Hyperthyroidism

Hyperthyroidism means an increase in the amount of circulating thyroid hormones (T3 & T4) in the body. This condition leads to thyrotoxicosis which represents the symptoms and signs which occurs due to increased thyroid hormones.
Hyperthyroidism can occur due to an autoimmune disease such as Graves' disease, a toxic hyperfunctioning goitre or solitary nodule, due to medications such as lithium, secondary to pituitary tumours in the brain, due to an inflammatory process (thyroiditis), ectopic thyroid tissue or rarely due to thyoid cancers.
The common symptoms of thyrotoxicosis are: sweating, palpitations, irritability, heat intolerance, weight loss, increased appetite, increased bowel movements, impaired fertility, reduced libido, hyperactivity and insomnia. Signs associated with thyrotoxicosis are an irregular, rapid pulse, tremor, warm moist skin, muscle weakness, enlargement of the male breast tissue and goitre.
Diagnosis of hyperthyroidism is made in the presence of the symptoms and signs of thyrotoxicosis with a confirmatory blood investigation for raised levels of serum T3 and T4. Then, the cause for the hyperthyroidism should be investigated. Usually an ultrasound of the neck is done to assess the goitre.
Patients with Graves' disease will also have specific signs for the disease such as protruded eyeballs (proptosis), swelling around the eyes (periorbital oedema), limited eyeball movement (extraocular muscle involvement), deterioration of vision and swelling of the lower limb skin (pretibial myxoedema). Blood investigations for anti-thyroid peroxidase and anti-thyroglobulin antibodies are diagnostic.
Treatment of hyperthyroidism is aimed at reducing the levels of thyroid hormones and also reducing the sympathetic activity for control of symptoms. Two drugs commonly used to reduce thyroid hormones are propylthiouracyl and carbimazole. Both these drugs reduce the production of thyroid hormones in the body. Propanolol, a beta-blocker commonly used in hypertension, is used for symptomatic control in patients with thyrotoxicosis.
Radioactive iodine ablation of the thyroid gland can also be used as a first line treatment of thyrotoxicosis. Thyroid follicular cells are destroyed by the radiation emitted. However, this is contraindicated in patients who are pregnant, breastfeeding, who plan to get pregnant within 6 months or who are in contact with children.
Surgery (thyroidectomy) is indicated in patients with large goitres, patients who are contraindicated for radioiodine ablation and patients who wish to have their thyroids removed. This is considered as the definitive treatment for thyrotoxicosis. Patients will have to be started on anti-thyroid medications prior to surgery to reduce the risk a thyroid storm which can be deadly. The risks and complications of thyroid surgery will be discussed in the next article.