The thyroid gland — a small butterfly-shaped gland in the neck — produces hormones that regulate metabolism, energy, heart rate, and many other body functions. Thyroid disorders are very common in the UK, affecting approximately 1 in 20 people, and are more common in women. Conditions range from an underactive thyroid (hypothyroidism) to an overactive thyroid (hyperthyroidism) and thyroid cancer.
Hypothyroidism (Underactive Thyroid)
Hypothyroidism occurs when the thyroid gland doesn’t produce enough thyroid hormones (T3 and T4). This causes the body’s functions to slow down. It affects around 2% of the UK population, most commonly women over 40.
Symptoms of Hypothyroidism
- Tiredness and fatigue
- Weight gain despite no change in diet
- Feeling cold all the time
- Depression or low mood
- Slow movements and thoughts
- Muscle aches and weakness
- Constipation
- Dry skin and hair loss
- Heavy or irregular periods
- Puffy face, hands, and feet
- Slowed heart rate (bradycardia)
- Hoarse voice
Causes of Hypothyroidism
- Autoimmune thyroiditis (Hashimoto’s disease) — the most common cause; the immune system attacks the thyroid gland
- Previous thyroid surgery or radioiodine treatment
- Iodine deficiency (rare in the UK)
- Certain medications (lithium, amiodarone)
- Congenital hypothyroidism (born with an underactive thyroid)
NHS Treatment for Hypothyroidism
Hypothyroidism is treated with levothyroxine — a synthetic thyroid hormone tablet taken once daily. Most people need to take this for life. The dose is adjusted based on regular TSH blood tests. Symptoms typically improve within a few weeks of starting treatment, though it may take months to feel completely well.
Hyperthyroidism (Overactive Thyroid)
Hyperthyroidism occurs when the thyroid produces too much thyroid hormone, causing body functions to speed up. It affects around 1 in 100 people in the UK, with women 10 times more likely to develop it than men.
Symptoms of Hyperthyroidism
- Nervousness, anxiety, and irritability
- Unexplained weight loss
- Rapid or irregular heartbeat (palpitations)
- Feeling hot and sweating excessively
- Diarrhoea
- Tiredness and muscle weakness
- Trembling hands
- Difficulty sleeping
- Swelling in the neck (goitre)
- Eye problems (bulging eyes in Graves’ disease)
- Light or irregular periods
Causes of Hyperthyroidism
- Graves’ disease — an autoimmune condition; the most common cause in the UK
- Thyroid nodules (lumps) producing excess hormone
- Thyroiditis (inflammation of the thyroid)
- Excess iodine intake
NHS Treatment for Hyperthyroidism
- Antithyroid drugs — carbimazole or propylthiouracil (PTU) reduce thyroid hormone production; taken for 12–18 months
- Radioiodine treatment (RAI) — a one-off radioactive iodine capsule that destroys part of the thyroid; often results in hypothyroidism requiring levothyroxine
- Beta-blockers — e.g. propranolol, used to relieve rapid heartbeat and tremors while other treatments take effect
- Surgery (thyroidectomy) — surgical removal of part or all of the thyroid; considered if other treatments are unsuitable
Thyroid Nodules and Goitre
A goitre is an enlarged thyroid gland. It can occur with underactive, overactive, or normal thyroid function. Thyroid nodules (lumps) are very common — most are benign. Any new neck lump should be assessed by a GP. Investigation may include blood tests, ultrasound scan, and fine needle aspiration (FNA) biopsy if needed.
Thyroid Cancer
Thyroid cancer is relatively uncommon in the UK (around 4,500 new cases per year) but has high survival rates when diagnosed early. The most common types are:
- Papillary thyroid cancer — the most common type (80%); grows slowly and responds well to treatment
- Follicular thyroid cancer — the second most common; also highly treatable
- Medullary thyroid cancer — can be hereditary; associated with MEN2 syndrome
- Anaplastic thyroid cancer — rare and aggressive; requires urgent specialist care
Symptoms may include a painless lump in the neck, swollen lymph nodes, hoarseness, and difficulty swallowing. Treatment involves surgery, followed by radioiodine, radiotherapy, or targeted drug therapy depending on the type and stage.
Thyroid Blood Tests: Understanding TSH, T3, T4
| Test | Normal Range | What It Means |
|---|---|---|
| TSH (Thyroid Stimulating Hormone) | 0.4–4.0 mIU/L | High TSH = underactive thyroid; Low TSH = overactive thyroid |
| Free T4 | 9–24 pmol/L | Low T4 with high TSH confirms hypothyroidism |
| Free T3 | 3.5–7.8 pmol/L | Elevated in hyperthyroidism |
| Thyroid antibodies (TPO, TRAb) | Negative | Positive in Hashimoto’s or Graves’ disease |
Living Well with a Thyroid Condition
- Take levothyroxine on an empty stomach, 30–60 minutes before food or other medications
- Attend regular blood test monitoring (usually every 6–12 months once stable)
- Be aware that certain foods and supplements (calcium, iron, soy) can affect levothyroxine absorption
- Report any new symptoms to your GP — your dose may need adjusting
- Join support groups such as the British Thyroid Foundation for peer support and information
Related Health Guides on YourHealthXpert
Explore these related NHS-aligned health guides:
- Anxiety & Depression Guide — Thyroid dysfunction — both hypo and hyperthyroidism — causes significant mood disturbances that are often mistaken for primary mental health conditions.
- Heart Attack Guide — Untreated hypothyroidism raises cholesterol and cardiovascular risk; hyperthyroidism causes AF; learn the NHS cardiac monitoring approach in thyroid disease.
- Osteoporosis Guide — Hyperthyroidism and excess levothyroxine both reduce bone density; understand the NHS guidance on thyroid treatment and bone protection.
- Menopause Guide — Thyroid disorders and menopause share overlapping symptoms including fatigue, mood changes and weight gain; learn how to distinguish them.
- High Blood Pressure Guide — Thyroid imbalances directly affect blood pressure; understand how thyroid treatment improves cardiovascular risk in NHS care.
- High Cholesterol Guide — Hypothyroidism is a reversible secondary cause of high cholesterol; learn why thyroid testing is recommended before starting statins.