. RhuGH stimulates erythropoiesis in GH-deficient short children.

CONCLUSION

Fetal and early postnatal erythropoiesis are dependent on factors in addition to Epo. The likely candidates are GH and IGF-I. The in vitro stimulating effects of these factors on erythropoiesis are convincing, but more data are needed on the in vivo effects.

Iron status and the treatment of the anemia of prematurity

Many unanswered issues regarding rhEPO therapy in prematurity remain, including which premature infants best respond to rhEPO, what the long-term effect of decreased erythrocyte transfusions is, how nutritional supplementation optimizes the effect of rhEPO, whether or not rhEpo therapy causes iron deficiency later in life, and whether or not it is safe to supplement with parenteral iron. Further study of rhEPO therapy and iron status in prematurity is necessary.

Neonatal iron nutrition

Preterm infants are prone to iron deficiency. Their total body iron content at birth is low and gets further depleted by clinical practices such as uncompensated phlebotomy losses and exogenous erythropoietin administration during the neonatal period. Early iron deficiency appears to adversely affect cognitive development in human infants. To maintain iron sufficiency and meet the iron demands of catch-up postnatal growth, iron supplementation is prudent in preterm infants. A dose of 2-4 mg/kg/day is recommended for preterm infants who are fed exclusively human milk. A dose of 6 mg/kg/day or more is needed with the use of exogenous erythropoietin or to correct preexisting iron deficiency. However, due to the poor antioxidant capabilities of preterm infants and the potential role of iron in several oxidant-related perinatal disorders, indiscriminate iron supplementation should be avoided.

The role of high-dose oral iron supplementation during erythropoietin therapy for anemia of prematurity

OBJECTIVE

To assess whether a high intake of oral iron would increase the effect of recombinant human erythropoietin (rHuEPO) on hemoglobin synthesis.

METHODS

We studied 30 preterm infants (gestational age 29+/-1.8 weeks, birth weight 1161+/-200 g, at age of 28+/-10 days) who were randomly assigned to receive either 8 mg/kg per day (n=15) or 16 mg/kg per day of oral iron during a course of rHuEPO therapy (900 microg/kg per week) for a duration of 4 weeks. Both groups were comparable in regard to clinical and laboratory data at the time of enrollment.

RESULTS

rHuEPO caused a significant increase in reticulocyte count in the low- and high-dose iron groups, 17.1+/-5.3 to 34.7+/-9.2 and 16.3+/-3.3 to 42.5+/-5.6 (10(9)/l), respectively (p<0.05). However, in both groups, hematocrit values remained stable at the end of the study as compared to baseline (0.35+/-0.03% vs. 0.30+/-0.03%, 0.35+/-0.05% vs. 0.30+/-0.03%, NS) and in both groups there was a comparable and significant decrease in ferritin level (259+/-109 to 101+/-40 and 168+/-54 to 69+/-38 microg/l, respectively; p<0.01). The rates of bloody stools without any evidence of necrotizing enterocolitis were not significantly different between the two treatment groups (1/15 vs. 4/15, NS).

CONCLUSION

We conclude that a higher dose (16 mg/kg per day) of oral iron is not more beneficial when compared to a lower dose (8 mg/kg per day) during rHuEPO therapy for anemia of prematurity. Further studies will define the optimal dosage and route of administration of iron supplementation during rHuEPO therapy.

Meta-analysis of controlled clinical trials studying the efficacy of rHuEPO in reducing blood transfusions in the anemia of prematurity

BACKGROUND

Recombinant human EPO (rHuEPO) has not gained broad acceptance in the treatment of the anemia of prematurity, because its efficacy in diminishing RBC transfusions is questionable. Meta-analysis was used to investigate the extent and reasons for variation in the results of published clinical trials.

STUDY DESIGN AND METHODS

Prospective controlled trials published from 1990 through 1999 were retrieved; 21 met the criteria for meta-analysis. Calculated across these studies were the summary OR of RBC transfusion in treated neonates as compared with controls and the summary mean difference between controls and treated neonates in the volume of RBCs transfused and the number of RBC transfusions per infant. Twelve study descriptors were examined as possible reasons for the variation in results.

