Hemodialysis in a Patient Being Treated with ¹⁵³Sm

TO THE EDITOR:

We recently treated a 79-y-old, 53.6-kg woman with 1,558 MBq (42.1 mCi) ¹⁵³Sm for bone pain palliation secondary to breast metastases. In consultation with Burlex Laboratories, Inc., the supplier of ¹⁵³Sm, the dose was lowered to 27.75 MBq/kg (0.75 mCi/kg) to take into account the lack of renal excretion. The package insert indicates 34.5% ± 15.5% excretion in the urine in the first 6 h. The patient was having dialysis at an outpatient clinic. We were unable to find any information from the supplier or in the literature on the amount of radioactivity to expect in the blood and dialysate at the time of the next treatment, which was scheduled to be 44 h after administration of the ¹⁵³Sm. On learning that the patient’s blood and dialysate might be radioactive, the clinic did not wish to provide subsequent dialysis treatment. The patient therefore was referred back to the hospital. This provided the opportunity to measure the blood and dialysate radioactivity concentrations. Fifteen minutes after the administration of the radiopharmaceutical, a blood sample was obtained for the initial blood concentration. When the patient returned 44 h later, a blood sample and a sample of the dialysate were obtained. Samples were counted in a well counter with a pulse height analyzer window encompassing the 100-keV photopeak. The decay-corrected blood concentration at 44 h was 0.23% and that of the dialysate was 0.05% of the initial blood concentration. The slightly contaminated disposable portions of the dialysis equipment were stored for decay.