The Effects of Conditioning Regimen on Thyroid Function After Hematopoietic Stem Cell Transplantation in Children: 2-Year Short Term Follow Up

Background: Long term effect of conditioning regimen such as Total body irradiation (TBI) and chemotherapy has been studied. However short term effect of conditioning regimen on endocrinologic system was not well known. Purpose. Our study aimed to evaluate the effect of conditioning regimen on thyroid function in children who had HSCT after 2 years. Methods:. Date was obtained from retrospective review of medical records who treated malignant hematologic disease and transplanted hematopoietic stem cell in Seoul St. Mary’s hospital from January 1, 2010 to August 31, 2018. Among 563 patients who underwent HSCT for about 9 years, we studied 150 patients who conforming to inclusion criteria of this study. Thyroid function was tested before HSCT and follow 12 and 24 months. Anthropometric date, duration of chemotherapy, history of relapse, graft versus host disease (GVHD) were also analyzed. Results: In patient’s characteristics, median age at HSCT was 10.49 (0.89 - 19.29) years. Out of 150 patients, male was 92 and female was 58. Acute lymphoid leukemia (ALL) was 74, acute myeloid leukemia (AML) was 76. Among them, busulfan based conditioning was done in 53 patients, TBI based conditioning regimen used in 72 and 25 patients had done TBI with busulfan based conditioning regimen. Fifteen patients (12.5%) had thyroid dysfunction after 2 years of HSCT (4 euthyroid sick syndrome, 11 subclinical hypothyroidism and 1 high T4 syndrome). Incidence of thyroid dysfunction by conditioning regimen was different at 2 years after HSCT, higher in TBI with busulfan based group (p = 0.033). In univariate regression analysis, using conditioning regimen, by TBI with busulfan was risk factor of thyroid dysfunction at 2 years after HSCT. Conclusions: TBI with busulfan based group showed higher incidence of thyroid dysfunction and conditioning regimen was risk factor of thyroid dysfunction at 2 years after HSCT.