Overactive thyroid (hyperthyroidism)
Also known as: hyperthyroidism, thyrotoxicosis, Graves' disease
Excess thyroid hormone, most often from Graves' disease, in which antibodies stimulate the thyroid to overproduce.
Overview
Too much thyroxine speeds the body up: weight loss despite appetite, tremor, palpitations, sweating, anxiety and diarrhoea. Graves' disease can also inflame the eye muscles, pushing the eyes forward. Treatment blocks hormone production, destroys thyroid tissue with radioiodine, or removes the gland.
Causes
- Graves' disease (autoimmune, 75%)
- Toxic multinodular goitre and toxic adenoma
- Thyroiditis releasing stored hormone
- Excess thyroxine tablets, amiodarone, iodine loads
Risk factors
- Female sex, age 20 to 50
- Family history
- Smoking (Graves' eye disease)
- Other autoimmune disease
- Recent pregnancy
Symptoms
What a clinician may find
- Fast pulse, atrial fibrillation, tremor, warm moist skin
- Goitre, sometimes with a bruit
- Eye signs: lid retraction, protrusion, double vision
- Weight loss, brisk reflexes
Complications
- Atrial fibrillation and heart failure
- Osteoporosis
- Thyroid eye disease with vision loss
- Thyroid storm (rare, life-threatening)
Diagnosis
Suppressed TSH with raised free T4 or T3; TSH-receptor antibodies confirm Graves'; a radioiodine uptake scan distinguishes causes when antibodies are negative.
Treatment
Beta blockers for symptoms; antithyroid drugs (carbimazole, propylthiouracil) for 12 to 18 months; radioiodine or thyroidectomy for relapse or large goitres, followed by levothyroxine replacement. Eye disease needs specialist care and stopping smoking.
Prevention
Not smoking reduces eye disease; no prevention for the autoimmune process itself.
When to seek care
Urgent care for palpitations with breathlessness or chest pain, fever with confusion and agitation, or sudden vision change or eye pain.