Thyroidectomy (Surgery to remove Thyroid Gland)

Thyroidectomy is the medical term for the surgical procedure to remove the thyroid gland. The indications for thyroidectomy are:
- thyroid cancer
- thyrotoxicosis (symptoms of excess of thyroid hormones; refer to earlier topic)
- huge goitre with compressive symptoms (eg. difficulty breathing, difficulty in swallowing)
- cosmesis & patient's request (unsightly neck swelling)

The surgery is performed under general anaesthesia and hospital admission is necessary. Prior to surgery, the patient's thyroid function should be assessed. Patients who are hyperthyroid should be treated with anti-thyroid medications (carbimazole or propylthiouracil) to reduce the levels of thyroid hormones. This is because patients who are hyperthyroid will have an increased risk of a 'thyroid storm'. A thyroid storm is an uncommon but serious complication of thyroid surgery which is precipitated by an acute exacerbation of thyrotoxicosis.

The patient should also undergo an indirect laryngoscopy to assess the patient's vocal cords for any abnormalities. This is because the nerves supplying the vocal cords (recurrent laryngeal nerve) are situated just adjacent to the thyroid gland and any injury will affect the vocal cords. If the goitre is suspicious for cancer, a fine needle aspiration cytology (FNAC) should be carried before surgery to confirm the diagnosis of a cancer. For huge goitres, a chest x-ray or a CT-scan should be done to check for any extension of the thyroid gland inferiorly under the sternum. This would make the surgery more extensive and longer.

After all the pre-operative assesment is done, the patient is admitted for anaesthetic assessment and surgery. During surgery an incision is made just above the collar bones. It is usually around 5-8cm in length depending on the size of the goitre.
There are two options for surgery for thyroid swellings. A hemi-thyroidectomy is performed if the patient has only a single thyroid nodule on one side or small early thyroid cancers (<1cm)>. A total thyroidectomy is performed in patients with a multi-nodular goitre involving both thyroid lobes, thyroid cancers, Graves' disease & thyrotoxicosis. Duration of surgery for a total thyroidectomy ranges from between 1-4 hours depending on the extent of disease and the size of the thyroid gland. Sometimes it might take longer if lymph node dissection is required in cancer patients.

The complications of thyroidectomy can be divided into early and late complications.

Early complications include:
- bleeding from the surgery wound
- voice change (due to swelling of the nerves)
- temporary low calcium levels (due to reduced function of parathyroid glands)
- wound infection

Late complications include:
- unsightly scar
- permanent low calcium levels (because the parathyroid glands were injured or removed during the surgery)
- permanent hoarseness of voice (injury to recurrent laryngeal nerve)
- vocal cord paralysis with difficulty breathing (injury to both recurrent laryngeal nerves)
- inability to produce a high pitched voice (injury to external branch of superior laryngeal nerve)
- permanent hypothyroidism (in total thyroidectomy, the body cannot produce any more thyroid hormones)

The parathyroid glands are located just behind the thyroid gland in the neck. Usually there are between 2 -6 parathyroid glands in everybody. Its main function is to maintain a normal level of calcium in our body. Due to its location near the thyroid gland, it has a risk of being injured or removed. However, the risk is approximately 1% only. Patients with permanent low calcium levels are treated with calcium supplement tablets.

The recurrent laryngeal nerve supplies our vocal cords. The nerve is located beside the thyroid gland on both sides. The risk of injury is approximately 1%. Injury to the nerve will cause hoarseness of voice (one sided injury) or breathing difficulty (both sided injury). Most patients will have a temporary hoarseness of voice due to swelling of the nerve during manipulation. This resolves spontaneously usually within 1 month.

The external branch of superior laryngeal nerve are located near the upper lobes of the thyroid gland on both sides. Injury to the nerve will lead to an inability to produce high-pitched voice.

Patients who have had a total thyroidectomy will need thyroid hormone supplements for life. This is because there is no more thyroid gland to produce thyroid hormones. This is usually prescribed in the form on levo-thyroxine (L-thyroxine) tablets.

