The thyroid gland is a butterfly-shaped endocrine gland located in the front of the lower neck just below the Adam’s apple. The thyroid gland consists of left and right thyroid lobes connected by a bridge of thyroid tissue known as the thyroid isthmus. The thyroid gland produces a hormone called thyroxine which helps regulates the body’s normal metabolic processes.
What disorders can occur?
Disorders of the thyroid gland are common. These include nodules, goitre, cancer and functional disorders of the thyroid due to excessive or insufficient thyroid hormone production (hyper- or hypothyroidism).
Thyroid nodules are common and may be present in up to 20-50% of adults. Any new thyroid nodule or recent change of a known thyroid nodule requires evaluation to exclude the possibility of an underlying malignancy. The diagnostic work up of a thyroid nodule usually includes a thorough clinical history and examination, blood tests for thyroid function, ultrasound imaging of the thyroid and associated lymph nodes, and a fine needle biopsy. Small lesions with a low risk of malignancy may not require biopsy in the absence of any suspicious features or risk factors for malignancy and can be monitored by repeat ultrasound imaging.
A “goitre” refers to any enlargement of the thyroid gland. The most common cause of a goitre is due to the presence of multiple thyroid nodules (multinodular goitre). The underlying cause of multinodular goitre at a molecular or genetic level is still unclear however the development of a goitre is more common in women, in those with a familial history and in regions with an iodine or selenium deficiency. New Zealand soils are iodine and selenium deplete. As a result multinodular thyroid disease is common in New Zealand. Progressive enlargement of thyroid goitre may result in compressive or obstructive symptoms which can result in difficulty with breathing, swallowing or obstruction to venous blood flow.
Thyroid cancers in the early stage produce no symptoms. As the cancer grows a lump or nodule can be felt in the neck. In some cases the first sign of thyroid cancer will be enlargement of associated lymph nodes in the neck or after more distant spread of disease (most commonly to bone).
Features that should raise the suspicion of a cancer include:
- A painless thyroid mass enlarging rapidly over a period of a few weeks
- Enlarged cervical (neck) lymph nodes
- Unexplained hoarseness or stridor associated with a thyroid mass
- Insidious or persistent pain lasting for several weeks
- A family history of thyroid cancer
- History of previous irradiation or exposure to high environmental radiation
- A child with a thyroid nodule
There are different types of thyroid cancer with the most common types (papillary and follicular thyroid carcinoma) highly curable if detected and treated early. In younger patients up to 97% of these types of thyroid cancer may have a long-term cure or control of disease with appropriate treatment. Treatment of thyroid cancer involves surgical excision of the thyroid and any involved lymph nodes and in most cases is followed by treatment with radioactive iodine.
Less common thyroid cancer types include medullary, Hurthle cell, insular and anaplastic carcinoma. These thyroid cancer types generally do not respond well to medical treatment and have a less favourable prognosis.
Thyrotoxicosis / Grave’s Disease
Thyrotoxicosis is caused by excess thyroid hormone. The cause of thyrotoxicosis may be due to excess iodine ingestion, inflammation of the thyroid (thyroiditis), a solitary toxic nodule, a toxic multinodular goitre or due to Graves’ disease. Functional disorders of the thyroid gland are best investigated and managed by an endocrinologist who will determine the most likely cause and most appropriate course of action for treatment. Initial treatment will usually consist of medical control of thyrotoxicosis with the anti-thyroid drug Carbimazole or Propothyrouracil. Either of these drugs can have significant side-effects and have potential mutagenic effects on a developing embryo therefore should be used with caution particularly in pregnancy. In most cases once it is determined the thyrotoxicosis is unlikely to resolve definitive treatment of the thyrotoxicosis will be recommended by the Endocrinologist.
Definitive treatment options for thyrotoxicosis are:
- ablation of the thyroid with radioactive iodine
- surgical excision of the thyroid (thyroidectomy).
