Endocrine Abstracts

Introduction: One of the major causes of deaths in pediatric patients is malignancy. Radiotherapy, which is one of the protocols used in their treatment, may have some disadvantages such as impairing thyroid function. Considering these facts, we decided to determine the incidence of post radiotherapy hypothyroidism in pediatric patients with malignancy.

Methods: In a cross-sectional study 180 patients ranging in age from 1 to 20 years old who survived from malignancy were selected. The study was performed in Sayyed-Alshohada hospital (affiliated to Isfahan University of Medical Sciences, Iran) from 1993 Sep. till 1998 Sep.Baseline data such as age, sex, dose and location of radiation, number of radiotherapy fraction and type of malignancy were derived from medical records. Subjects were evaluated for thyroid function in1999.

Results: The overall incidence of hypothyroidism was 13.3%(12.2% primary hypothyroidism and 1.1% secondary hypothyroidism). There was no statistical difference between euthyroid and hypothyroid patients from aspect of age, sex and dose of radiation (P>0.05). The mean (SD) fractionation number among euthyroid and hypothyroid patients were 22.03 plus/minus12.42 and 23.12 plus/minus 7.12 times, respectively (P>0.05). About 45.8% of hypothyroid patients had received cervical radiation. The observed difference between this group and the other patients was significant (P<0.0001).

Conclusions: Hypothyroidism may be developed after radiotherapy, but none of the factors such as sex, age, dose and fractionation of radiation are important. The area exposed to radiation is important to development of hypothyroidism. We suggest that thyroid function assessment should be performed before and after radiation with certain interval to early detection and treatment of hypothyroidism.