TG and neoplasm: After 1947, the radionuclide used was likely always 131I. It was recognized that 131I uptake of remnant tissue and differentiated tumor was augmented when in addition to removal of the bulk of the normal thyroid tissue, 131I uptake of residual tissue and tumor was stimulated when the patient was hypothyroid; that is deprived of thyroid hormone producing elevation of serum throid-stimulating hormone (TSH)-although this assay was not routinely available for many years.