Anemia of prematurity: determinants of the erythropoietin response

Development and validation of a novel risk classification tool for predicting long length of stay in NICU blood transfusion infants

Newborns are as the primary recipients of blood transfusions. There is a possibility of an association between blood transfusion and unfavorable outcomes. Such complications not only imperil the lives of newborns but also cause long hospitalization. Our objective is to explore the predictor variables that may lead to extended hospital stays in neonatal intensive care unit (NICU) patients who have undergone blood transfusions and develop a predictive nomogram. A retrospective review of 539 neonates who underwent blood transfusion was conducted using median and interquartile ranges to describe their length of stay (LOS). Neonates with LOS above the 75th percentile (P75) were categorized as having a long LOS. The Least Absolute Shrinkage and Selection Operator (LASSO) regression method was employed to screen variables and construct a risk model for long LOS. A multiple logistic regression prediction model was then constructed using the selected variables from the LASSO regression model. The significance of the prediction model was evaluated by calculating the area under the ROC curve (AUC) and assessing the confidence interval around the AUC. The calibration curve is used to further validate the model's calibration and predictability. The model's clinical effectiveness was assessed through decision curve analysis. To evaluate the generalizability of the model, fivefold cross-validation was employed. Internal validation of the models was performed using bootstrap validation. Among the 539 infants who received blood transfusions, 398 infants (P75) had a length of stay (LOS) within the normal range of 34 days, according to the interquartile range. However, 141 infants (P75) experienced long LOS beyond the normal range. The predictive model included six variables: gestational age (GA) (< 28 weeks), birth weight (BW) (< 1000 g), type of respiratory support, umbilical venous catheter (UVC), sepsis, and resuscitation frequency. The area under the receiver operating characteristic (ROC) curve (AUC) for the training set was 0.851 (95% CI 0.805-0.891), and for the validation set, it was 0.859 (95% CI 0.789-0.920). Fivefold cross-validation indicates that the model has good generalization ability. The calibration curve demonstrated a strong correlation between the predicted risk and the observed actual risk, indicating good consistency. When the intervention threshold was set at 2%, the decision curve analysis indicated that the model had greater clinical utility. The results of our study have led to the development of a novel nomogram that can assist clinicians in predicting the probability of long hospitalization in blood transfused infants with reasonable accuracy. Our findings indicate that GA (< 28 weeks), BW(< 1000 g), type of respiratory support, UVC, sepsis, and resuscitation frequency are associated with a higher likelihood of extended hospital stays among newborns who have received blood transfusions.

Hematological changes in neonatal mice with phlebotomy-induced anemia

BACKGROUND

Anemia is a nearly universal diagnosis in preterm infants, caused by phlebotomy, and exacerbated by the underlying erythropoietic immaturity. Newborn infants are exposed to the unique stressor of fetal-to-neonatal transition, which requires significant adaptation ex utero. Accordingly, the preterm infant's response to anemia may alter the ability to confront underlying illness. This study utilized our preclinical mouse model of phlebotomy-induced anemia (PIA) to comprehensively investigate associated hematological changes.

METHODS

C57BL/6 mice were subjected to timed phlebotomy between postnatal days 2--10 to induce severe anemia. Complete blood counts were determined by the Sysmex XT-2000iV analyzer.

RESULTS

Anemic pups showed a gradual reduction of RBC and hemoglobin (Hb) and increased reticulocyte (RET) counts and red cell distribution width (RDW), however, with reduced RET-Hb from postnatal day (P) of 4 onwards. Elevated levels of high fluorescent RET and immature reticulocyte fraction (IRF) were noted in anemic mouse pups, but low and medium fluorescent RET were reduced. Also, the reduction of mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) were noted in anemic pups. No changes were seen in lymphocytes, but monocytes and neutrophils were significantly elevated from P4-P6.

CONCLUSIONS

PIA in mouse pups is associated with hematological changes that may be exacerbating factors in neonatal diseases.

IMPACT

Anemia is common and often severe in premature infants. Investigation of hematological parameters in settings of preclinical anemia may be an index of therapeutic strategies. Preclinical model evaluating the effects of neonatal anemia on the remainder of complete blood count. Detailed time kinetic phlebotomy-induced anemic mice enable us to study the impact on developmental delays in erythropoiesis and possible strategic intervention. Hematological effects of severe anemia in mice might provide insight on how best to investigate anemia in preterm infants.

Exposure to high levels of oxygen in neonatal rats induce a decrease in hemoglobin levels

BACKGROUND

Anemia of prematurity is common in extremely preterm neonates, and oxygen exposure may participate to anemia by inhibiting erythropoietin secretion. We aimed to determine whether hyperoxia exerts an independent role in the occurrence of the anemia of prematurity.

METHODS

Sprague-Dawley pups were exposed to 80% oxygen or room air from days 3 to 10 of life. Main outcome was the difference in hemoglobin and circulating erythropoietin levels in animals exposed to hyperoxia at 10 days of life. We performed a complete blood count analysis using fluorescent laser flow cytometry and measured circulating erythropoietin levels using ELISA.

RESULTS

We found lower hemoglobin in the hyperoxia group, compared to the normoxia group, both in males (70 ± 3 versus 78 ± 2 g/l) and in females (71 ± 2 versus 81 ± 3 g/l) at 10 days of life. Reticulocyte count was not increased in the hyperoxia group. Circulating erythropoietin levels were lower at 10 days of life in the animals exposed to hyperoxia, both in males (33 ± 7 versus 73 ± 6 pg/ml) and in females (37 ± 5 versus 66 ± 3 pg/ml), but were similar at 28 days of life.

CONCLUSION

Neonatal exposure to hyperoxia decreases hematopoiesis in rats.

IMPACT

Mechanisms leading to anemia of prematurity are not well known and their study in humans is complicated due to multiple confounders. This study shows for the first time that exposure to high concentrations of oxygen in the neonatal period decreases hematopoiesis in rats, providing insight on the pathophysiological mechanisms of the anemia of prematurity. This research paves the way for future therapeutic developments aiming to reduce the burden of anemia of prematurity and the necessity of red blood cell transfusions in extremely preterm neonates.

Anemia of prematurity: how low is too low?

Anemia of prematurity (AOP) is a common condition with a well-described chronology, nadir hemoglobin levels, and timeline of recovery. However, the underlying pathophysiology and impact of prolonged exposure of the developing infant to low levels of hemoglobin remains unclear. Phlebotomy losses exacerbate the gradual decline of hemoglobin levels which is insidious in presentation, often without any clinical signs. Progressive anemia in preterm infants is associated with poor weight gain, inability to take oral feeds, tachycardia and exacerbation of apneic, and bradycardic events. There remains a lack of consensus on treatment thresholds for RBC transfusion which vary considerably. This review elaborates on the current state of the problem, its implication for the premature infant including association with subphysiologic cerebral tissue oxygenation, necrotizing enterocolitis, and retinopathy of prematurity. It outlines the impact of prophylaxis and treatment of anemia of prematurity and offers suggestions on improving monitoring and management of the condition.

