[Effect of chemoradiotherapy on the pituitary-thyroid system in children with Hodgkin's disease]

The functional status of the thyroid gland was evaluated in 63 children with Hodgkin's disease, aged 4-15 years, before, in the course of and 5 years after chemoradiation therapy. Thyroxin (T4), triiodothyronine (T3) and thyroid-stimulating hormone (TSH) in the blood were assayed. The disease was shown to disrupt the pituitary-thyroid system leading to hypothyroidism development which progressed as the disease advanced. While chemotherapy brought the balance between the peripheral thyroid hormone levels and TSH back to normal, thyroid function decreased again following radiotherapy of the neck. The most pronounced and persistent failure of the pituitary-thyroid system was registered with the total target dose of 30 Gy and higher. Irradiation in a dose of 20 Gy caused less disruption and the function was spontaneously restored within 12 months after the treatment.