ESPE Abstracts

Background: Haemopoietic stem cell transplantation (HSCT) has become the treatment of choice for many inherited and acquired pediatric disorders. Cure is not without consequences, and HSCT survivors are at risk of early mortality and developing endocrine complications. Thyroid is highly susceptible to damage from the conditioning therapy for HSCT. The aim of this study is to evaluate the percentage and risk factors of thyroid dysfunction and risk factors of it in allografted children in a single center.

Patients and Methods: This is an observational, retrospective, monocentric cohort study. We included 194 patients (58.6% boys) who survived at least one year after allogenic bone marrow transplantation (BMT) between January 1, 1995, and December 31, 2020. Selected conditioning regimens depended upon diagnosis and protocols active at the time of transplantation. Some patients received irradiation, either CNS prophylaxis, or total body irradiation (TBI). For each patient, thyroid function was evaluated by thyroid-stimulating hormone (TSH), free thyroxine (fT4) and thyroid autoantibodies tests. Furthermore, we analyzed all ultrasound assessments performed during follow-up. Descriptive statistics were performed. Univariate and multivariate logistic models were used to examine the association of the above-mentioned factors with hypothyroidism. Class separation capacity was tested by AUROC (Area Under the Receiver Operating Characteristics).

Results: The mean age at diagnosis was 7.51 years ±0.46 while the mean age at BMT was 7.58 ±0.36. The median follow up was 4.83 years (Interquartile Range : 6.8). We report 33 cases of hypothyroidism (17,7%) for the whole group of patients, 4 after TBI. Factors associated with the onset of thyroid dysfunction were male sex [OR: 3.394, 95% CI(1.328-8.677)], the initial diagnosis of malignancy [OR: 3.450, 95% CI (1.647-7.225)], irradiation therapy [OR: 6.824, 95% CI (3.193-14.584)] and the years after HSCT [OR: 1.147, 95% CI (1.046-1.258)] in the univariate models. Male sex, [OR: 3.005, 95% CI (1.145-7.890)], irradiation, [OR: 2.876, 95% CI (1.120-7.386)], and years after HSCT [OR: 1.148,95% CI (1.042-1.266)], remained also significant in the multivariate model that presents a good class separation capacity [AUC=72%, 95% CI(61.4%-82.4%)]. 17 patients presented with ultrasound anomalies during follow-up. We found 2 cases of secondary thyroid cancer, both among children who had TBI.

Conclusion: Thyroid disorders are common after allogenic bone marrow transplantation in children. Patients who were treated for malignancy and those who have received radiotherapy are at higher risk. A careful follow-up is recommended, in order to detect, prevent, and treat thyroid dysfunction before overt symptoms occur.