Thyroid Disorders Following Hematopoietic Stem Cell Transplantation in Childhood: Impact of Conditioning Regimen on Thyroid Dysfunction, Volume Changes, and Occurrence of Nodules

•Busulfan and total body irradiation (TBI) transplantation conditioning are associated with superimposable occurrence of hypothyroidism.•TBI exposes patients to a higher incidence of benign and malignant nodules.•Busulfan-based regimens are the most thyrotoxic among chemotherapy-only conditioning regimens.•The 5-year cumulative incidence of hypothyroidism is lower with treosulfan-containing regimens than with busulfan-containing regimens.•A reduction in thyroid volume occurs after TBI but not after chemotherapy-based regimens.