Guest guest Posted June 21, 2009 Report Share Posted June 21, 2009 Free thyroxine (T4) can be measured directly (FT4) or calculated as the free thyroxine index (FTI). The FTI tells how much T4 is present compared to the thyroxine-binding globulin. The FTI can help tell if abnormal amounts of T4 are present because of abnormal amounts of thyroxin-binding globulin. T7 is a convenient parameter that accounts mathematically for the reciprocal effects of T4 and T3 uptake to give a single figure which correlates with free T4. Therefore, increased FTI is seen in hyperthyroidism, and decreased FTI is seen in hypothyroidism. Early cases of hyperthyroidism may be expressed only by decreased thyroid stimulation hormone (TSH) with normal FTI. Quote Link to comment Share on other sites More sharing options...
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