Underactive thyroid (hypothyroidism)
The thyroid makes too little hormone. A common cause is autoimmune thyroiditis (Hashimoto’s disease). It is usually diagnosed with blood tests for TSH and thyroxine (T4). Possible signs include:
- tiredness and slowness
- weight gain and feeling cold
- dry skin, constipation or low mood
- irregular or heavy periods
Overactive thyroid (hyperthyroidism)
The thyroid makes too much hormone (thyrotoxicosis). Causes include Graves’ disease and thyroid nodules. Possible signs include:
- weight loss despite a good appetite
- a fast or irregular heartbeat
- feeling hot, sweating or shaking
- anxiety, poor sleep, or muscle weakness
An overactive thyroid can occasionally affect the nerves and muscles — the subject of a clinical report Dr. Maiti coauthored.
Goitre and thyroid nodules
A goitre is an enlarged thyroid gland; a nodule is a lump within it. Many are harmless, but they are checked with blood tests and often an ultrasound scan to decide whether any further tests are needed.
Thyroid health in pregnancy
Thyroid hormone levels matter before and during pregnancy. If you have a thyroid condition and are planning a pregnancy or are pregnant, let your doctor know early.
Preparing for your consultation
- recent thyroid blood tests (TSH, T4, T3, antibodies if done)
- ultrasound or scan reports
- a list of all medicines, with doses
- earlier prescriptions
This page gives general information to help you prepare for a consultation. It is not medical advice and does not replace an assessment by a doctor. In an emergency, go to the nearest hospital emergency department. Last updated 25 September 2026.