Follow-up thyroid carcinoma by whole-body counting.

Abstract

Abstract A simple whole-body counter has been used to measure retention of 131I following a test dose in 36 patients with thyroid carcinoma in whom normal thyroid tissue had been ablated. (1) In patients with normal renal function, the fall of wholebody 131I content occurred with a fast initial component (biological half-life, T½≏12 hours) due to iodide excretion. In all patients, even in the absence of detectable localised 131I concentration, this was followed by a much slower component (T½ > 14 days). The size of the latter component depended on the amount of 131I that was organically bound and provided a measure of the amount of 131I-concentrating tissue remaining. (2) In patients with normal renal function, a single measurement on the sixth day after the test dose indicated the magnitude of the slow component. A retention exceeding 0·31 per cent of the dose at the sixth day was associated with localised residual 131I-concentrating tissue, while with retention less than 0·15 per cent no such tissue was...