Reticulated platelet percentages in term and preterm neonates.
OBJECTIVE
The authors aimed to determine whether their reticulated platelet percentage (RP%) analysis technique was suitable for use in term and preterm neonates and to characterize RP% values among nonthrombocytopenic neonates.


METHODS
The authors modified a whole blood method that uses dual-color CD41 staining for platelet gating and thiazole orange for RNA content, combined with RNase treatment of half the sample to subtract non-RNA fluorescence. The RP% was measured in samples from 10 healthy adults and then a longitudinal study was performed in 15 nonthrombocytopenic preterm neonates on days of life 0 to 1, 2 to 5, 6 to 10, and then weekly until day 28. The authors also performed a cross-sectional study of RP% in 22 nonthrombocytopenic neonates of different gestational age (GA) and postconceptional age (PCA).


RESULTS
Overall, neonates had a higher RP% (2.7 +/- 1.6%) than adults (1.1 +/- 0.5%; P < 0.01). In preterm neonates, an increase in the RP% occurred between days 0 and 1 (3.3 +/- 1.3%) and days 2 and 5 (5.1 +/- 1.8%; P = 0.003). By days 6 to 10, the RP% decreased to 3.2 +/- 1.1% and remained unchanged throughout the rest of the study period. In neonates less than 7 days old, an inverse relationship was observed between RP% and GA (n = 20, r = -0.70; P = 0.0005). A correlation between RP% and PCA was not seen in neonates 7 days of age or older.


CONCLUSIONS
This method for determining RP% is suitable for use in term and preterm neonates. In preterm infants, the RP% significantly increases over the first 2 to 5 days of life and then decreases to a stable level over the first 28 days. RP% is generally higher in neonates than in adults. Among preterm infants in the first week of life, the RP% is inversely related to GA.
Saxonhouse
Matthew A
MA
Division of Neonatology, Department of Pediatrics, University of Florida College of Medicine, P.O. Box 100296, Gainesville, FL 32610-0296, USA. Saxonma@peds.ufl.edu
Sola
Martha C
MC
Pastos
Karen M
KM
Ignatz
Mark E
ME
Hutson
Alan D
AD
Christensen
Robert D
RD
Rimsza
Lisa M
LM
D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases; D007234:Infant, Premature; D008137:Longitudinal Studies; D008297:Male; D017701:Reticulocyte Count; D013921:Thrombocytopenia / Q000097:blood*; D034061:Thrombopoiesis / Q000502:physiology