Radioiodine-induced kidney damage and protective effect of amifostine: An experimental study.

BACKGROUND: Ablative radioiodine-131 ((131)I) therapy is used in the standart treatment procedure of thyroid carcinoma and procedures using (131)I represent the majority of Nuclear Medicine therapeutic procedures. The principal route of (131)I excretion after the administration of (131)I is the urine. Amifostine is an organic thiophosphate ester prodrug and the kidney concentrations of the active metabolite WR-1065 are about 100 times higher than tumour concentrations. To our knowledge, there is no published data in literature presenting acute effect of radioiodine on renal tissue during high dose I-131 radioiodine treatment (RIT). Additionally, it is not known whether amifostine takes role in this process. MATERIALS AND METHODS: In this study, 50 healthy female Wistar albino rats, weighing 200-250 g and averaging 16 weeks old were utilised. The rats were randomly divided into ten groups. 1- Sham group (n=5), 2- Amifostine group (n=5): rats pretreated with 1 cc amifostine (200 mg/kg) by intraperitoneal injection, 3- Radioactive iodine first day group (RI-1) (n=5): rats treated with 1 cc oral 185 MBq radioactive iodine-131 and sacrification performed after 1(st) day, 4- Amifostine + Radioactive iodine first day group (A+RI-1) (n=5): rats pretreated with amifostine (200 mg/kg) by intraperitoneal injection and rats treated with 5mCi radioactive iodine-131 and sacrification performed after 1(st) day. 5- Radioactive iodine third day group (RI-3) (n=5), 6- Amifostine + Radioactive iodine third day group (A+RI-3) (n=5), 7- Radioactive iodine fifth day group (RI-5) (n=5), 8- Amifostine + Radioactive iodine fifth day group (A+RI-5) (n=5), 9- Radioactive iodine seventh day group (RI-7) (n=5) and 10- Amifostine + Radioactive iodine seventh day group (A+RI-7) (n=5). The renal cast formation and tubular damage are evaluated by a pathologist in a blinded manner. RESULTS: Ablative radioiodine-131 therapy induced renal tubular damage was significantly higher in the radioactive iodine fifth day group (RI-5) when compared with the Sham group (p=0.01) and Amifostine group (p=0.01). CONCLUSIONS: A marked ablative radioiodine-131 induced renal toxicity was seen at fifth day of the therapy after a single RIT application and the main histopathological change was tubular damage. Amifostine have protective effects against ablative radioiodine-131 therapy and this effect is significant at fifth day of the therapy.