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Cord blood red cell osmotic fragility: a comparison between preterm and full-term newborn infants
Maria L G Bautista1, Waseem Altaf, Ritu Lall
1Division of Neonatal/Perinatal Medicine, Schneider Children's Hospital at North Shore, North Shore-Long Island Jewish Health System, 300 Community Drive, Manhasset, NY 11030, USA.
Insights
Premature infant cord blood red cells show altered osmotic fragility compared to full-term infants and adults. These cells exhibit increased resistance to hemolysis but contain a more susceptible subpopulation.
Area of Science:
- Neonatal Hematology
- Red Blood Cell Physiology
Background:
- Osmotic fragility of red blood cells (erythrocytes) is a key indicator of membrane integrity.
- Factors like cell shape, deformability, and surface area-to-volume ratio influence erythrocyte lysis.
- Potential differences in cord blood erythrocyte osmotic fragility between preterm and full-term infants remain underexplored.
Purpose of the Study:
- To investigate whether cord blood erythrocyte osmotic fragility differs between premature and full-term newborn infants.
- To compare osmotic fragility in preterm infants, full-term infants, and adults using two distinct assay techniques.
Main Methods:
- Collected cord blood samples from preterm singletons (N=11), preterm multiple births (N=10), full-term infants (N=24), and adult controls (N=22).
- Utilized an osmotic fragility test to determine NaCl concentrations for 20%, 50%, and 80% hemolysis via logistic curves.
- Employed a glycerol lysis test to measure the time required for 50% erythrocyte lysis.
Main Results:
- Erythrocytes from premature infants born via multiple births demonstrated greater hemolysis resistance than those from full-term infants or adults.
- Premature infants exhibited larger differences in NaCl concentration for 80% versus 20% hemolysis, indicating altered fragility.
- Both preterm and full-term infants possessed an erythrocyte subpopulation with delayed lysis time compared to adults.
- A significant correlation (r=-0.603, P<0.0001) was observed between the two osmotic fragility tests.
Conclusions:
- Erythrocytes from premature infants are, on average, less osmotically fragile than those from healthy full-term infants.
- Despite average resistance, premature infant erythrocytes contain a subpopulation that is more susceptible to hemolysis.
- Findings highlight distinct erythrocyte membrane properties in preterm neonates compared to full-term infants and adults.
Background:
The osmotic fragility of red blood cells reflects their membrane ability to maintain structural integrity. The osmolality at which the cells lyse is related to their shape, deformability, surface area/volume ratio and intrinsic membrane properties. In cord blood, there may be differences between premature and term infants, and be influenced by maternal medication and other factors. There have been no definitive findings on possible differences between preterm and full-term infant osmotic fragility.
Aims:
To determine if cord blood erythrocyte osmotic fragility differs between premature and full-term newborn infants, using two parallel techniques.
Patients And Methods:
Cord blood samples were obtained from preterm singletons (N=11), preterm multiple births (N=10), full-term infants (N=24), as well as adults (N=22), for comparison. An osmotic fragility test was used to determine the NaCl concentration at which 20%, 50% and 80% of hemolysis occurred using individual logistic curves. A glycerol lysis test determined the time needed to lyse 50% of red blood cells.
Results:
Cord blood red cells of multiple birth premature infants were more hemolysis-resistant than erythrocytes from full-term infants or adults. Another index of osmotic fragility, the difference in NaCl concentration for 80% and 20% red cell hemolysis showed that premature infants had greater differences than full-term infants or adults. Glycerol lysis time revealed that both preterm and full-term infants had an erythrocyte subpopulation that took longer than adult blood to attain 50% hemolysis. Correlation between both tests was very significant (r=-0.603, P<0.0001, N=67).
Conclusions:
This study shows that erythrocytes of premature infants, although, in average, less osmotically fragile than those of healthy full-term infants, contain a more hemolysis-susceptible cell subpopulation.