TSH (Thyroid-Stimulating Hormone)
Also known as: TSH, Thyrotropin
TSH (thyroid-stimulating hormone) is made by your pituitary gland and signals your thyroid to produce thyroid hormones. It acts a bit like a thermostat for your thyroid system.
Why it's measured
TSH is the most common first test of thyroid function. Because of the thermostat-like feedback loop, TSH often moves in the opposite direction to thyroid hormone levels, which is why doctors interpret it carefully.
Typical range
Many labs use a reference range of roughly 0.4 to 4.0 mIU/L, though ranges vary by lab and can differ by age, pregnancy, and other factors. Your doctor interprets your value within your specific situation.
What high values can mean
A higher TSH is one pattern doctors examine when evaluating thyroid function, sometimes alongside additional thyroid tests. It is not a diagnosis on its own.
What low values can mean
A lower TSH is another pattern doctors look at, again usually together with other thyroid markers and your symptoms before drawing conclusions.
Questions to ask your doctor
- Does my TSH need any follow-up thyroid testing, like Free T4?
- Could any medications or my overall health be affecting this?
- How often should my thyroid be monitored?
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Try the explainerEducational information only — not medical advice, diagnosis, or treatment. Reference ranges vary by lab; always use your own lab's range and discuss results with a qualified clinician.