Your thyroid gland produces hormones that regulate growth and energy expenditure. Thyroid disorders are quite common, and many people don’t have any symptoms at all. This thyroid test screens for the thyroid hormones that play a key role in regulating the body’s metabolism.
Communicates with the thyroid gland to produce T3 and T4 which regulate metabolic functions. High TSH thyroid test levels indicates an underactive thyroid, and low levels an overactive thyroid.
Measures the thyroxine that is freely circulating and able to regulate metabolism. High FT4 thyroid test levels indicate an overactive thyroid, and low levels an underactive thyroid.
Measures the triiodothyronine that is freely circulating. High FT3 thyroid test levels indicate an overactive thyroid, and low levels an underactive thyroid.
Reverse T3 (rT3) is virtually inactive having only 1% the activity of T3 and blocks the action of T3 acting as a metabolic break. Normal metabolism of T4 requires the appropriate balance of T3 to rT3. If the proportion of rT3 dominates then it will antagonise T3 thus producing hypothyroid symptoms despite sufficient circulating levels of T4 and T3.
Reverse triiodothyronine is an isomer of triiodothyronine (T3) which blocks its action.
A low FT3 to Reverse T3 ratio can indicate reverse T3 dominance.
Download and print your pathology form from your i-screen dashboard.
Take your form to one of our affiliated collection centres to have your sample taken.
You do not need to fast for this blood test.