Hyperthyroidism

Hyperthyroidism means an increase in the amount of circulating thyroid hormones (T3 & T4) in the body. This condition leads to thyrotoxicosis which represents the symptoms and signs which occurs due to increased thyroid hormones.
Hyperthyroidism can occur due to an autoimmune disease such as Graves' disease, a toxic hyperfunctioning goitre or solitary nodule, due to medications such as lithium, secondary to pituitary tumours in the brain, due to an inflammatory process (thyroiditis), ectopic thyroid tissue or rarely due to thyoid cancers.
The common symptoms of thyrotoxicosis are: sweating, palpitations, irritability, heat intolerance, weight loss, increased appetite, increased bowel movements, impaired fertility, reduced libido, hyperactivity and insomnia. Signs associated with thyrotoxicosis are an irregular, rapid pulse, tremor, warm moist skin, muscle weakness, enlargement of the male breast tissue and goitre.
Diagnosis of hyperthyroidism is made in the presence of the symptoms and signs of thyrotoxicosis with a confirmatory blood investigation for raised levels of serum T3 and T4. Then, the cause for the hyperthyroidism should be investigated. Usually an ultrasound of the neck is done to assess the goitre.
Patients with Graves' disease will also have specific signs for the disease such as protruded eyeballs (proptosis), swelling around the eyes (periorbital oedema), limited eyeball movement (extraocular muscle involvement), deterioration of vision and swelling of the lower limb skin (pretibial myxoedema). Blood investigations for anti-thyroid peroxidase and anti-thyroglobulin antibodies are diagnostic.
Treatment of hyperthyroidism is aimed at reducing the levels of thyroid hormones and also reducing the sympathetic activity for control of symptoms. Two drugs commonly used to reduce thyroid hormones are propylthiouracyl and carbimazole. Both these drugs reduce the production of thyroid hormones in the body. Propanolol, a beta-blocker commonly used in hypertension, is used for symptomatic control in patients with thyrotoxicosis.
Radioactive iodine ablation of the thyroid gland can also be used as a first line treatment of thyrotoxicosis. Thyroid follicular cells are destroyed by the radiation emitted. However, this is contraindicated in patients who are pregnant, breastfeeding, who plan to get pregnant within 6 months or who are in contact with children.
Surgery (thyroidectomy) is indicated in patients with large goitres, patients who are contraindicated for radioiodine ablation and patients who wish to have their thyroids removed. This is considered as the definitive treatment for thyrotoxicosis. Patients will have to be started on anti-thyroid medications prior to surgery to reduce the risk a thyroid storm which can be deadly. The risks and complications of thyroid surgery will be discussed in the next article.

The Thyroid Gland

The thyroid gland is an endocrine (hormone secreting) gland which is anatomically located in our necks. It consists of two lobes (left and right) which is connected by an isthmus. It has a rich blood supply and consists of thyroid cells which secrete triiodothyronine (T3) and also thyroxine (T4). These hormones help regulate the metabolic rate of our bodies. Too high or too low levels of T3 or T4 will lead to symptoms of hyper or hypothyroidism.
Lying within close proximity to the thyroid gland on each side are the superior laryngeal nerves, the recurrent laryngeal nerves and the parathyroid glands. The superior laryngeal nerves helps maintain a high pitch voice and the more important recurrent laryngeal nerve is the principle nerve supply to our vocal cords. Any injury or damage to this nerve will cause hoarseness of voice and difficulty in breathing. The parathyroid glands are important for calcium regulation in our body.Common problems associated with the thyroid gland are generalised swelling of the gland (goitre), solitary nodule within the gland, hyperthyroidism or hypothyroidism and thyroid cancers.
Goitres can occur due to iodine deficiency, physiological changes associated with pregnancy and puberty, due to thyroid hormonal imbalance or as part of an inflammatory process. Solitary nodules are usually benign or malignant tumours of the thyroid cells. Hyperthyroidism occurs due to an increase in levels of T3 and T4 in our bodies and hypothyroidism occurs due to low levels of thyroid hormones.
Thyroid cancers are more common in women and are divided into a few types according to the type of cells which turn malignant. Approximately 10% of all thyroid nodules are cancers.
We will discuss further on the diseases affecting the thyroid gland in the next article.