Radioactive iodine is taken by mouth and finds it’s way to the thyroid after absorption by the intestinal tract via the blood stream. It is absorbed and highly concentrated in the thyroid gland resulting in a radiation injury to the thyroid gland and eventual death of thyroid tissue. The effect on the thyroid gland is not immediate and ablation occurs over a period of approximately three months. The radioactive iodine is excreted via urine, sweat and faeces over a period of one to two weeks. During this period of time patients are recommended to avoid close contact with family members (particularly children) and to avoid contact with the general public in order to limit unnecessary radiation exposure to other individuals. Women of child-bearing age are recommended to avoid pregnancy for one year after treatment. Approximately 40% of patients will require a second dose of radioactive iodine for an adequate response.
Surgery for a solitary toxic nodule consists of a hemithyroidectomy (thyroid lobectomy) under general anaesthetic. Where appropriate some patients may be able to be discharged on the same day of surgery. Where there is a more diffuse involvement of the thyroid such as in a toxic multinodular goitre or in Graves’ disease a total (or near-total) thyroidectomy is required. Surgery is considered a “quick fix” option for thyrotoxicosis with rapid normalisation of thyroid function after surgery. Almost all patients are discharged the following day of surgery on simple analgesia and have usually returned to work by one to two weeks after surgery. Thyroidectomy for this condition should be performed by an experienced thyroid surgeon to minimize the risk of post-surgical complication. I have a large volume of surgical experience with thyrotoxicosis including Graves’ disease and recently published a peer reviewed journal article on this topic.
Whether a patient chooses radioactive iodine or surgery for treatment of their thyrotoxicosis should depend on the guidance given by their endocrinologist as well as the patient’s own preference after being adequately informed of the treatment options. Whilst radioactive iodine treatment is considered a safe treatment for thyrotoxicosis recent literature does suggest a small associated increased risk of malignancy in those treated with radioiodine. The potential increased risk of malignancy however should be weighed up against against the approximately 1% risk of complications associated with thyroid surgery. Most patients referred to me for thyroidectomy for this condition have a personal preference to avoid treatment with radiation and the isolation required during the washout phase of radioactive iodine and accept the small risk of complication with surgery.
In most cases a patient can choose their preferred mode of treatment however in some situations one treatment option may be more appropriate than the other. Treatment for thyrotoxicosis should be individualized depending on the patient’s needs and preference. Generally the recommendations I make to my patients are as follows:
Indications for surgery:
- Any patient with poor medical control of thyrotoxicosis or need for cessation of antithyroid medications making a “quick fix” solution necessary.
- Any patient with Grave’s disease and associated eye involvement (Graves’ ophthalmopathy) as radioiodine may exacerbate the severity of eye symptoms
- Previous adverse reaction or allergy to iodine
- Young patients
- Any women of child bearing age
- Social situation making isolation from other family members difficult
- Personal preference for avoidance of radiation
Indications for radioiodine:
- In the elderly or a patients with other significant medical issues making an anaesthetic or surgery unsafe
- A career dependent on voice (eg. professional singers) as subtle voice change can occur after surgery even without laryngeal nerve injury
- Preference for avoidance of surgery when radioiodine is not contraindicated
Why do I need thyroid Surgery?
Thyroid surgery may be required for the following reasons:
- Symptomatic thyroid nodule(s)
- Toxic (over-active) solitary nodule
- Toxic (over-active) multinodular goitre
- Graves’ disease
- Compressive or obstructing goitre
- Diagnostic procedure (suspicion of malignancy)
- Treatment of thyroid cancer
The operation requires a general anaesthetic and a stay in hospital, which is normally just overnight. Depending on the condition and the operation performed some of my patients may be able to be discharged on the same day of surgery.
The most common thyroid operations are either a partial thyroid resection (hemithyroidectomy or thyroid lobectomy) or a total thyroidectomy.
