Impact of allogeneic stem cell transplantation on thyroid function

Purpose Primary hypothyroidism is a main endocrine complication after allogeneic stem cells transplantation (allo-SCT) in children, but in adults data on post-SCT hypothyroidism are limited. The aims of this observational, cross-sectional study were to assess the prevalence of hypothyroidism in adult allo-SCT recipients according to time from transplantation, and to identify risk factors. Methods One hundred and eighty-six patients (M 104; F 82; median age 53.4 years) who underwent allo-SCT between January 2010 and December 2017 were enrolled and divided into three groups, according to time from allo-SCT (1–3 years; 3–5 years; > 5 years). Pre-transplant TSH and fT4 levels were available for all patients. After transplantation, TSH, fT4 and anti-thyroperoxidase antibodies (TPO-Ab) were evaluated. Results After a follow-up of 3.7 years, 34 (18.3%) patients developed hypothyroidism, with higher prevalence in females ( p < 0.001) and in patients who received matched unrelated donor grafts ( p < 0.05). No difference in prevalence was found at different time points. Patients who developed hypothyroidism showed higher rate of TPO-Ab positivity ( p < 0.05) and higher pre-transplant TSH levels (median 2.34 µU/ml) compared to those with preserved thyroid function (median 1.53 µU/ml; p < 0.001). Multivariable analysis identified higher pre-transplant TSH levels as a positive predictor of hypothyroidism ( p < 0.005). The ROC curve analysis identified a pre-SCT TSH cutoff of 1.84 µU/ml, which can predict hypothyroidism with sensitivity 74.1% and specificity 67.2%. Conclusions About one out of four patients developed hypothyroidism after allo-SCT, with a greater incidence in females. Pre-transplant TSH levels seem to predict the onset of post-SCT hypothyroidism.