Q3.

What is TT3?

The ration in serum that T3 connected with protein is 99.7%. The normal range of TT3 is from 1.2 to 3.2nmol/L, it is also affected by TBG. The concentration of TT3 changes parallel with TT4. But in the early period or early recrudescence period of hyperthyroidism, TT3 increased very quickly, about 4 times than the normal; TT4 increased a little bit slowly, only the 2.5 times than the normal. Therefore, TT3 is referred to be the index to diagnose if hyperthyroidism is sensitive or not, especially in the early period of this disease and in the observation period of the treatment or to be the aura of the recrudescence. TT3 will also not be very high when patients are in old age or with long time hyperthyroidism history.

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