TSH - as the name suggest - stimulates the thyroid gland to produce thyroxine which, after some steps controls metabolism.
The steps (simplified)
- Brain receives negative feedback: not enough
- pituitary gland releases TSH
- Thyroid gland receives TSH and starts producing thyroxine
- thyroxine is converted to triiodothyronine (mostly in the liver)
- triiodothyronine controls growth, metabolism, body temp, heart rate, and more.
As a biomarker
TSH is (often) received in µIU/mL (micro International units per milliliter).
Ref range
For adults between 0.3 µIU/mL and 3 µIU/mL is considered normal. However, actual ranges are very individual for seemingly no reason. So being within this range does not necessarily indicate good “health”.