Advances in extracorporeal membrane oxygenator design for artificial placenta technology

Extreme prematurity, defined as a gestational age of fewer than 28 weeks, is a significant health problem worldwide. It carries a high burden of mortality and morbidity, in large part due to the immaturity of the lungs at this stage of development. The standard of care for these patients includes support with mechanical ventilation, which exacerbates lung pathology. Extracorporeal life support (ECLS), also called artificial placenta technology when applied to extremely preterm (EPT) infants, offers an intriguing solution. ECLS involves providing gas exchange via an extracorporeal device, thereby doing the work of the lungs and allowing them to develop without being subjected to injurious mechanical ventilation. While ECLS has been successfully used in respiratory failure in full-term neonates, children, and adults, it has not been applied effectively to the EPT patient population. In this review, we discuss the unique aspects of EPT infants and the challenges of applying ECLS to these patients. In addition, we review recent progress in artificial placenta technology development. We then offer analysis on design considerations for successful engineering of a membrane oxygenator for an artificial placenta circuit. Finally, we examine next-generation oxygenators that might advance the development of artificial placenta devices.

High Prevalence of Iron Deficiency Despite Standardized High-Dose Iron Supplementation During Recombinant Erythropoietin Therapy in Extremely Low Gestational Age Newborns

OBJECTIVE

To assess the effects of protocolized recombinant human erythropoietin (r-HuEPO) therapy and standardized high dose iron supplementation on hematologic and iron status measures in a cohort of extremely low gestational age newborns (ELGANs).

STUDY DESIGN

Charts of extremely low gestational age newborns admitted from 2006 to 2016 and who had received r-HuEPO per neonatal intensive care unit protocol were reviewed. The r-HuEPO was started at a dose of 900 IU/kg per week after 7 days of age and continued until 35 weeks postmenstrual age. Oral iron supplementation at 6-12 mg/kg per day was used to maintain a transferrin saturation of >20% during r-HuEPO treatment. Data on demographic features, hematologic and iron panel indices, red blood cell transfusions, and clinical outcomes were collected. Quartile groups were created based on serum ferritin levels at the conclusion of the r-HuEPO treatment and the quartiles were compared.

RESULTS

The cohort included 116 infants with mean gestational age 25.8 ± 1.5 weeks and birth weight 793 ± 174.1 g. The r-HuEPO promoted erythropoiesis as indicated by increasing hemoglobin, hematocrit, and reticulocyte count. Serum ferritin decreased over time and was ≤75 ng/mL in 60.2% of infants at the conclusion of r-HuEPO therapy; 87% received packed red blood cell transfusions. Transfusion volume, total iron intake, total iron binding capacity, and transferrin concentration differed among infants in the different serum ferritin quartiles (P < .05).

CONCLUSIONS

In extremely low gestational age newborns, r-HuEPO therapy promoted erythropoiesis. Despite a biomarker-based standardized high-dose iron supplementation, the majority of infants had evidence of iron deficiency to a degree that is associated with reduced brain function.

Duration of neonatal oxygen supplementation, erythropoiesis and blood pressure in young adults born preterm

BACKGROUND

Although erythropoiesis is impaired and anaemia frequent in neonates born preterm, haematopoiesis in adults born preterm has not been previously studied.

OBJECTIVE

We, thus, aimed to evaluate haemoglobin and erythropoietin levels in young adults born preterm, to identify neonatal events associated with erythropoiesis in adulthood and to examine the relationships of haemoglobin levels with respiratory function and blood pressure.

METHODS

We assessed a cohort of 101 young adults (ages 18-29) born preterm (≤29 weeks of gestation), in comparison to 105 full-term controls. We measured haemoglobin, erythropoietin levels and blood pressure. We also assessed respiratory function using spirometry.

RESULTS

Compared with controls, tobacco use and sex-adjusted haemoglobin levels were 5.3 (95% CI 2.9 to 7.7) g/L higher in preterm-born individuals, but erythropoietin levels were similar. Duration of oxygen supplementation in the neonatal period was independently associated with higher haemoglobin levels in the preterm group. In young adults born preterm with bronchopulmonary dysplasia, airflow limitation was associated with higher haemoglobin levels. Both systolic (SBP) and diastolic (DBP) blood pressure were increased in individuals born preterm (p=0.042 and p=0.0008, respectively). Higher haemoglobin levels were associated with higher SBP and DBP, independently of term or preterm status. Mediation analysis suggests that haemoglobin increase contributes to 37% and 32% of the effect of preterm birth on SBP and DBP, respectively.

CONCLUSIONS

Haemoglobin levels are higher in young adults born preterm, while erythropoietin levels are similar, especially in case of bronchopulmonary dysplasia and airflow limitation, and haemoglobin increase is associated with elevated blood pressure in this population.

Long-term pediatric hematological morbidity of the early-term newborn

Children born at early term (37 0/7 to 38 6/7 weeks' gestation) are at an increased risk for long-term respiratory, cardiovascular, neurological, and developmental morbidities as compared with children born at full term (39 0/7 to 40 6/7 weeks' gestation). In this population-based cohort analysis, we sought to evaluate the long-term hematological morbidity of early-term born children. The cohort consisted of 223,242 term singleton deliveries. Hospitalizations of the offspring up to 18 years of age involving hematological morbidity were evaluated, including hereditary and acquired anemias, immunodeficiency disorders, coagulation disorders, white blood cell disorders, cytopenias, polycythemia, and myelodysplastic syndrome. Hematological hospitalizations were significantly more common in children delivered at early term as compared with those born at later gestational ages. A Kaplan-Meier survival curve demonstrated a significantly higher cumulative incidence of hematological-related hospitalizations in the early-term born group (logrank p < 0.001). Using a Cox regression model, early-term delivery was found to be an independent risk factor for childhood hematological morbidity with an adjusted hazard ratio of 1.15 (95%CI 1.01-1.30, p=0.027).Conclusion: Early-term delivery appears to be independently associated with pediatric long-term hematological morbidity of the offspring. What is Known? • It has been shown that children born at early term are at increased risk for short-term adverse outcomes including perinatal mortality. • Early-term infants are also at increased risk for long-term morbidity, mainly respiratory. What is New? • Early-term delivery is also independently associated with long-term hematological morbidity of the offspring.

