Thyroid Function Tests (TFTs) - Interpretation

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Age*
Sex*		Pregnant

Component	Value
Thyroid Stimulating Hormone (TSH)
Free T4 (thyroxine) (FT4)
Free T3 (triiodothyronine) (FT3) [Coming soon]

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The thyroid gland makes two major hormones, which are secreted into the bloodstream. These thyroid hormones are thyroxin (T4) and triiodothyronine (T3). T4 contains four iodine atoms. T4 is converted to triiodothyronine (T3), which contains three iodine atoms. The amount of T4 and T3 secreted by the thyroid gland is regulated by the pituitary gland. The pituitary gland determines the level of thyroid hormones in the blood and secretes thyroid stimulating hormone (TSH), which regulates the amount of T4 and T3 in the body.

Thyroid function tests (TFTs) or thyroid panel usually includes thyroid stimulating hormone (TSH), thyroxine (T4) and triiodothyronine (T3). Also, a "free" portion of T4 and T3 can be measured (free T4 (FT4) and free T3 (FT3)).

The normal range for TSH (or TSH reference values) is usually 0.4-4.0 mU/L (milliunits per liter). TSH levels in children are higher than in adults. The normal range for TSH during pregnancy is slightly shifted downward.