Free Thyroxine T4 Levels. There have been studies suggesting that higher levels of free t 4 in the blood may be associated with an increased risk of developing a solid cancers (for example, lung, breast, prostate, gastrointestinal (gi) cancers). High levels of any of these tests (total t4, free t4, or free t4 index) may indicate an overactive thyroid, also known as hyperthyroidism.
Excess of it in any tests indicates the thyroid disorder. Associated with the protein in the blood; Most patients will feel well in that circumstance.
When combined with an elevated tsh level, a normal free t4 may indicate subclinical hypothyroidism.
Your free t4 levels can give you amazing insight into how well your thyroid is functioning, but you need to remember that they are only a small piece of an even larger puzzle. However, changes in binding proteins can occur which affect the level of total t4 but leave the level of unbound hormone unchanged. This is also called hyperthyroidism. What does it mean if t4 levels are abnormal?