Red Cell Transfusion Practices in Neonatal Intensive Care Unit: An Experience from Tertiary Care Centre

Red cells are the most often transfused blood components during the neonatal period. The aim of the present study was to obtain information regarding the relationship of red cell transfusion with clinical outcomes and to evaluate red cell transfusion practices in neonatal centre of a tertiary care centre. The clinical history, blood component details and laboratory parameters were evaluated with clinical outcomes. The neonates requiring transfusion of red cells were then followed up in the Blood bank for various laboratory parameters. Clinical parameters and clinical outcome were noted from case files. During the study period, 291 neonates were admitted in NICU. 2 neonates were excluded as they were congenitally malformed. Out of 289 admitted neonates, 61 neonates (21.1%) received blood and blood component transfusions. Out of 61 neonates, 20 received red cell transfusions. Mean donor exposure of red cells was 1.2. The mean volume of transfused red cell was 39.6 ml with mean age of red cells was 3.6 days. The mean pre- and post-transfusion Hct was 25.3 and 30.4%, respectively. The most common indication for red cell transfusion was low haemoglobin. There was a significant increase in lactate level and decrease in base excess in transfused neonates. However, no statistically significant correlations were found between transfusions and neonatal weight gain, apnoea, respiratory support and mortality. Transfusion of red cells has significant effect on laboratory parameters as compared to clinical parameters such as weight gain, episodes of apnoea and respiratory support.

Prevention of the anaemia of prematurity

Despite recent advances in neonatal and perinatal medicine, extremely low birth weight infants (ELBW) are at high risk of developing anaemia of prematurity (AOP) requiring packed red blood cell (RBC) transfusions. The benefit of transfusing allogenic RBCs for AOP is a controversial issue, except for disturbances in tissue oxygenation. Although the role of erythropoietin (EPO) in the pathophysiology of AOP is well known, neither early nor late recombinant human EPO therapy alters the number or volume of RBC transfusions. It is also known that one-half of the feto-placental blood volume remains outside the newborn infant's circulation at 30 weeks of gestation if the umbilical cord is clamped immediately. Delayed cord clamping (DCC) and umbilical cord milking (UCM) are the main methods for enhancing placental transfusion. The basic principle of these approaches depends on providing high haemoglobin (Hb) levels to premature infants in the delivery room. The enhancement of placental transfusion clearly results in higher Hb levels at birth, reducing the need for RBC transfusions as well as creating a better haemodynamic status during the initial hours of life. To date, enhancement of placental transfusion in the delivery room by either DCC or UCM seems to be the best preventive measure for AOP. Yet, studies on the associated neurodevelopmental outcomes are insufficient to reach a conclusion. This review summarizes the pathophysiology, treatment and preventative strategies of anaemia of prematurity in light of the current literature.

The effects of umbilical cord milking in extremely preterm infants: a randomized controlled trial

OBJECTIVE

Delayed cord clamping has been shown to decrease the need for transfusion in preterm neonates, but may delay resuscitation. The aim of this study was to determine whether umbilical cord milking compared with immediate cord clamping in extremely preterm deliveries reduces the need for neonatal red blood cell transfusion.

STUDY DESIGN

Women admitted to a tertiary care center and expected to deliver between 24 to 28 completed weeks of gestation were randomized to cord milking before clamping or immediate cord clamping. The primary outcome was the risk of neonatal transfusion, reported as risk ratio (RR) and 95% confidence interval (CI).

RESULT

Of 113 women who were enrolled and randomized, 56 were assigned to cord milking with 36 remaining eligible and completing the study and 57 were assigned to the control group with 39 remaining eligible and completing the study. Albeit not statistically significant, neonates in the cord milking group were less likely to require transfusion compared with those in the control group (RR: 0.86; 95% CI: 0.73 to 1.0). Neonates whose cords were milked had higher hematocrits at birth (P=0.004) and were less likely to develop an intraventricular hemorrhage (P=0.0195).

CONCLUSION

Milking the umbilical cord of a preterm neonate is an easy intervention with the potential to improve perinatal outcomes. Our results suggest that milking of the cord increases the neonate's initial hematocrit and may lessen the need for transfusion in the neonatal period. The observed reduction in the incidence of intraventricular hemorrhage may have important long-term implications that warrant further study.

Risk factors of transfusion in anemia of very low birth weight infants

PURPOSE

Anemia of prematurity is frequent in preterm infants, for which red blood cell (RBC) transfusion remains the treatment of choice. In this study, we attempted to evaluate the characteristics and risk factors of anemia of prematurity, and suggest ways to reduce anemia and the need for multiple transfusions.

MATERIALS AND METHODS

Preterm infants weighing less than 1500 g (May 2008-May 2009) were divided into two groups depending on whether they received RBC transfusions (transfusion group and non transfusion group). Hemoglobin (Hb) concentration, phlebotomy blood loss, and the amount of RBC transfusion were analyzed. Risk factors of anemia and RBC transfusions were analyzed.

RESULTS

Fifty infants that survived were enrolled in the present study: 39 in the transfusion group and 11 in the non transfusion group. Hb concentrations gradually decreased by eight weeks. In the transfusion group, gestational age and birth weight were smaller, bronchopulmonary dysplasia and sepsis were more frequent, full feeding was delayed, parenteral nutrition and days spent in the hospital were prolonged, and phlebotomy blood loss was greater than that in the non transfusion group.

CONCLUSION

Anemia of prematurity was correlated with increased laboratory blood loss, decreased birth weight, prolonged parenteral nutrition, and delayed body weight gain. Accordingly, reducing laboratory phlebotomy loss and parenteral nutrition, as well as improving body weight gain, may be beneficial to infants with anemia of prematurity.

Low versus high haemoglobin concentration threshold for blood transfusion for preventing morbidity and mortality in very low birth weight infants

BACKGROUND

Infants of very low birth weight often receive multiple transfusions of red blood cells, usually in response to predetermined haemoglobin or haematocrit thresholds. In the absence of better indices, haemoglobin levels are imperfect but necessary guides to the need for transfusion. Chronic anaemia in premature infants may, if severe, cause apnoea, poor neurodevelopmental outcomes or poor weight gain.On the other hand, red blood cell transfusion may result in transmission of infections, circulatory or iron overload, or dysfunctional oxygen carriage and delivery.

OBJECTIVES

To determine if erythrocyte transfusion administered to maintain low as compared to high haemoglobin thresholds reduces mortality or morbidity in very low birth weight infants enrolled within three days of birth.

SEARCH METHODS

Two review authors independently searched the Cochrane Central Register of Controlled Trials (The Cochrane Library) , MEDLINE,EMBASE, and conference proceedings through June 2010.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) comparing the effects of early versus late, or restrictive versus liberal erythrocyte transfusion regimes in low birth weight infants applied within three days of birth, with mortality or major morbidity as outcomes.

