Biological half-time of tritiated water: comparison of hyperthyroid and hypothyroid patients.

The half-time values of tritiated water were explored in eleven hyperthyroid patients and in two hypothyroid ones. For reasons of comparability the numbers are expressed in days per square meter (d/m2) of body surface. Against the estimated 5.4 d/m2 in normal subjects, the hyperthyroids reflected 3.9 +/- 0.66 and the two determinations on hypothyroids were 6.42 and 7.13, respectively. During the study neither diagnostic nor therapeutic procedures were ever postponed. The half-time values are not representative of extreme conditions in hyper- or hypothyroids, but are sufficiently clear to indicate well-defined differences from normal people. The total exposure to radiation for the exploratory procedure was minimal, estimated at less than 12 mrem for the normal standard man.