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Thyroid function tests
Make it clearer
Thyroid function tests are blood tests. They may measure TSH, T4, and T3, and some evaluations also include thyroid antibodies. Each name refers to a different signal or product within the system.
TSH does not come from the thyroid. It is made by the pituitary gland in the brain and tells the thyroid how much T4 and T3 to produce. Picture a communication circuit: the pituitary sends a signal, and the thyroid answers with hormones. Measuring at different points along that circuit helps describe how the regulation is working. That is not the same as explaining every function of the gland or interpreting one person's result.
In brief
Thyroid function tests are blood tests that may measure TSH, T4, and T3; some evaluations also include thyroid antibodies.
TSH is produced by the pituitary gland and tells the thyroid how much T4 and T3 to make, so measuring it provides information about the regulatory circuit, not just the thyroid in isolation.
The pituitary sends the TSH signal, and the thyroid responds by producing T4 and T3; the tests sample different points along that circuit.
Sources (1)
- National Institute of Diabetes and Digestive and Kidney DiseasesThyroid Tests
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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