Thyroid dysfunction is common and can range in severity from asymptomatic to life-threatening. It is important for health practitioners to understand the blood tests and imaging required to determine the cause of thyroid dysfunction.
- The initial screening test for thyroid dysfunction is measurement of thyroid stimulating hormone (TSH) level, followed by measurement of free thyroxine (T4) and free tri-iodothyronine (T3) if the TSH level is abnormal.
- TSH receptor antibodies should be measured in all patients with hyperthyroidism to assess for Graves’ disease; antithyroid peroxidase antibodies and antithyroglobulin antibodies are associated with autoimmune (Hashimoto’s) thyroiditis but not specific.
- A technetium-99m thyroid isotope scan is useful to clarify the cause of hyperthyroidism if this is unclear, and thyroid ultrasound examination is useful to assess thyroid structure if there are abnormalities on clinical examination.
- Subclinical thyroid dysfunction does not always warrant treatment and clinicians should be familiar with the current indications for therapy.
- Thyroid dysfunction during pregnancy requires special care, and specialist referral is appropriate.