Free Thyroxine Index Normal Range. In abnormal cases like hyperthyroidism, the value is greater than 8.0 µg%. Similarly, in the case of hypothyroidism, the serum value falls below 3 µg%.
The correlation was almost as high as that of the free thyroxine (t4) index with fr. In most cases, free thyroxine (also known as free t4) is good indicator of thyroid function, along with tsh and other measures. Free thyroxine (free t4) optimal range:
The free thyroxine index (fti) is determined by the following calculation:
Similarly, in the case of hypothyroidism, the serum value falls below 3 µg%. Interassay precision (cv) is <5%. Similarly, in the case of hypothyroidism, the serum value falls below 3 µg%. Replacement thyroxine therapy is often associated with increased t4 and free t4 and normal concentrations of t3.
