Feature Article

A guide to thyroid dysfunction

Ann McCormack, Diana L Learoyd
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Thyroid dysfunction is common but can present both diagnostic and management challenges. This article will present a practical approach to patients with hyperthyroidism and hypothyroidism.

Key Points

  • Thyroid dysfunction is common in the community. The prevalence of hyperthyroidism is approximately 1 to 2% and hypothyroidism 5 to 10%, with a strong female predominance.
  • Graves’ disease is the most common cause of hyperthyroidism. Other causes include a toxic multinodular goitre, toxic adenoma and thyroiditis.
  • A technetium-99m nuclear thyroid uptake scan and measurement of thyroid receptor antibodies are the most useful initial investigations for determining the cause of hyperthyroidism, if it is not clinically apparent.
  • Treatment of hyperthyroidism usually involves antithyroid drugs (carbimazole or propylthiouracil), radioactive iodine or total thyroidectomy.
  • The presence of autoimmune thyroid disease (Hashimoto’s thyroiditis), which is the most common cause of hypothyroidism, is confirmed by the presence of antithyroglobulin and/or antimicrosomal (antithyroid peroxidase) antibodies.
  • Careful up-titration of thyroxine dose is usually required in treatment of hypothyroidism.
  • Thyroid dysfunction in pregnancy is an important clinical scenario and requires specialist involvement.
  • Treatment of subclinical thyroid dysfunction is controversial.