Anaemia of prematurity: pathophysiology and treatment

Most infants with birth weight <1.0 kg are given multiple red blood cell (RBC) transfusions within the first few weeks of life. The anaemia of prematurity is caused by untimely birth occurring before placental iron transport and fetal erythropoiesis are complete, by phlebotomy blood losses taken for laboratory testing, by low plasma levels of erythropoietin due to both diminished production and accelerated catabolism, by rapid body growth and need for commensurate increase in red cell volume/mass, and by disorders causing RBC losses due to bleeding and/or hemolysis. RBC transfusions are the mainstay of therapy with recombinant human erythropoietin largely unused because it fails to substantially diminish RBC transfusion needs--despite exerting substantial erythropoietic effects on neonatal marrow.

High-dose erythropoietin does not exacerbate retinopathy of prematurity in rats

Preterm infants are at high risk of brain injury, and high-dose recombinant erythropoietin (rEpo) may be therapeutic. However, the effect of rEpo on the development of retinopathy of prematurity (ROP) is unknown. We hypothesized that (1) rEpo would cross the blood-eye barrier and (2) early rEpo would modulate ROP in a rat model. Epo concentrations were measured by ELISA from the plasma and the homogenized eye tissue at timed intervals after rEpo injection. Flat-mounted retinas were prepared from rats given rEpo (0, 5000, or 30,000 U/kg i.p. qid x 3) on postnatal d (P) 1-3 that were raised in room air (RA) or cyclic oxygen exposure (COE) with O2 cycling every 24 h between 50% and 10% for 14 d. Photomicrographs of the fluorescein- or ADPase-stained P20 retinas were examined. rEpo penetrated into the eye in a dose- and time-dependent manner. COE increased retinal vascular pathology and decreased vessel density compared with RA controls. The 30,000 U/kg dose of rEpo increased the ROP clock hour scores, but only in ADPase-stained tissues. In contrast, 5000 U/kg rEpo did not change the incidence or severity of ROP by any measure. High-dose rEpo may protect against preterm brain injury with minimal impact on ROP.

Anemia in the preterm infant: erythropoietin versus erythrocyte transfusion--it's not that simple

Since the late 1980s recombinant human erythropoietin (r-EPO) has been studied as an alternative to packed red blood cell (RBC) transfusion for the treatment of anemia of prematurity in very low birth weight infants. Initial trials and reports focused on r-EPO's ability to prevent or treat anemia of prematurity with the goal of eliminating RBC transfusion but achieved limited success. New concerns about the safety of r-EPO administration have emerged. Past cost-benefit analyses of r-EPO administration versus transfusion for the treatment of anemia of prematurity have been nearly balanced. Autologous transfusion, blood-sparing technologies, changes in RBC transfusion technique and safety, and further elucidation of the risk-benefit ratio of r-EPO therapy may change the cost-benefit analysis.

Anemia in the preterm infant: erythropoietin versus erythrocyte transfusion--it's not that simple

Since the late 1980s recombinant human erythropoietin (r-EPO) has been studied as an alternative to packed red blood cell (RBC) transfusion for the treatment of anemia of prematurity in very low birth weight infants. Initial trials and reports focused on r-EPO's ability to prevent or treat anemia of prematurity with the goal of eliminating RBC transfusion but achieved limited success. New concerns about the safety of r-EPO administration have emerged. Past cost-benefit analyses of r-EPO administration versus transfusion for the treatment of anemia of prematurity have been nearly balanced. Autologous transfusion, blood-sparing technologies, changes in RBC transfusion technique and safety, and further elucidation of the risk-benefit ratio of r-EPO therapy may change the cost-benefit analysis.

Erythropoietin pharmacokinetic/pharmacodynamic analysis suggests higher doses in treating neonatal anemia

BACKGROUND

The establishment of effective treatment of neonatal anemia using recombinant human erythropoietin (r-HuEPO) requires a thorough understanding of the physiology and mechanism of EPO's pharmacologic effect. The purpose of the present preclinical study in sheep was to elucidate the stimulatory effect of EPO on erythroid progenitors and their differentiation into reticulocytes useful in predicting optimal r-HuEPO dosing.

METHODS

Five young adult sheep each underwent two phlebotomies spaced 4-6 weeks apart in which their hemoglobin levels were reduced from 12 g/dL to 3-4 g/dL. Endogenous EPO levels and reticulocyte counts produced in response to anemia were sampled throughout the study and analyzed using a pharmacokinetic/pharmacodynamic (PK/PD) model.

RESULTS

The phlebotomy-induced drop in hemoglobin resulted in a increase in EPO levels, which reached a maximum of 764 +/- 55 mU/mL (mean +/- %CV) in 0.5-2.6 days. The reticulocyte counts increased from baseline values of 76.9 x 10(3) +/- 67/microL to 619 x 10(3) +/- 30/microL in 8 days. The PK/PD analysis indicated an increased maturation time for the reticulocytes (4.88 +/- 35 days) and demonstrated that the E(max) model for EPO's activation of the progenitors did not show significant effect saturation at the endogenous EPO levels reached.

CONCLUSIONS

In extrapolating from the animal pilot experiment, the present study provides a case for the use of higher r-HuEPO doses in human studies to determine if higher doses are more effective in treatment of neonatal anemia to reduce, and in some less severe cases, eliminate, the need for blood transfusions.

Survival and proliferative roles of erythropoietin beyond the erythroid lineage

Since the isolation and purification of erythropoietin (EPO) in 1977, the essential role of EPO for mature red blood cell production has been well established. The cloning of the EPO gene and production of recombinant human EPO led to the widespread use of EPO in treating patients with anaemia. However, the biological activity of EPO is not restricted to regulation of erythropoiesis. EPO receptor (EPOR) expression is also found in endothelial, brain, cardiovascular and other tissues, although at levels considerably lower than that of erythroid progenitor cells. This review discusses the survival and proliferative activity of EPO that extends beyond erythroid progenitor cells. Loss of EpoR expression in mouse models provides evidence for the role of endogenous EPO signalling in nonhaematopoietic tissue during development or for tissue maintenance and/or repair. Determining the extent and distribution of receptor expression provides insights into the potential protective activity of EPO in brain, heart and other nonhaematopoietic tissues.

Neonatal anemia

Neonatal anemia and the need for red blood cell (RBC) transfusions are very common in neonatal intensive care units. Neonatal anemia can be due to blood loss, decreased RBC production, or increased destruction of erythrocytes. Physiologic anemia of the newborn and anemia of prematurity are the two most common causes of anemia in neonates. Phlebotomy losses result in much of the anemia seen in extremely low birthweight infants (ELBW). Accepting a lower threshold level for transfusion in ELBW infants can prevent these infants being exposed to multiple donors.

Is there a role for erythropoietin in neonatal medicine?

