Hyperthyroidism

Author: Dr Shendy Engelina, Core Medical Trainee, Northampton General Hospital, UK. Chief Editor: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, April 2016.

Introduction

Abnormal levels of circulating thyroid hormone (thyroxine) and underlying diseases may lead to alterations in the appearance of skin, hair and nails. The thyroid gland can be overactive, resulting in hyperthyroidism, discussed here, or underactive, resulting in hypothyroidism.

What is hyperthyroidism?

Hyperthyroidism is due to excessive thyroxine. It is also known as thyrotoxicosis. It can lead to a variety of signs and symptoms.

Who gets hyperthyroidism?

Hyperthyroidism:

What causes hyperthyroidism?

There are several causes for hyperthyroidism.

Graves disease

Graves disease is the most common cause of hyperthyroidism (80%).

Thyroid nodule or nodules

A thyroid nodule is a benign growth within the thyroid gland.

Medications

Hyperthyroidism arises from:

Subacute thyroiditis

Subacute thyroiditis is also known as De Quervain thyroiditis.

Rare causes of hyperthyroidism

Rare causes of hyperthyroidism include:

What are the clinical features of hyperthyroidism?

Hyperthyroidism results in an increase in the body’s metabolic rate, which characterised by:

Other common systemic features include palpitations, tremor, weight loss, heat intolerance, anxiety and menstrual disturbance (irregular or light period).

Graves disease may also cause thyroid dermopathy resulting in pretibial myxoedema and exophthalmos, which are associated with the presence of thyroid antibodies.

What are the complications of hyperthyroidism?

Untreated hyperthyroidism can cause serious systemic complications including:

Medical emergencies associated with hyperthyroidism include thyroid storm and thyrotoxic periodic paralysis.

Thyroid storm

Thyroid storm is also called thyroid crisis.

Thyrotoxic periodic paralysis

Thyrotoxic periodic paralysis is characterised by acute onset of hypokalaemia.

How is hyperthyroidism diagnosed?

Hyperthyroidism is diagnosed by thyroid function tests (TFTs).

Interpretation of thyroid function tests
TSHFree T4 (thyroxine)Free T3 (triiodothyronine)
(Primary) hyperthyroidism Low High High
Secondary hyperthyroidism High High High
Subclinical hyperthyroidism Low Normal Normal
Primary hypothyroidism High Low Low or normal
Secondary hypothyroidism Low or normal Low Low or normal
Subclinical hypothyroidism Borderline high Normal Normal
Sick euthyroid syndrome Low Low Low

Serum autoantibodies are markers of autoimmune disease. They should include:

Full blood count and inflammatory markers, such as C-reactive protein, are routinely included to screen for anaemia (commonly associated with hyperthyroidism) and systemic infection causing thyroiditis.

Imaging should include:

What is the treatment for hyperthyroidism?

Hyperthyroidism is either treated with medication, by radioactive iodine, surgery or a combination of these.

Anti-thyroid medication

Radioactive iodine

Radioactive iodine is usually indicated for relapses of Graves disease and toxic nodular goitre. However, it has increasingly been used as first-line treatment for hyperthyroidism in teenagers.

Surgery

Partial or total thyroidectomy is surgical removal of part or the whole of the thyroid gland respectively.

What is the outcome for hyperthyroidism?

Treatment of hyperthyroidism is usually effective. Regular thyroid function tests are recommended following successful treatment, as some individuals develop further relapses, with annual blood tests long term.

Related information

Email Newsletter

Would you like to receive our dermatology updates by email?

SIGN UP

Submit your images

We're seeking high-quality photos of skin diseases.  

SUBMIT A PHOTO

Machine diagnosis

Watch DermNet's proposal to create a 'Skin Disease Image Recognition Tool' - winner of the 2017 'Clinicians' Challenge Active Award' by the NZ Ministry of Health and HiNZ.

Subscribe to our mailing list

* indicates required
DermNet NZ Newsletter