Abstract
Gonadal function was assessed in 28 children (12 male) treated with fractionated TBI (1200-1440 cGy) after conditioning cytotoxic chemotherapy (cyclophosphamide [n=26] or melphalan [n = 2]). All had received prolonged cytotoxic chemotherapy before TBI. 3 boys had received direct testicular irradiation (600-1000 cGy). Gonadal function was assessed by measurement of basal sex steroids levels and the gonadotrophin response to GnRH. Leydig cell function was assessed by the testosterone (T) response to an intramuscular injection of HCG (1000 units). All 5 girls who were pubertal at the time of TBI developed ovarian failure (↑ gonadotrophins, ↓ oestradiol, exaggerated gonadotrophin responses to GnRH), The older prepubertal girls had ↑ basal gonadotrophins +/- exaggerated gonadotrophin responses to GnRH. All other prepubertal girls had normal prepubertal gonadotrophin levels. Unlike children who have received large radiation doses to the thorax, breast agenesis was not seen after induction of puberty with exogenous oestrogen. All boys were prepubertal at the time of TBI and five pubertal at assessment. Only one boy (prepuhertal) had a normal T response to HCG. All 3 boys who had had direct testicular irradiation had abnormal T responses to HCG and elevated gonadotrophins. All other prepubertal boys had normal basal and stimulated gonadotrophin levels, but suboptimal T response to HCG. All pubertal boys at assessment had elevated gonadotrophins and suboptimal T response to HCG. Both boys in late puberty however had normal hasal T levels. Testicular volumes were inappropriately small for pubertal stage. In conclusion the incidence of gonadal dysfunction is high after fractionated TBI. Ovarian failure is very common in the girls and severe damage to the germinal epithelium in boys is universal. Leydig cell damage is almost universal but the extent is often subtle. An HCG test can he helpful in determining the need for androgen replacement therapy which is difficult to predict.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
El-Abiary, W., Ogilvy-Stuart, A., Clark, D. et al. GONADALFUNCTION AFTER FRACTIONATED TOTAL BODY IRRADIATION (TBI). Pediatr Res 33 (Suppl 5), S16 (1993). https://doi.org/10.1203/00006450-199305001-00077
Issue Date:
DOI: https://doi.org/10.1203/00006450-199305001-00077