Since it was first cloned in 1985, the therapeutic potential of recombinant human erythropoietin in the neonatal hyporegenerative anaemias has been studied-the anaemia of prematurity and haemolytic disease of the newborn. Between 60% and 100% of preterm infants are transfused before three weeks of age, a large proportion receiving more than one transfusion. Blood transfusions are currently also the mainstay of treatment for the hyporegenerative anaemia encountered in neonates with Rhesus disease. Sometimes the situation is complicated by the religious beliefs of the parents. Blood transfusions are associated with numerous risks, from transmission of infection to local injury, and in an effort to minimize these risks Neonatologists have looked to recombinant erythropoietin. Despite an extensive number of studies, there is as yet no clear consensus as to whether the use of recombinant erythropoietin in Neonatal medicine minimizes the need for blood transfusions without risk to the neonate. In this article we review the evidence for and against the use of recombinant erythropoietin in Neonatal medicine.

Executive summary of the workshop on oxygen in neonatal therapies: controversies and opportunities for research

One of the most complex areas in perinatal/neonatal medicine is the use of oxygen in neonatal therapies. To address the knowledge gaps that preclude optimal, evidence-based care in this critical field of perinatal medicine, the National Institute of Child Health and Human Development organized a workshop, Oxygen in Neonatal Therapies: Controversies and Opportunities for Research, in August 2005. The information presented at the workshop included basic and translational oxygen research; a review of completed, ongoing, and planned clinical trials; oxygen administration for neonatal resuscitation; and a review of the collaborative home infant monitoring evaluation study. This article provides a summary of the discussions, focusing on major knowledge gaps, with prioritized suggestions for studies in this area.

Erythropoietin: an update on the therapeutic use in newborn infants and children

Recombinant human erythropoietin (epoetin) has become the most widely used cytokine in the world. Following the success of its use in patients with end-stage renal disease, the usefulness of epoetin in other anaemias was assessed, including paediatric patients, mainly newborns. The treatment or prevention of anaemia of prematurity with epoetin resulted in a significant reduction in the number of transfusions and donor exposure. A clear definition of which premature babies must receive therapy is yet to be established. Other indications in neonatal period include hyporegenerative and haemolytic anaemias. The potential for use of the nonhaematopoietic effects of epoetin in newborn infants is a novel and exciting issue. The role of epoetin as a tissue-protective factor for the CNS and intestinal mucosa is under exhaustive investigation. With the exception of chronic renal failure, in older children the efficacy of epoetin has not been evaluated as in adults. Although an impressive amount of studies were carried out during recent years in adult patients with cancer-related or HIV-infection-related anaemias, thus allowing clear conclusions to be established on its efficacy, only a few trials with a small number of patients have been reported in children. Up-to-date, results in paediatric patients suggest that epoetin therapy is as useful as in adult patients, but prospective, randomised trials including large number of patients are essential to achieve definitive conclusions.

Erythropoiesis in the Rps19 disrupted mouse: Analysis of erythropoietin response and biochemical markers for Diamond-Blackfan anemia

The human ribosomal protein S19 gene (RPS19) is mutated in approximately 20% of patients with Diamond-Blackfan anemia (DBA), a congenital disease with a specific defect in erythropoiesis. The clinical expression of DBA is highly variable, and subclinical phenotypes may be revealed by elevated erythrocyte deaminase (eADA) activity only. In mice, complete loss of Rps19 results in early embryonic lethality whereas Rps19+/- mice are viable and without major abnormalities including the hematopoietic system. We have performed a detailed analysis of the Rps19+/- mice. We estimated the Rps19 levels in hematopoietic tissues and we analyzed erythrocyte deaminase activity and globin isoforms which are used as markers for DBA. The effect of a disrupted Rps19 allele on a different genetic background was investigated as well as the response to erythropoietin (EPO). From our results, we argue that the loss of one Rps19 allele in mice is fully compensated for at the transcriptional level with preservation of erythropoiesis.

Effects of transfusion in anemia of prematurity

The authors aimed to test the hypothesis that blood transfusions depress hematopoiesis in healthy infants with anemia of prematurity (AOP). They also set out to find markers that predict recovery from AOP. Thirty-nine premature babies underwent weekly and post-transfusion measurements of hemoglobin concentrations, reticulocyte counts (RCC), and erythropoietin levels (EPO). RCC and EPO dropped significantly 7 days after a blood transfusion but had normalized after 14 days. Elevated RCC or EPO levels were not predictive of an increase in hemoglobin. Postnatal HbFg/dL was higher in babies who had received transfusions. The authors conclude that blood transfusions depress erythropoiesis in infants with AOP and stimulate HbF synthesis but this effect is not sustained. Reticulocyte counts and erythropoietin levels are unhelpful in predicting recovery from AOP.

Érythropoïétine chez le nouveau-né : efficacité comparée des voies d’administration sous-cutanée et intraveineuse

OBJECTIVE

Our aim was to compare the effectiveness of a one-month treatment with recombinant human erythropoietine (rHuEpo) according to the administration route.

METHODS

Retrospective study based on the data collection from medical files of 64 preterm infant hospitalized in the "institut de puériculture et de périnatalogie" (Paris) between January 13th, 2002 and April 13th, 2002. The first group (N =33) was treated by subcutaneous rHuEpo 750 IU/kg per week, in three injections by week, for one month. The second group (N =15) was treated by continuous infusion of rHuEpo in total parenteral nutrition 1050 IU/kg per week (30% augmentation to compensate the amount absorbed by the filter). The third group (N =16) received 750 IU/kg per week of rHuEpo in three direct intravenous injections. The effectiveness of rHuEpo was evaluated by the absolute reticulocyte count, the level of hemoglobin and the incidence of blood transfusion (multiple logistic analysis of variant and regression).

RESULTS

The absolute reticulocyte count and hemoglobin level were significantly reduced after one month of treatment by continuous infusion of rHuEpo in total parenteral nutrition and direct intravenous injections compared with a one-month treatment by subcutaneous rHuEpo. Hemoglobine level were at 8.8 and 9.6 g/dl vs 10.3 g/dl (P =0.02) and absolute reticulocyte count at 123,000/mm3 and 190,000/mm3 vs 216,000/mm3 (p =0.001). The number of transfused infants was significantly increased with utilization of continuous (40%) and direct intravenous (75%) compared with those treated by subcutaneous route (21.2%) while the ferritin level and phlebotomy losses were not significantly different in the three groups. The number of blood transfusion was significantly linked to phlebotomy losses and administration route of rHuEpo.

CONCLUSION

Our study tends to demonstrate that rHuEpo administered subcutaneously reduces significantly the number of transfusion in contrary to intravenous routes. Waiting for pilot study and new molecules, we recommend subcutaneous administration of rHuEpo to preterm infants 250 IU/kg three times weekly in the treatment of anemia of prematurity.

Effects of vitamin E supplementation during erythropoietin treatment of the anaemia of prematurity

AIMS

To evaluate the effects of vitamin E supplementation on haemoglobin concentration and the requirement for transfusion in premature infants treated with erythropoietin and iron.

