Radioiodine dosimetry in patients with end-stage renal disease receiving continuous ambulatory peritoneal dialysis therapy

In patients with end-stage renal disease (ESRD), (NaI)-I-131 dosages for th yroid cancer may have to be reduced to avoid excess radiation doses to red marrow, because radioiodine is primarily excreted by kidneys. In ESRD patie nts receiving continuous ambulatory peritoneal dialysis (CAPD) therapy (thr ee to five 2-L exchanges daily) creatinine clearance rates are very low (me an, 7 mL/min), and radioiodine clearance rates may be proportionately reduc ed. Thus, radioiodine kinetic studies were performed in two hypothyroid CAP D patients with thyroid cancer, in eight euthyroid CAPD patients, and in ei ght thyroid cancer patients with normal renal function. AU received (NaI)-I -131 or (NaI)-I-123 orally, with serial blood, urine, and/or dialysate samp ling for 24-70 h. Dosimetry calculations were performed using the MIRDOSE3 computer program. In CAPD patients, serum radioiodine half-times were 5 times longer, and rad ioiodine clearance rates by urine plus dialysate were 20% of those in patie nts with normal renal function. (NaI)-I-131 dosages for the two CAPD patien ts with thyroid cancer were reduced from 150 mCi [5.6 gigabecquerels (GBq)] to 26.6 mCi (0.98 GBq) and 29.9 mCi (1.11 GBq), respectively, resulting in radiation doses to red marrow and total body comparable to those in patien ts with normal renal function who received a mean of 148 mCi (5.5 GBq) (NaI )-I-131. Thus, in patients receiving continuous ambulatory peritoneal dialy sis therapy, 5-fold reductions in radioiodine clearance rates require 5-fol d decreases in (NaI)-I-131 dosages to avoid excessive radiation doses to to tal body and red marrow.