Thyroid Thoughts By Dr David Moore
Situated at the base of the neck (almost exactly where a bow tie is worn!), the Thyroid Gland participates in an extraordinary array of bodily processes. At the command of Thyroid Stimulating Hormone (‘TSH’ – released by the Pituitary Gland of the Brain) the Thyroid produces two major hormones: Tetra- and Tri-iodothyronine (T3 and T4). As suggested by their names, these hormones are assembled from Iodine and they act on virtually every body tissue, exerting their effects primarily by regulating the expression of gene products within cells. This broad and profound physiological role means Thyroid hormones are crucial for normal brain and organ development during pregnancy and they play a central part in the co -ordination of metabolism throughout adult life[1].
The manifestations of Thyroid disorders are therefore bafflingly wide-ranging (fatigue, weight gain, hair loss, depression, anxiety, disturbances to bowel function and menstruation) but they can generally be grouped into consequences of thyroid over-activity (hyperthyroidism) and under-activity (hypothyroidism). A crude but effective analogy for this axis of metabolic control by thyroid function involves thinking of a car’s accelerator and brakes – thyroid over-activity ‘over-drives’ human physiology, producing such symptoms as a racing pulse, tremulousness and loose stool. Conversely, thyroid under-activity slows bodily processes to a crawl – resulting in the symptoms of fatigue, weight gain and depression for which Thyroid tests are commonly sought.
Whilst hypothyroidism is relatively common (perhaps 5 in 1000 Australians will suffer it)[2], the generality of symptoms associated with the condition (and its various causes) results in frequent ordering of thyroid tests. In fact, thyroid pathology orders have increased by more than 50% over the past 10 years despite the incidence of non-malignant thyroid diseases remaining relatively stable[3]. In General Practice differing beliefs have been expressed regarding the investigation and treatment of possible Thyroid disorders (especially amongst practitioners of Integrative Medicine) and this has prompted the Endocrine Society of Australia to make specific recommendations as part of the nationwide Choosing Wisely campaign[4]
Despite the difficulty involved in differentiation of thyroid disease there is one symptom which stands out: a lump in the neck. The term ‘goitre’ refers to enlargements of the thyroid gland that can be seen or felt and causes of a goitre range from insignificant benign nodules to thyroid cancer. The incidence of thyroid cancer in Australia (especially on the east coast) has increased by Five-fold in the last 30 years. It is uncertain whether this reflects a true escalation of disease or just diagnostic zeal, but thankfully the mortality attributable to thyroid cancer remains quite low[5]. As most thyroid lumps are discovered by patients or their family, the American Association of Clinical Endocrinologists has published self-examination instructions which can be found at http://www.thyroidawareness.com/neck-check.
We hope the information in this article is helpful, and if you have any questions or concerns regarding the health of your Thyroid gland please consult your GP.
[1] The Merck Manual of Diagnosis and Therapy (Merck, 1899).
[2] The Royal Australian College of General Practitioners, “RACGP – Hypothyroidism – Investigation and Management,” accessed April 16, 2016, http://www.racgp.org.au/afp/2012/august/hypothyroidism/
[3] The Royal Australian College of General Practitioners, “RACGP – Orders for Thyroid Function Tests – Changes over 10 Years,” accessed April 16, 2016, http://www.racgp.org.au/afp/2012/august/orders-for-thyroid-function-tests/.
[4] Choosing Wisely Australia, “Endocrinology Tests & Treatments: 5 Recommendations from Endocrine Society of Australia (ESA),” Choosing Wisely Australia, accessed April 16, 2016, http://www.choosingwisely.org.au/recommendations/esa.
[5] Emily J. Mackenzie and Robin H. Mortimer, “6: Thyroid Nodules and Thyroid Cancer,”Medical Journal of Australia 180, no. 5 (2004), https://www.mja.com.au/journal/2004/180/5/6-thyroid-nodules-and-thyroid-cancer.