METHODS

Randomised, double blind, placebo controlled trial. Thirty infants </=32 weeks gestation and </=1250 g birth weight, who were defined as stable based on minimal requirements for respiratory support and phlebotomy, and absence of major congenital anomalies were enrolled. All were treated with erythropoietin and iron, and were randomised to receive, in addition, either vitamin E 50 IU/day or placebo for eight weeks or until discharge, whichever came first.

RESULTS

Despite higher vitamin E (alpha-tocopherol) levels in the experimental group in weeks 3 (49.0 v 28.1 micro mol/l) and 8 (66.2 v 38.5 micro mol/l), there were no differences in haemoglobin, reticulocyte count, iron concentration, or transfusion requirement.

CONCLUSIONS

Oral vitamin E supplementation at 50 IU/day does not increase the response of preterm infants to erythropoietin and iron. Vitamin E obtained through standard nutrition may have been sufficient or higher doses may be required.

Erythropoietin and hypoxia inducible factor-1 expression in the mid-trimester human fetus

AIM

Infants born prematurely lack a normal response to anemia and fail to increase erythropoietin (Epo) production despite an apparent need for improved tissue oxygenation. This anemia may involve a deficiency in the fetal and premature kidney to produce Epo. To evaluate fetal Epo production, Epo and hypoxia inducible factor-1 (HIF) mRNA expression was measured in the mid-trimester human fetus.

METHODS

Fetal liver and kidney samples were obtained at 11-22 wk of gestation. RNA was isolated and reverse transcribed from snap-frozen specimens. Epo and HIF cDNA concentrations were determined using real-time polymerase chain reaction (PRISM). Epo cDNA concentrations were standardized to HIF concentrations present in each sample.

RESULTS

HIF concentrations remained constant during gestation in kidney and liver samples. Epo cDNA concentrations in kidney did not change from 12 to 22 wk (8.4 +/- 3.4 fg Epo pg(-1) HIF cDNA, 4.8 +/- 1.4, 2.6 +/- 0.4, and 4.2 +/- 1.8 at 11-14, 15-16, 17-19, and 20-22 wk of gestation, respectively), while Epo cDNA concentrations in liver increased with gestation (74.5 +/- 31.9 fg pg(-1) HIF, 23.8 +/- 6.5, 96.4 +/- 19.2 and 276.1 +/- 28.5 at 12-14, 15-16, 17-19 and 20-22 wk of gestation, respectively, p < 0.05, 20-22 wk of gestation liver samples vs all other gestations). Concentrations were 5-20-fold higher in liver than in kidney in each gestational group (p < 0.01, liver vs kidney).

CONCLUSION

HIF concentrations did not change with gestation in liver or kidney. The human fetal kidney produced approximately 5% of the total Epo mRNA measured during the second trimester. It remains to be determined how Epo production by these tissues is affected by premature birth.

Human recombinant erythropoietin in the prevention and treatment of anemia of prematurity

Human recombinant erythropoietin has been studied extensively as treatment for a variety of anemias. Since in vitro studies showed the primary etiology of the anemia of prematurity to be insufficient serum erythropoietin concentrations, clinical trials have evaluated the administration of human recombinant erythropoietin to preterm infants to treat this indication. These studies were followed by pharmacokinetic determinations in animal models and preterm infants, which revealed that preterm infants required greater doses of human recombinant erythropoietin because of a more rapid clearance and greater volume of distribution. Recent studies have focused on the administration of human recombinant erythropoietin in the first weeks of life to alleviate the anemia caused by excessive phlebotomy losses, and to prevent the anemia of prematurity. In addition, human recombinant erythropoietin has been tried clinically in a variety of neonatal populations in an attempt to decrease or eliminate transfusions. Although much information has been accumulated about the clinical use of human recombinant erythropoietin in preterm infants over the last 15 years, many questions remain unanswered. The evolution of clinical practice in the care of extremely low birthweight infants continues to affect the number of transfusions. It is likely that human recombinant erythropoietin administration in combination with instituting rigorous transfusion guidelines and decreasing phlebotomy losses will have the greatest impact in decreasing transfusion requirements in all preterm and term neonates, regardless of the etiology of their anemia.

Thrombopoietin in preterm infants: gestational age-dependent response

PURPOSE

To investigate the factors affecting thrombopoietin (TPO) levels in preterm infants and to determine if TPO levels differ in infants born to mothers with preeclampsia and those infants with culture-proven sepsis.

METHODS

Serial serum samples (N = 95) were obtained from 27 infants less than 33 weeks' gestation. Samples were analyzed for TPO using enzyme-linked immunosorbent assay. All samples had an accompanying complete blood count. Analysis of variance with post hoc analysis by least significant difference test, Mann-Whitney test, or chi2 was used to compare groups, as appropriate. Forward, stepwise linear regression was used to account for potential confounding variables. Data are expressed as mean +/- SD.

RESULTS

TPO levels were not significantly correlated with the absolute platelet counts (R = -0.04, P = 0.69). TPO levels were significantly correlated with gestational age (R= 0.50, P < 0.001) when the platelet count was less than 150,000/mm3. TPO levels were significantly elevated in infants with platelets less than 150,000/mm3 born to mothers with preeclampsia compared with infants with sepsis (1184 +/- 98 vs. 579 +/- 363 pg/mL, P < 0.01). After adjusting for confounding variables using multivariate analysis (model: r2 = 0.43, P < 0.01), gestational age (r2 = 0.26) and preeclampsia (r2 = 0.03) remained significantly associated with TPO levels, whereas sepsis did not contribute to the variability of TPO.

CONCLUSIONS

TPO response of infants with platelets less than 150,000/mm3 is dependent on gestational age. Infants with thrombocytopenia associated with preeclampsia have increased circulating levels of TPO. Infants with thrombocytopenia secondary to sepsis do not show an increase in TPO, but this appears to be an effect of low gestational age.

Effects of early erythropoietin therapy on the transfusion requirements of preterm infants below 1250 grams birth weight: a multicenter, randomized, controlled trial

OBJECTIVES

Infants of </=1250 g birth weight receive multiple erythrocyte transfusions during their hospitalization. We hypothesized that early erythropoietin (Epo) and iron therapy would 1) decrease the number of transfusions received (infants 401-1000 g birth weight; trial 1) and 2) decrease the percentage of infants who received any transfusions (1001-1250 g birth weight; trial 2).

METHODS

A total of 172 infants in trial 1 and 118 infants in trial 2 were randomized to treatment (Epo, 400 U/kg 3 times weekly) or placebo/control. Therapy was initiated by 4 days after birth and continued through the 35th postmenstrual week. All infants received supplemental parenteral and enteral iron. Complete blood and reticulocyte counts were measured weekly, and ferritin concentrations were measured monthly. Transfusions were administered according to protocol. Phlebotomy losses and transfusion data were recorded.

