TSH and thyroid hormone feedback
Biomarker library
Thyroid Health
TSH
TSH (thyroid-stimulating hormone) is the pituitary gland's message to your thyroid: make more hormone.
Measured in your health assessment, with a doctor to explain your result. Book yours
Why it matters
It works like a thermostat. When thyroid hormone runs low the pituitary turns TSH up, and when it runs high TSH falls. That makes TSH the most sensitive first test of thyroid function, often changing before thyroid hormones leave their normal range.
What a result can mean
Lower than the range
A low TSH usually means an overactive thyroid (hyperthyroidism), as in Graves' disease, causing weight loss, anxiety, palpitations and feeling hot. Taking too much thyroid medicine, and some other medicines, can also lower it.
Higher than the range
A raised TSH usually means an underactive thyroid (hypothyroidism), most often from the autoimmune condition Hashimoto's thyroiditis. It can cause tiredness, weight gain, feeling cold and constipation. Mild rises are sometimes temporary, for example after an illness.
What can help
An underactive thyroid is treated with levothyroxine tablets, adjusted using TSH. An overactive thyroid is treated with medicines, radioactive iodine or surgery. Borderline results are usually repeated, often with thyroid antibodies.
Read it with
NoteGeneral educational illustration. Colours, sizes and movement are simplified. This is not a scan or a simulation of your body. General information, not personal medical advice: a doctor reads your own results with your history.
Know your TSH.
Measured in your health assessment and explained by the doctor who reviews your results.