TO THE GENETIC RISK AFTER HIGH-DOSE RADIO IODINE THERAPY WITH REGARD TO THE GONADAL DOSE

Aim: The genetic risk for the offspring of patients treated with high doses of radioiodine was to be assessed with special regard to the gon adal dose caused by diagnostic and therapeutic procedures. Methods: 41 young females (aged between 19 and 39 years) and four young males (ag ed 26 to 36 years) treated with radioiodine because of a thyroid carci noma were interviewed by use of a questionnaire. The course of pregnan cy and birth history could be documented as well as the congenital and developmental conditions of 56 children. Results: The amount of radio activity applied for therapy and whole body scans ranged over 4,144 an d 35,15 GBq I-131; the individual gonadal dose was calculated based on the MIRD model and ranged over 0,2 and 2,2 Sv (0,51 Sv at a mean). Th e period of time between the last radioiodine application and confinem ent was at least 9 months, not exceeding 14 years. As to the course of pregnancy and birth two early abortions, one extrauterine gravidity a cid one premature birth due to an insufficiency of the placenta were s tared. In one case a chromosomal translocation 7/14 occured as a genet ic defect which lead to an interruption. The children's development wa s unconspicuous except of two cases of neurodermatitis as well as mult iple allergies and an early closure of the anterior fontanelle in one child each. Conclusion: Although the genetic risk is supposed to incre ase with the gonadal dose achieved (doubling dose 1 Sv) and the increa sed risk of any congenital anomaly was calculated as about 13% at a me an in our patients, the rate of genetic determined diseases was not el evated (1,8% or 1/57). Thus, no increase of genetic defects or congeni tal malformations was reported in a total of 408 children described in the literature and in our group.