An age dependent response to hydroxyurea in pediatric sickle cell anemia patients with alpha thalassemia trait

Hydroxyurea (HU) is a key drug therapy for individuals with sickle cell anemia (SCA), yet its clinical and hematologic responses can be variable. Various studies have reported the role of α-thalassemia as one of the most prevalent heritable traits that may modify HU response. We provide data from 62 pediatric and adolescent patients with SCA, 26 with co-inherited α-thalassemia trait. Our data suggest that altered hematologic and clinical responses to HU therapy are noted in adolescent SCA individuals with co-inherited α-thalassemia trait. Adolescent patients who co-inherited α-thalassemia trait had a greater reduction in vaso-occlusive episodes compared to those without α-thalassemia, despite a less robust fetal hemoglobin induction as well as a lower maximum HU dose. This clinical improvement was associated with a lower MCH and higher RBC count. Responses to HU in younger SCA children (ages 5-11 years) with co-inherited α-thalassemia trait, compared to those without α-thalassemia trait, did not show any difference in number vaso-occlusive episodes, fetal hemoglobin induction and change in MCH and RBC count.