Thrombopoietin Level Is Increased in the Serum of Asphyxiated Neonates: A Prospective Controlled Study

Abstract

Thrombopoietin (TPO) is a growth factor that controls platelet production. Despite the known association of chronic hypoxia and acute asphyxia with hematologic changes, TPO had not been studied in neonatal asphyxia. To assess TPO concentrations in the serum of asphyxiated and nonasphyxiated neonates, and examine any correlation with the severity of asphyxia. This prospective study was carried out on 32 asphyxiated neonates and 30 control subjects admitted at Cairo University Medical Center. Asphyxia was defined if two of the following were found: (1) Apgar score </=3 at 1 minute or </=6 at 5 minutes, (2) umbilical cord arterial pH </=7.2 combined with base deficit >/=-10 and (3) clinical evidence of perinatal asphyxia. Encephalopathy was classified clinically according to Sarnat's stages during the first day of life. Platelet count and TPO level (pg/ml) were measured at 1st, 3rd and 7th day of life. : TPO measured on the first day of life did not differ between cases and controls (900.2+/-526.4 vs 726.6+/-441.9 pg/ml, p=0.2). It increased on the 3rd day of life and was significantly higher in asphyxiated infants compared to controls (1291.4+/-627.9 vs 885.5+/-400.3 pg/ml, respectively; p=0.004). This difference remained significant in a logistic regression model controlling for birth weight, sex and mode of delivery (regression coefficient=476.9+/-146.8; p=0.002). In asphyxiated infants (n=32), encephalopathy was classified as mild (n=17), moderate (n=10) and severe (n=5). TPO correlated with the degree of clinical severity on the 7th day of life (r=0.59, p=0.003). TPO did not differ between survivors (n=24) and nonsurvivors (n=8) within the asphyxia group (1197.1+/-596.8 vs 1613.1+/-605.9 pg/ml; p=0.09). Platelet counts correlated negatively with TPO measured on day 1 (r=-0.415; p=0.02), day 3 (r=-0.64; p=0.001) and day 7 (r=-0.562; p=0.007). TPO increased and correlated with severity of asphyxia at 3 and 7 days of life. It correlated negatively with the platelet count at all times.