ESPE Abstracts

Objective: To report the incidence of thyroid dysfunction of patients who underwent allogenic BMT during childhood.

Patients and Methods: Eighty-two patients (56 boys) who were transplanted from an HLA matched donor at a mean age of 7.5±4.8 years (range 0.18–17.5 years) were followed prospectively having measurements of fT4, TSH twice yearly, using chemiluminescence. Patients with elevated TSH higher than 8 μIU/ml had a repeat evaluation in a month time. Thyroid sonogram was performed yearly in patients who have received radiation therapy (RT) and at least once in patients with no history of RT. The initial diagnosis included acute lymphocytic leukemia (ALL), acute myelocytic leukemia, thalassemia, Fanconi anemia, aplastic anemia. The conditioning regimen consisted of Busulfan (16 mg/Kg) + Cyclophosphamide (200 mg/Kg) +/−Fludarabine (100 mg/m²) and antithymocyte globulin. Four patients received total body irradiation (TBI). Seven patients received CNS prophylaxis with 12 Gys for ALL.

Results: The age of the last evaluation was 11.97±5.17 years and the years post BMT were 4.47±3.24. Fifty patients (60.9%) patients had normal thyroid function. Twenty five patients (30.4%) had primary hypothyroidism as evidenced by TSH levels higher than 8 μIU/ml and low or low normal fT4 levels verified with a second measurement and they were started on replacement therapy with L-thyroxine. One patient had TSH higher than 10 μIU/ml which returned to normal and she has normal thyroid function up since. Among the patients with hypothyroidism 2 had received TBI and 3 had received 12Gys prophylaxis RT. Four patients (4.8%) had compensated hypothyroidism as evidenced by TSH level range greater than 5 and less than 8 μIU/ml. None of them had progressed so far to overt hypothyroidism. One patient with a history of TBI, borderline elevation of TSH and low fT4 was considered to have central hypothyroidism and he was started on replacement therapy. One of the hypothyroid patients who had received TBI had a thyroid nodule for which he had an FNA consistent with a dysplastic nodule BETHESDA 1. One of the normothyroid patients who had also received TBI had papillary Ca and underwent thyroidectomy.

Conclusions: Thyroid dysfunction is quite common complication of BMT in this pediatric population. The exact mechanism is not clear. Patients who have received radiation prior to BMT are at increased risk. Patients who underwent BMT should have evaluation of thyroid function routinely in order to prevent overt hypothyroidism.