Parathyroid scans and thyroid uptake of thallium 201 of subjects in chronic hemodialysis

Patients in chronic hemodialysis were injected i.v. 1mCi each Thallium Chloride 201 (TlCl) and Technetium 99m pertechnetate (Tc99m) and imagings of the thyroid and parathyroid glands were taken after 30, 60 and 90'. Parathyroid scans were obtained by computerized subtraction of the Tc99m from the TlCl image. The percentage uptake of TlCl and Tc99m was measured at 1 and 3 hrs in normal, hemodialyzed and thyroxine treated subjects as well as in untreated and thyroxine treated mice. Thyroid tests and serum electrolytes were routinely determined. Enlarged parathyroid glands were visualized in 5 out of 6 patients on hemodialysis. TlCl uptake was greatly decreased and thyroid imagings poor in patients in renal failure. This was parallel in all cases with a high serum K/sup +/. Tc99m uptake and scans were unaffected by renal status. Administration of L-thyroxine greatly reduced the thyroidal uptake and accompanying scans after both Tc99m and TlCl in human subjects as well as in experimental animals. The authors conclude the following: a) TlCl - Tc99m subtraction scans enabled visualization of hyperplastic parathyroid glands in patients in chronic hemodialysis; b) Thyroid uptake of TlCl was inversely related to the serum K/sup +/ level; and c) Both Tc99m and TlCl thyroidal uptake were inhibited by administration of L-thyroxine, hence TSH dependent