RT Journal
A1 Wortsman J, Soler NG
T1 TRiiodothyronine levels-reply
JF Archives of Internal Medicine
JO Archives of Internal Medicine
YR 1979
FD November 1
VO 139
IS 11
SP 1320
OP 1320
DO 10.1001/archinte.1979.03630480091042
UL http://dx.doi.org/10.1001/archinte.1979.03630480091042
AB In Reply.— 
    My co-workers and I agree with Hydovitz et al regarding the uncertainty associated with the use of total T3 (radioimmunoassay) for predicting the outcome of sodium iodide I 131 therapy in hyperthyroidism. Our study was actually prompted by the suggestion that the isolated increase in the level of T3 would be an early marker of recurrence of the hyperthyroidism. Prolonged follow-ups and repetition of the determinations did not bear this out.Our report did not address the question of the mechanism for the increase in the T3 levels. Calculation of the free hormone levels would be an obvious step in that direction; better yet is the direct determination of free thyroid hormone. Nevertheless, there are also pitfalls in this determination, such as interference by free fatty acids,1 and possibly by triglycerides (I. J. Chopra, J. Wortsman, N. G. Soler, unpublished data, March 1978). Even