Short- and long-term follow-up of thyroid dysfunction after allogeneic bone marrow transplantation without the use of preparative total body irradiation.

We studied the incidence and potential prognostic value of thyroid abnormalities after allogeneic bone marrow transplantation (BMT) without total body irradiation (TBI) conditioning. 77 consecutive patients who received a chemotherapy-alone-based conditioning regimen pretransplant were included. Free serum thyroxine (FT4), free serum triiodothyronine (FT3) and serum thyrotropin (TSH) levels were assayed before and 3 and 14 months after BMT. Patients were classified in three categories: normal thyroid profile if FT3 and FT4 were within the normal range and TSH was normal or low, peripheral thyroid insufficiency (PTI) if TSH was >4 mIU/l, or an 'euthyroid sick syndrome' (ETS) if FT3 and/or FT4 were low and TSH was normal or low. The incidence of thyroid dysfunction at 3 months was 57%, and 29% at 14 months. This was mostly due to the occurrence of ETS which was more frequent at 3 months (48%, 29/61) than at 14 months (19%, 9/48). Furthermore, at 3 months, survival was significantly lower in the ETS group (34.5%) than in the euthyroid group (96.2%), or in the PTI group (83.3%) (P < 0.0001). PTI was observed even in the absence of TBI in 11 patients (14%) and was equally distributed at 3 months (n = 6) and 14 months (n = 5). In conclusion, thyroid dysfunction is not a rare complication even without pretransplant TBI conditioning regimen. Hypothyroidism prevalence was 10%, and ETS, which was more frequently observed, displayed a dismal predictive value at 3 months.