Absorbed dose to the human adrenals from lodomethylnorcholesterol (I-131) "NP-59": concise communication.

During the past 2 years, adrenal uptake percentage values were measured in more than 40 patients, using an external counting technique. They suggest that the absorbed dose to the adrenals is significantly less than 150 rads/mCIi previously estimated using concentration values from animal adrenals. The measured combined uptake percentage for both adrenals ranged from 0.15% to 0.52% in 21 patients without evidence of adrenal disease, with a mean of 0.33% +/- 0.1%; also from 0.22% to 1.5% in 22 patients with Cushing's disease, with a mean uptake of 0.78% +/- 0.35%. The absorbed dose to the adrenals was estimated to be 25 rads/mCi for patients without evidence of adrenal disease, and 57 rads/mCi for patients with Cushing's disease. Both values are calculated for the respective mean uptake percentages by using MIRD formalism.