The thyroid gland is a vital endocrine (hormone) secreting gland which plays a major role in the metabolism, growth and development of the human body. Principally it secretes two iodine based thyroid hormones (T3 and T4) which regulate many body functions including body temperature, heart rate and blood pressure by constantly releasing a steady flow of thyroid hormones into the bloodstream. If the body needs more energy, hormone release is increased, and if less energy is needed, release slows down. Consequently, overactivity and underactivity of the gland are associated with symptoms related to metabolism.
Calcitonin is the third hormone secreted by the gland. This is involved in calcium and bone metabolism.
The thyroid gland is a found in the front of the neck, just under the voice box. It has two lobes which are joined and from the front has the shape of a butterfly. The lobes lie alongside the trachea (windpipe).
Thyroid enlargement (Goitre)
Sometimes solid or fluid-filled nodules (lumps) form within the thyroid gland most of which aren’t serious and don’t cause symptoms. However a small percentage of these nodules are cancerous, so it is important to consult your doctor if you feel that your thyroid has enlarged.
Most people don’t know they have a thyroid nodule until their doctor discovers it during a routine medical exam or following a scan done for another health reason. Some thyroid nodules can become large enough to be visible or make it difficult to swallow or breathe.
Thyroid nodules are more common women and in patients over the age of 50.
Most thyroid nodules don’t cause signs or symptoms but if they become large that they can:
- Be felt
- Be seen, as a swelling at the base of the neck
- Press on the trachea (windpipe) or oesophagus, causing shortness of breath or difficulty swallowing
Sometimes thyroid nodules produce extra thyroid hormones which cause symptoms (hyperthyroidism), which can present with one or more of the flowing symptoms:-
- Prominent / bulging eyes
- Increased metabolic rate with irritability, restlessness, and weight loss
- Irregular / rapid heart rate with increased blood pressure
- Shaking hands and sweating
- Increased bowel movement
- Brittle hair and hair loss
- Irregular menstrual cycles and breast development (in men)
Conversely thyroid nodules can also produce reduced levels of thyroid hormones and the patient develops symptoms of hypothyroidism, which include one or more of the following symptoms:-
- Fatigue and memory problems
- Weight gain and sensitivity to cold
- Muscle weakness, aches, tenderness, and stiffness
- Joint pain, stiffness and swelling
- Dry skin, puffy face, dry hair, and hair loss
- Raised blood cholesterol
- Irregular menstrual periods (or cessation of menstruation)
In children hypothyroidism can lead to
- Delayed / poor growth
- Delayed puberty
- Poor mental development
Most thyroid nodules are caused by benign conditions. The most common causes for thyroid enlargement are :-
- Adenoma. An overgrowth of normal thyroid tissue. Some thyroid adenomas lead to hyperthyroidism.
- Thyroid cyst. A fluid-filled cavity within the thyroid tissue (which can sometimes have solid components within it). Whilst cysts are usually non-cancerous, the solid components can sometimes contain cancerous cells.
- Hashimoto’s Disease. A thyroid disorder causing inflammation of the gland which can create nodules. Hashimoto’s often leads to hypothyroidism.
- Multinodular goitre. A benign condition in which multiple distinct nodules (and sometimes cysts) develop within the gland. Its cause is not clear however sometimes one nodule becomes dominant.
- Thyroid cancer. Account for less than 5% of all thyroid nodules however a nodule that is large and hard or causes pain or discomfort is more worrisome and should be checked by a doctor. Thyroid cancers normally start as vey small nodules which grow over time.
Having a family history of thyroid cancer, other endocrine tumours or having radiation exposure (from medical therapy or from nuclear fallout) can increase your risk of developing the disease.
- Iodine deficiency goitre. Lack of dietary iodine can nodular or difuse enlargement of the thyroid gland. Iodine deficiency is uncommon in the western world (where iodine is routinely added to table salt and other foods) but can be found in areas of the world where iodine supplementation is not routinely available.
When assessing a lump or nodule in the neck, the doctor’s main objective is to rule out the possibility of cancer and will undertake one or more of the following tests:
- Physical exam is necessary to feel the gland and to assess patients for signs and symptoms of hyperthyroidism or hypothyroidism. .
- Thyroid function tests measure blood levels of thyroid-stimulating hormone (TSH) and the T3 & T4 hormones produced by your thyroid.
- Ultrasound is an imaging technique using sound waves to produce images which provide excellent information about the shape and structure of the gland and nodules. It easily distinguishes cysts from solid nodules and is used as a guide whilst performing fine-needle aspiration biopsy.
- Fine-needle aspiration biopsy is a procedure which involves the placement of a thin needle, under ultrasound guidance, into a nodule to removes a sample of cells which are analysed in the laboratory to exclude cancer.
- Isotope thyroid scans use safe doses of radioactive iodine to assess the function of thyroid nodules. Nodules which produce excess thyroid hormone (hot) take up more of the isotope than normal thyroid tissue does and are almost always noncancerous. Cold nodules take up less of the isotope and can be cancerous. An isotope thyroid scan can’t distinguish between cancerous and non-cancerous nodules. At the Specialist Medical Clinic we recommend removal of all solid cold nodules.
The treatment of thyroid nodules depends entirely on the clinical diagnosis and the results of tests. Our team will discuss the various treatment options available and explain the risks associated with each therapy.
Treatment options include
- Watchful waiting
- Thyroid hormone therapy
- Radioactive iodine
- Anti-thyroid medications
- Alcohol ablation