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Feb 27, 2014 · High levels of TBG could be caused by high levels of T3 and T4 because TBG is a carrier protein that binds T3 and T4 together in the bloodstream. High levels of TBG indicate a possible overactive thyroid gland (Ticchio 2008). Undetectable levels of TSH could also result in hyperthyroidism (Spencer et al 1987). ................
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