Hyperthyroidism

Also called Overactive thyroid, Graves' disease, Thyrotoxicosis

A thyroid running too fast. Often mistaken for anxiety, and it can trigger dangerous heart rhythms.

What it is

Hyperthyroidism is the opposite of hypothyroidism: too much thyroid hormone, so everything runs fast. It affects around 2% of women and 0.2% of men.

Graves' disease, an autoimmune condition, is the commonest cause. Toxic nodules are the next.

It gets misdiagnosed as an anxiety disorder with striking regularity, because the presentation is a racing heart, restlessness, sweating, tremor and difficulty sleeping. People are prescribed treatment for panic while their thyroid runs unchecked.

In older people it presents differently and more quietly: sometimes only as atrial fibrillation, weight loss, or apathy.

Signs you might notice

Weight loss despite a good or increased appetite.

A racing or irregular heartbeat. Tremor. Sweating and heat intolerance.

Anxiety, irritability, and difficulty sleeping.

Frequent bowel movements. Muscle weakness, particularly in the thighs.

In Graves' disease: bulging eyes, gritty or double vision, and a swelling in the neck.

Thyroid eye disease can progress even after the thyroid itself is treated, and it needs its own specialist attention.

How it can affect day-to-day life

The cardiac risk is the one to take seriously. Untreated hyperthyroidism causes atrial fibrillation, which causes stroke, and it accelerates bone loss towards osteoporosis.

Thyroid storm is rare and life-threatening: fever, severe agitation or confusion, a very fast heart rate and vomiting, usually triggered by infection or surgery in someone untreated.

Treatment options each carry consequences: antithyroid drugs, radioiodine, or surgery, and after the last two most people become hypothyroid and need lifelong replacement.

Supporting someone well

Ask for a thyroid blood test before accepting an anxiety diagnosis in anybody with palpitations, weight loss and tremor. This is the single most useful line here.

Take antithyroid medication exactly as prescribed, and know the warning: a sore throat, mouth ulcers or fever on carbimazole needs an urgent blood count, because it can suppress white cells.

Never smoke with thyroid eye disease. Smoking dramatically worsens it and stopping is the most effective single measure.

Attend the monitoring blood tests. Doses change frequently in the first year.

After treatment, watch for the swing into hypothyroidism, which is common and easily missed.

Where to get help

A GP can diagnose with blood tests and should refer to an endocrinologist.

British Thyroid Foundation and the Thyroid Eye Disease Charitable Trust both provide reliable information.

Fever with confusion and a racing heart in somebody with hyperthyroidism is an emergency.