High thyroid radiation dose associated with 131-I-19-iodocholesterol adrenal scanning.
We have examined two patients undergoing 131I-19-iodocholesterol adrenal scans in order to assess thyroidal radiation dose. Thyroid uptakes of 3--5% of the administered 2 mCi dose were found despite prior administration of Lugol's iodine. Analysis of serum samples over a ten day period after iodocholesterol injection indicated that less than 10% of the radioactivity was free iodide. Kinetic results showed a high value for the thyroid/plasma 131I ratio indicating thyroid retention of 131I. This was substantiated by thyroid scintigrams. The thyroid radiation dose was estimated to be 200--250 rad for the two patients. The associated carcinogenic risk is of sufficient magnitude, in our opinion, to warrant regular follow-up of all patients who have undergone 131I-19-iodocholesterol adrenal scanning.
D015071:19-Iodocholesterol / Q000378:metabolism; D000311:Adrenal Glands / Q000000981:diagnostic imaging*; D000328:Adult; D002784:Cholesterol / Q000031:analogs & derivatives*; D005260:Female; D006207:Half-Life; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D011829:Radiation Dosage; D011877:Radionuclide Imaging; D013961:Thyroid Gland / Q000378:metabolism / Q000528:radiation effects*; D013997:Time Factors
D007457:Iodine Radioisotopes; D015071:19-Iodocholesterol; D002784:Cholesterol