RESULTS

Treated and placebo/control infants in trial 1 received a similar number of transfusions (4.3 +/- 3.6 vs 5.2 +/- 4.2, respectively). A similar percentage of treated and control infants in trial 2 received at least 1 transfusion (37% vs 46%). Reticulocyte counts were higher in treated infants during each week of the study in both trials. Hematocrits were higher among treated infants from week 2 on in both trials. Ferritin concentrations were higher in placebo/controls than in treated infants at weeks 4 and 8 in trial 1 and at week 4 in trial 2. No adverse effects of Epo or supplemental iron occurred.

CONCLUSION

The combination of early Epo and iron as administered in this study stimulated erythropoiesis in infants who were </=1250 g at birth. However, the lack of impact on transfusion requirements fails to support routine use of early Epo.neonate, intravenous iron, donor exposure.

The use of erythropoietin in neonates

Although much information has been accumulated about the clinical use of Epo in preterm infants, many questions remain unanswered. The evolution of clinical practice in the care of extremely ill, preterm infants continues to affect the number of transfusions required during hospitalization. Decreasing phlebotomy losses and instituting standardized transfusion guidelines have both been shown significantly to decrease the transfusion requirements of preterm infants. The administration of Epo likely decreases transfusion need even further; however, the direct impact of each of these actions has not been studied prospectively. It is likely that the combination of instituting rigorous and standardized transfusion guidelines, decreasing phlebotomy losses, and the appropriate use of Epo will have the greatest impact in decreasing transfusion requirements in all preterm and term neonates, regardless of the cause of their anemia.

Effect of early versus late administration of human recombinant erythropoietin on transfusion requirements in premature infants: results of a randomized, placebo-controlled, multicenter trial

OBJECTIVE

The administration of recombinant human erythropoietin (rHuEPO), started after the first 2 weeks of life, reduces the transfusion requirement in premature infants. However, its use throughout the first 2 weeks of life, when anemia results predominantly from phlebotomy losses, remains controversial. We investigated whether early use of rHuEPO would reduce the total transfusion requirement and/or the number of transfusions throughout the first 2 weeks of life.

METHODS

We randomized 114 infants with birth weight (BW) <1250 g to receive rHuEPO (1250 units/kg/week; IV; early group: n = 57) or placebo (late group: n = 57) from day 2 to day 14 of life; subsequently, all the patients received rHuEPO (750 units/kg/week, subcutaneously) for 6 additional weeks. All infants were given oral iron (6 mg/kg/day) and folic acid (2 mg/day).

RESULTS

The early group showed higher hematocrit and reticulocyte counts than the late group in the first 3 weeks of life, but there was no difference in the total number of transfusions (early: 1.8 +/- 2.3 vs late: 1.8 +/- 2.5 transfusion/patient) or the transfusion requirement throughout the first 2 weeks of life (early:.8 +/- 1.1 vs late:.9 +/- 1.3) could be demonstrated. In infants with BW <800 g and total phlebotomy losses >30 mL/kg (n = 29), a lower number of transfusions was received by infants in the early group, compared with late group, from the second week to the end of the treatment (early: 3.4 +/- 1.1 vs late: 5.4 +/- 3.7 transfusion/patient). No clinical adverse effects were observed. Thrombocytosis was detected during the treatment with rHuEPO in 31% of the infants.

CONCLUSIONS

In the whole population, the early administration of rHuEPO induced a rise of reticulocyte counts, but not enough to reduce the transfusion requirement. The most severely ill infants (BW <800 g and phlebotomy losses >30 mL/kg) seemed to benefit from early use of rHuEPO, and this deserves additional study.

Adaptive responses during anemia and its correction in lambs

There is limited information available on which to base decisions regarding red blood cell (RBC) transfusion treatment in anemic newborn infants. Using a conscious newborn lamb model of progressive anemia, we sought to identify accessible metabolic and cardiovascular measures of hypoxia that might provide guidance in the management of anemic infants. We hypothesized that severe phlebotomy-induced isovolemic anemia and its reversal after RBC transfusion result in a defined pattern of adaptive responses. Anemia was produced over 2 days by serial phlebotomy (with plasma replacement) to Hb levels of 30-40 g/l. During the ensuing 2 days, Hb was restored to pretransfusion baseline levels by repeated RBC transfusion. Area-under-the-curve methodology was utilized for defining the Hb level at which individual study variables demonstrated significant change. Significant reciprocal changes (P < 0.05) of equivalent magnitude were observed during the phlebotomy and transfusion phases for cardiac output, plasma erythropoietin (Epo) concentration, oxygen extraction ratio, oxygen delivery, venous oxygen saturation, and blood lactate concentration. No significant change was observed in resting oxygen consumption. Cardiac output and plasma Epo concentration increased at Hb levels <75 g/l, oxygen delivery and oxygen extraction ratio decreased at Hb levels <60 g/l, and venous oxygen saturation decreased and blood lactate concentration increased at Hb levels <55 g/l. We speculate that plasma Epo and blood lactate concentrations may be useful measures of clinically significant anemia in infants and may indicate when an infant might benefit from a RBC transfusion.

Packed red cell volume pattern in Nigerian preterm babies

Weekly packed red cell volume (PCV) was estimated in 57 Nigerian preterm babies whose gestational ages were less than 34 weeks. Babies were excluded if they required exchange blood transfusion or had major congenital malformations. The mean (SD) PCV at birth was 54.6% (8.3). The nadir of the PCV drop was at the 10th-11th week of life. The PCV at the nadir was 29.3% (SD 2.9). The rate of drop in the PCV was most rapid in the 1st 2 weeks (velocity -4.6% per week), but by the 7th week this had decreased to -1.2% per week. The findings indicate a slower rate of postnatal fall in PCV among Nigerian preterms. We recommend that PCV and systemic signs of anaemia be monitored for the 1st 12 weeks of life.

Blood banking issues pertaining to neonatal red blood cell transfusions

Many preterm infants are given multiple red blood cell transfusions during the early weeks of life. Because firm standards for neonatal transfusions do not exist, it is important to consider the pathophysiology of the anemia of prematurity, the goals of transfusion therapy and blood banking practices that best provide safe and effective neonatal transfusions. There is increasing agreement that efforts continue to minimize phlebotomy blood losses, to transfuse per conservative indications and to limit donor exposure by transfusing stored red blood cells from a single unit reserved for an infant--rather than insisting on fresh blood.

[Iron supplementation in preterm infants treated with erythropoietin]

Anemia in premature infants can be prevented by prophylactic treatment with recombinant human erythroprotein (r-huEPO). r-HuEPO as been used for a long time in patients with end-stage renal failure. The main factor which can limit r-HuEPO efficiency is limited iron bioavailability. Adapted iron supplementation is needed when preterm infants receive r-HuEPO in order to avoid the depletion of iron stores. Oral iron supplementation is simple but indigestibility is frequent. Furthermore, the intestinal absorption and utilization of oral iron is limited. Parenteral iron supplementation is possible in infants who are very pre-term as they are parenterally fed during the first weeks of life. There are various preparations of intravenous iron with different physicochemical properties. Toxicity and side-effects of parenteral iron preparations depend on these properties. Two parenteral iron preparations are available in France: iron-saccharate (Venofer) and iron-dextrin (Maltofer). Iron delivery and possible side-effects of these preparations are different and need to be considered before use in preterm infants.

