Metabolism
Pituitary gland
Thyroid-Stimulating Hormone (TSH)
The pituitary's signal telling the thyroid how much hormone to make.
What it does
- Stimulates the thyroid to produce T3 and T4
- Used as the main blood test for thyroid function
Too much
- High TSH usually means an underactive thyroid (the body pushing it to work harder)
Too little
- Low TSH usually means an overactive thyroid or too much thyroid medication
Keeping it balanced: TSH is the routine screen for thyroid problems — discuss abnormal results with a doctor.
Sources & references
Think a hormone may be out of balance?
The symptoms of hormonal excess and deficiency are non-specific — tiredness, weight change, low mood and poor sleep have many everyday causes. No hormone problem can be self-diagnosed from a symptom list.
Diagnosis needs blood tests interpreted alongside your history, sometimes repeated at set times of day because many hormones vary hour to hour. Speak to a GP if symptoms are persistent; seek urgent care for severe symptoms such as confusion, fainting, chest pain or extreme thirst with frequent urination.
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