Endocrine Abstracts

Introduction

Primary hypothyroidism, which is one of the main endocrine complications of allogenic stem cells transplantation (allo-SCT), has been largely studied in children. Conversely, data on adults are still limited with a reported incidence widely ranging between 9 and 47%. Older age, multiple allo-SCT, chronic Graft vs Host Disease (cGVHD), prolonged immunosuppressive therapy and high-dose total body irradiation (TBI) have been indicated as potential risk factors. The aims of this observational, cross-sectional study were to assess the prevalence of post-allo-SCT hypothyroidism in adult recipients, to analyse its variation over time and to detect predictive factors.

Methods

Among 462 patients who underwent allo-SCT at our hospital between January 2010 and December 2017, 218 where alive and in active follow-up at the time of the study. Of them, 195 (M 107; F 88; median age 53.3 years) were recruited and divided into 3 groups according to time elapsed after allo-SCT (1–3 years: n 78; 3–5 years: n 50; >5 years: n 67). Data on pre-transplant TSH and fT_c levels were available for all patients. After the transplant, TSH, fT4 and anti-thyroperoxidase antibodies (AbTPO) were evaluated.

Results

TSH levels were significantly lower before (median 1.7, IQR 1.2–2.4 µU/ml) than after allo-SCT (median 2.3, IQR 1.5–3.5 µU/ml; P < 0.0001). Forty-six (23.6%) patients developed post-transplant hypothyroidism, with a higher prevalence in females (F 35.2%, M 14.0%; P < 0.001) and at earlier time points (1–3 yrs: 28.2%; 3–5 yrs: 24%; >5 yrs: 17.9%). At the pre-transplant evaluation, patients who developed hypothyroidism showed higher TSH and lower fT₄ levels (TSH median 2.4, IQR 1.7–3.3 µU/ml; fT4 median 10.2, IQR 8.9–11.7 pg/ml) compared to those with preserved thyroid function (TSH median 1.5, IQR 1.1–2.1 µU/ml; fT4 median 11.2, IQR 10.0–12.1 pg/ml; P < 0.0001 and < 0.05, respectively). Patients with post-transplant hypothyroidism had higher prevalence of AbTPO positivity and of acute GvHD (P < 0.05 for both). Multiple regression analysis, corrected for time after allo-SCT, radiotherapy and acute GVHD, identified male gender as a negative predictor of hypothyroidism (OR 0.283, 95%IC 0.121–0.660; P < 0.05) and higher pre-transplant TSH levels as a positive one (OR 1.797, 95%IC 1.275–2.534; P < 0.001).

Conclusions

About one out of four patients developed hypothyroidism after allo-SCT, with a greater risk for females and in the presence of acute GHVD. Pre-transplant TSH levels seem to predict the onset of post-SCT hypothyroidism.