Erythropoietin to prevent and treat the anemia of prematurity

Human recombinant erythropoietin was first cloned in 1985, and is currently available for clinical use for a variety of anemias. Following successful clinical trials using erythropoietin to treat adults with the anemia of end-stage renal disease, the first clinical trial evaluating the use of erythropoietin in preterm infants to treat anemia was published in 1990. Since that initial report, numerous clinical trials have reported various levels of success in the treatment of this anemia. Most recently, erythropoietin has been used in the first weeks of life in an attempt to prevent the anemia of prematurity. This review describes mechanisms of erythropoiesis in the fetus and neonate, and focuses on recent clinical trials evaluating the use of erythropoietin to prevent and treat anemia in preterm infants.

Developmental biology of erythropoiesis

A newborn infant represents the culmination of developmental events from conception through organogenesis. Red cells are critically important for survival and growth of the embryo. During development, erythropoiesis occurs in two distinct forms. The first 'primitive' form consists of nucleated erythroblasts that differentiate within the blood vessels of the extraembryonic yolk sac. The second 'definitive' form consists of anucleate erythrocytes that differentiate within the liver and third trimester bone marrow of the fetus. While adult bone marrow and cord blood now serve as sources of stem cells for the treatment by transplantation of genetic and malignant diseases, the developmental origin of hematopoietic stem cells has not been determined. During the third trimester the fetus grows rapidly and the production of red cells is approximately 3-5 times that of adult steady state levels. Birth brings dramatic changes in oxygenation and erythropoietin production that result in a tenfold drop in red cell production and in a transient 'physiologic' anemia. Other causes of fetal and infant anemias have their origins in development processes. These include globin gene switching in alpha and beta thalassemia, the expression of red cell antigens in alloimmune hemolytic disease, and the poorly understood defects in the regulation of erythropoiesis in Diamond Blackfan anemia. Even in the adult, vestiges of fetal erythropoiesis are evident during transient states of accelerated erythroid expansion. A better understanding of the development of erythropoiesis will bring improvements in the treatment of anemia, not only in the newborn, but also in the fetus and the adult.

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 effect of erythropoietin on the transfusion requirements of preterm infants weighing 750 grams or less: a randomized, double-blind, placebo-controlled study

BACKGROUND

Clinical trials of erythropoietin (EPO) administration to preterm infants have not focused on infants weighing 750 gm or less, the population most likely to receive multiple transfusions because of large phlebotomy losses. It is unknown whether preterm infants weighing 750 gm or less will respond to EPO by accelerating erythropoiesis, or whether EPO administered to this population will decrease blood transfusions.

METHODS

We randomly assigned 28 extremely low birth weight preterm infants (mean +/- SEM: 24.7 +/- 0.3 weeks' gestation, 662 +/- 14 gm birth weight), in the first 72 hours of life, to receive either EPO (200 U/kg/day) or placebo for 14 days and administered transfusions only according to protocol over a 21-day study period. All infants received 1 mg/kg/day iron dextran in their total parenteral nutrition solution during the 14-day treatment period.

RESULTS

During the 21-day study period, a lower number and volume of transfusions were received by the EPO recipients (4.7 +/- 0.7 transfusions per patient and 70 +/- 11 ml/kg per patient) than by the placebo recipients (7.5 +/- 1.1 transfusions per patient and 112 +/- 17 ml/kg per patient; p < 0.05, EPO vs placebo), whereas hematocrits remained similar in the two groups. Reticulocyte counts were similar in both groups on day 1 but were greater in the EPO recipients on day 14 (EPO day 1, 351 +/- 53; EPO day 14, 359 +/- 40 x 10(3)/microl; placebo day 1, 334 +/- 64; placebo day 14, 120 +/- 10 x 10(3)/microl; p < 0.01, EPO vs placebo). Serum ferritin concentrations were similar in both groups at the beginning of the study but were greater in the placebo recipients by day 14 (EPO, 262 +/- 44 microg/L; placebo, 593 +/- 92 microg/L; p < 0.01). No adverse effects of EPO or iron were noted.

CONCLUSION

The combination of EPO and parenteral iron stimulates erythropoiesis in preterm infants weighing 750 gm or less and results in fewer transfusions during their first 3 weeks of life.

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.

Recombinant human erythropoietin: possible role as an antioxidant in premature rabbits

Iron is an important catalyst for free oxygen radicals and lipid peroxidation reactions which may play a role in the pathogenesis of several diseases in premature infants. During the early neonatal period, extracellular iron is available in excessive amounts. We hypothesized that administration of erythropoietin (EPO) mobilizes iron from plasma and inhibits iron-catalyzed reactions. To evaluate this hypothesis, recombinant human EPO (rhEPO) was administered s.c. to premature rabbits delivered at 29-d gestation: one group was kept in room air (RA) and the other in a 100% oxygen environment. Within each group, the animals were randomized to receive placebo or rhEPO at 400 or at 800 U/kg on d 0 and 2 of life. On d 3 or 4, plasma iron and iron saturation of transferrin were assessed. Lipid peroxidation was analyzed in plasma and bronchoalveolar lavage fluid (BAL). Nonsedimentable protein (NSP) and phospholipid content were measured in BAL. Erythropoiesis was evaluated in liver and bone marrow. Treatment with rhEPO decreased plasma iron, decreased iron saturation of transferrin, increased reticulocytes, and increased erythropoiesis in liver and bone marrow in both RA and hyperoxia group. Oxygen exposure increased NSP in BAL and decreased the ability of BAL to inhibit lipid peroxidation as measured by malondialdehyde (MDA) generation compared with RA exposure. In O2-exposed animals, EPO treatment increased the ability of both plasma (EPO 800) and BAL (EPO 400 and 800) to inhibit lipid peroxidation and decreased NSP in BAL (EPO 400). In addition, rhEPO treatment decreased alveolar thickening and proteinaceous exudate in the hyperoxia group. We propose that by stimulating erythropoiesis, rhEPO mobilizes non-heme iron and decreases oxidant injury that depends on the availability of transient metal.

Interpretation of the complete blood count

The authors' impression is that the CBC provides much more information than is routinely used. When anemia is present, the CBC contains considerable information regarding its cause, which can assist in formulating a differential diagnosis and directing further evaluation. White blood cell and platelet count levels may similarly direct practitioners to consider or dismiss underlying conditions. This article assists the pediatrician in optimizing use of this familiar diagnostic tool.