Changes in the peripheral blood cell count in pediatric patients with Down syndrome

OBJECTIVES: Down syndrome (DS) is associated with multiple complications, including a high risk of leukemia and thyroid dysfunction. This clinical study aimed to examine the complete blood cell count in patients with DS without leukemia or transient abnormal myelopoiesis. We also aimed to evaluate the effect of thyroid dysfunction on hematological anomalies in DS. METHODS: We analyzed the peripheral blood cell count in 23 pediatric patients with DS with and without thyroid dysfunction and in 17 pediatric patients without DS with thyroid dysfunction. RESULTS: Patients with DS showed greater neutrophilia and lymphopenia than did patients with DS and hypothyroidism and patients with hypothyroidism. Surprisingly, patients with DS showed a significant degree of eosinopenia in the peripheral blood. Interestingly, hypothyroidism had an attenuating effect on different lineages in the complete blood count. However, these anomalies were specific for DS. CONCLUSIONS: Our clinical findings support previous data on DS-associated changes in the complete blood count. Our study also shows novel alterations in the complete blood count in leukemia-free patients with DS in association with hypothyroidism. The attenuating effect of thyroid dysfunction on changes in different lineages in the context of DS is novel and deserves further analysis in larger studies.