Hypothyroidism, or an underactive thyroid, is a prevalent health condition in Australia that affects the body’s ability to produce enough thyroid hormones. These hormones are essential for regulating metabolism, energy levels, and overall bodily functions. Understanding the various causes of hypothyroidism is key to early diagnosis and effective management. Here’s a comprehensive look at what leads to hypothyroidism in the Australian context.
The Leading Cause: Hashimoto’s Disease
The most common cause of hypothyroidism in Australia is Hashimoto’s thyroiditis, an autoimmune disorder. In this condition, the immune system mistakenly attacks the thyroid gland, producing antibodies that damage thyroid cells. This immune attack causes inflammation and gradual destruction of the gland, reducing its ability to produce hormones. Hashimoto’s disease often results in swelling of the thyroid (goitre) but can also cause the gland to shrink over time.
Other Causes of Hypothyroidism
While Hashimoto’s disease dominates as the primary cause, several other factors contribute to hypothyroidism in Australia:
- Thyroid Surgery: Removal of part or all of the thyroid gland, often performed to treat nodules, cancer, or hyperthyroidism, can lead to reduced hormone production.
- Radiation Therapy: Treatments targeting the head and neck area, including radioactive iodine therapy used for overactive thyroid (hyperthyroidism), may damage thyroid tissue.
- Medications: Certain drugs, such as lithium (used for bipolar disorder) and amiodarone (for heart rhythm problems), can impair thyroid function.
- Congenital Hypothyroidism: Some babies are born with an underdeveloped or malfunctioning thyroid gland. In Australia, newborn screening helps detect this early, allowing timely treatment.
- Iodine Deficiency: Globally, iodine deficiency is a leading cause of hypothyroidism. However, thanks to Australia’s iodised salt program introduced in 2009, iodine deficiency is now rare in the country.
- Genetic Disorders: Rare inherited conditions can affect thyroid hormone production or regulation.
- Pituitary or Hypothalamic Disorders: Though uncommon, damage or disease affecting these brain regions can reduce thyroid-stimulating hormone (TSH) production, leading to secondary hypothyroidism.
- Pregnancy and Postpartum Changes: Some women develop thyroid dysfunction during or after pregnancy, sometimes linked to autoimmune processes.
Who Is Most at Risk?
Hypothyroidism is more frequently diagnosed in women than men and is especially common in people over 60 years of age. Individuals with other autoimmune diseases, such as rheumatoid arthritis or type 1 diabetes, are also at higher risk.
Recognizing the Impact
When the thyroid gland fails to produce sufficient hormones, the body’s metabolism slows down, causing symptoms like fatigue, weight gain, cold sensitivity, dry skin, constipation, depression, and memory difficulties. In some cases, the thyroid gland may enlarge, forming a visible lump known as a goitre.
Importance of Early Detection and Management
Because hypothyroidism develops gradually and symptoms can be subtle, it often goes unnoticed until the condition is advanced. Blood tests measuring TSH and thyroid hormone levels are essential for diagnosis. Once identified, hypothyroidism is typically managed with daily thyroid hormone replacement therapy, which effectively restores hormone balance.
In summary, hypothyroidism in Australia is mainly caused by autoimmune thyroiditis (Hashimoto’s disease), with other contributors including surgery, radiation, medications, and rare genetic or pituitary disorders. Thanks to public health measures like iodised salt, iodine deficiency is now uncommon. Awareness of these causes helps Australians seek timely medical advice and maintain thyroid health.