RESULTS

Results of 21 eligible studies varied widely (p<0.001 for the Q test statistic), and this variation persisted in most analyses when studies were stratified by individual study descriptors. When the difference in volume of RBCs transfused was the outcome measure, variation was modest across the four studies with highly desired characteristics (i.e., high blindness and design quality scores, "conservative" transfusion criteria, and the majority of neonates weighing <1 kg at birth), and treatment with rHuEPO reduced RBC transfusions by an average of 11.0 mL per kg (p<0.001).

CONCLUSION

Benefit from rHuEPO is detected across high-quality studies using conservative RBC transfusion criteria. However, there is extreme variation overall in the findings of available trials, and-until this variation is accounted for-it is premature to recommend rHuEPO as standard treatment for the anemia of prematurity.

[Recombinant human erythropoietin in premature infants. Evaluation of a one year experience]

Recently, recombinant human erythropoietin (rhEPO) has been claimed to diminish red blood cell transfusions in premature infants. After a year of experience, we investigated whether early rhEPO treatment would reduce the need for transfusion.

PATIENTS AND METHODS

Fifty premature infants of gestational age < or = 32 weeks admitted to our NICU in 1997, received rhEPO 750 UI/kg/week from day 3 to 5 for six weeks. They were compared with 50 untreated controls admitted in 1996.

RESULTS

The treatment and control groups did not differ for gestational age, weight at birth, CRIB score, and blood losses. We were not able to detect any difference in the number of transfused infants, and in the number of transfusions per infant until discharge. However, treated infants received significantly fewer transfusions per infant between day 16 and day 45 (0.42 +/- 0.67 vs. 0.8 +/- 0.99). Infants with a birth weight between 1,000-1,250 g received fewer transfusions in the EPO group.

CONCLUSION

rhEPO treatment can be useful, but in association with other procedures: conservative transfusion criteria, minimization of phlebotomy losses and early iron supplementation.

Comparison of the effects of theophylline and caffeine on serum erythropoietin concentration in premature infants

Theophylline administration has been shown to attenuate erythropoietin (EP) production in adults; the effect of caffeine is not known. Our aim was to determine whether caffeine and theophylline had similar effects on EP production in the premature newborn. If caffeine was found to have a greater effect, this would influence prescribing habits. Fifty preterm infants (mean gestational age 28 weeks) who had clinically significant apnoea were randomized to receive theophylline (4 mg/kg then 2 mg/kg twice daily) or caffeine (10 mg/kg then 2.5 mg/kg once daily). The methylxanthines were continued at least until discharge from the NICU and the dosage altered to keep the levels within the therapeutic range. As an assessment of EP production, serum EP concentrations were measured. Blood for EP, haemoglobin, reticulocyte count, theophylline and caffeine levels was obtained prior to treatment and at least during weeks 3 and 7. There was no significant difference in the mean EP level in the two groups taken prior to treatment at a median age of 2 days of life. There were similar falls in haematocrit and haemoglobin in the two groups during the study period compared to pre-treatment values. At that time, however, the median reticulocyte count was higher in the caffeine compared to the theophylline treated infants (P < 0.05). This was associated with a rise compared to baseline (median 10.0-0.2 mU/ml) in the mean EP levels in the caffeine group and a decrease from a median of 10.1 to 8.3 mU/ml in the theophylline group, but the EP levels in the two groups at week 7 did not differ significantly.

CONCLUSION

These results suggest that caffeine does not have a greater impact than theophylline on EP production.

The role of erythropoietin in the anemia of prematurity

Neonatal erythropoiesis is limited by a relatively inadequate production of erythropoietin. This is likely the result of dependence on the hepatic production of erythropoietin and an incomplete switchover to renal production. The present model of neonatal erythropoiesis suggests that the use of exogenous erythropoietin should correct the early anemia of prematurity that is observed at 6 weeks of age in premature newborns. Randomized, controlled trials of erythropoietin use in very low birthweight infants are reviewed. The data support the conclusion that erythropoietin at doses of > or = 750 u/kg/wk started at less than 7 days of age results in improved reticulocyte counts and hemoglobin levels, but does not reduce the number of infants who will be exposed to blood products. Erythropoietin at doses of > or = 600 u/kg/wk started at an average of 21 days of life improves reticulocyte counts and hemoglobin levels, and reduces the number of infants will will require late transfusion, but does nothing for the bulk of infants who are transfused before that age.