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The reactivation of fetal hemoglobin synthesis during anemia of prematurity
H Bard1, C Lachance, J A Widness
1Department of Pediatrics, Hôpital Sainte-Justine, University of Montreal, Quebec, Canada.
Insights
Severe anemia in premature infants can reactivate fetal hemoglobin (HbF) synthesis. This study found a significant inverse correlation between hemoglobin levels and HbF production, independent of erythropoietin. Transfusions may impact these findings.
Area of Science:
- Neonatal Medicine
- Hematology
- Pediatric Research
Background:
- Increased fetal hemoglobin (HbF) synthesis is observed in conditions like fetal hypoxemia and severe anemia.
- The role of HbF synthesis in anemia of prematurity requires further investigation.
Purpose of the Study:
- To determine if increased HbF synthesis occurs in premature infants experiencing anemia.
- To correlate HbF synthesis levels with the degree of anemia and plasma erythropoietin levels in preterm neonates.
Main Methods:
- Studied thirteen newborn infants (gestational age 29.2 +/- 1.7 wk) at postconceptional age 36.0 +/- 1.1 wk.
- Measured hemoglobin (Hb) levels, HbF synthesis using [3H]leucine incorporation, and plasma erythropoietin via radioimmunoassay (RIA).
- Analyzed alpha, beta, and gamma globin chain synthesis.
Main Results:
- Mean HbF synthesis was 77.9 +/- 8.9% of total Hb synthesis, with Hb levels ranging from 65 to 78 g/L.
- No correlation was found between HbF synthesis and erythropoietin levels.
- A significant inverse correlation (p < 0.01) was observed between Hb level and HbF synthesis.
Conclusions:
- Reactivation of HbF synthesis can occur during severe anemia of prematurity.
- HbF synthesis is inversely related to Hb levels in preterm infants, suggesting a compensatory mechanism.
- Transfusion history may influence observed HbF levels and synthesis rates.
Abstract:
Increased fetal Hb (HbF) synthesis has been shown to occur during fetal hypoxemia and severe anemia. To determine whether increased HbF synthesis occurs during anemia of prematurity, the levels of HbF synthesis were correlated with the degree of anemia and plasma erythropoietin levels. Thirteen newborn infants born at 29.2 +/- 1.7 wk of gestation were studied at a postconceptional age 36.0 +/- 1.1 wk. Hb levels ranged from 65 to 78 g/L. Blood samples were incubated in an amino acid mixture containing [3H]leucine and chromatographed allowing the separation and quantitation of the alpha, beta, and gamma (A gamma T, G gamma, and A gamma I) chains. Erythropoietin was determined by RIA. The mean HbF synthesis was 77.9 +/- 8.9% of total Hb synthesis (range: 61 to 91%). Plasma erythropoietin concentrations were 21.4 +/- 6.4 mU/mL. There was no correlation between the total Hb or HbF synthesis and the level of erythropoietin. There was, however, a significant inverse correlation between the Hb level and HbF synthesis (p < 0.01). Nine infants who had received transfusions during the first few days of life had a mean HbF that was 53.5 +/- 15.2% of total Hb, whereas their HbF synthesis was 78.4 +/- 7.6%. Four of the infants never received transfusions; the total circulating HbF and HbF synthesis in these infants were 87.7 +/- 7.7% and 76.8 +/- 12.7%, respectively. This study shows that there can be a reactivation of HbF synthesis during severe anemia of prematurity.