OK.
The thyroid gland takes iodine from the circulating blood, combines it with an amino acid, and converts it to the thyroid hormones THYROXIN (T4 — four atoms of iodine) and TRIIODOTHYRONINE (T3 — three atoms of iodine). It stores these hormones until they are released into the boodstream under the influence of thyroid-stimulating hormone — TSH, which comes from the pituitary gland. The vast majority of the hormones released into the bloodstream are bound by proteins, and are INACTIVE — it is the FREE portions (unbound) of the hormones that determines the thyroid status of an individual, affecting metabolism, etc.
So, a typical panel of thyroid tests may include Free T4 (FT4), a T3 uptake (T3U), Total T4, Total T3, Free T3 by RIA, freeT7 (FTI –I’ll explain), and a TSH test.
FTI — This is an index — a mathematical caculation based on the T4 value and the T3 uptake test ( 4 plus 3 is seven? I don’t know where they got the T7 number from.)
When you get your lab results back, the lab will print out the “normal” range of values for each test, and indicate whether your result is in range or out of range, and if out of range, whether it is “high” or ‘low”. You doctor can give you a copy of these test results, to help you out.
If you want more information about any of the tests, let me know. I have a laboratory manual of diagnostic tests that I can look in for more specific information.
Bobbi