- A hemithyroidectomy (or thyroid lobectomy) involves removal of one of the thyroid lobes leaving the remaining half of the thyroid gland undisturbed. The most common reason for a hemithyroidectomy is the removal of a thyroid nodule for diagnostic purpose, removal of a symptomatic thyroid nodule or for the treatment of a goitre affecting only one lobe of the thyroid gland. In most patients the remaining thyroid gland is able to compensate for the loss of one half of the thyroid and will produce enough thyroid hormone to avoid the need for thyroid hormone replacement.
- A total thyroidectomy involves the removal of all visible thyroid tissue. The most common reasons for total thyroidectomy are for treatment of a symptomatic multinodular goitre, surgical treatment for excess thyroid hormone production or thyroid cancer. Surgical treatment for thyroid cancer may also require removal of lymph nodes in the neck (neck dissection)
What incision will I have?
Access to the thyroid gland requires an incision in the neck. The incision is placed in the midline over the lower part of the neck utilising a natural skin crease where possible. The skin is closed with a single absorbable and buried suture. Most thyroidectomy incisions heal to produce an excellent cosmetic result. In appropriate cases I perform a minimally invasive / minimal access thyroidectomy procedure which can be performed through an incision as small as 2.5cm.
For wound closure I use dissolving sutures and rarely require wound drains. This optimizes the cosmetic result and minimizes the discomfort a patient may experience with surgical drains or skin staples.
What will the scar look like?
The size of incision is kept to a minimum and can be as small as 2.5cm for minimal access thyroidectomy cases. For a typical thyroid case the incision size will usually range from between 4 - 8cm depending on the patients body type, procedure and size of the thyroid gland. In the early phase of healing the scar may be raised and red for several months but with maturation of the scar will fade to a thin white line. Patients with darker skin may initially have exaggerated pigmentation of the scar but this will also fade with time. Very rarely some patients develop a thick exaggerated scar (hypertrophy or keloid scar) but this is uncommon.
What complications can occur?
Most thyroid operations are straightforward and associated with few problems. As an expert thyroid and parathyroid surgeon my overall long term complication rate for thyroid and parathyroid surgery is less than 1%. However all operations carry risks which include the potential for postoperative infections, bleeding into the wound and miscellaneous problems due to anaesthesia. Specific complications related to thyroid surgery are rare but include injury to the laryngeal nerves (which may result in a hoarse voice) and hypocalcaemia (low calcium levels) due to inadequate parathyroid gland function. All patients who have had a total (or near total) thyroidectomy will require long term thyroid hormone replacement as the patient can no longer produce thyroid hormone without a thyroid gland.
A specific problem related to thyroid surgery is injury to one or both recurrent laryngeal nerves. These nerves pass very close to the thyroid gland and control movement of the vocal cords. Injury to these nerves may result in significant hoarseness and weakness of the voice. The external laryngeal nerve may also be injured and this results in a weakness of the voice although the sound of the voice is largely unchanged. Difficulty may be found with the high notes when singing, the voice may tire more easily and the power of a shout is reduced. Careful surgery and routine identification of the laryngeal nerves reduces the risk of permanent accidental damage to a very low level (<1%) but cannot absolutely eliminate it. An injury to the laryngeal nerves is diagnosed by laryngoscopy whereby a fibreoptic camera is used to view and assess vocal cord function. An injury to both nerves is extremely rare but is a serious problem and may require a tracheostomy.
Subtle voice change may occur in up to 30% of patients even if no injury to the laryngeal nerves has occurred. This is most likely due to the unavoidable scarring that occurs around the larynx and windpipe after thyroidectomy but can be minimised by careful surgical technique and minimal tissue injury. The subtle change of voice is often not detectable to the casual observer and usually does not impair the patient’s day to day activities. In most cases any change of voice will improve with time as the scar tissue matures and softens.
Low blood calcium levels
Four tiny glands adjacent to the thyroid gland are known as parathyroid glands. The normal parathyroid gland is only several millimetres in size however these glands play a crucial role in the maintenance of calcium levels in body fluids. Patients undergoing surgery to the thyroid gland are at risk of developing a low calcium levels if the parathyroid glands stop working after surgery. This may occur if inadvertent removal of the parathyroid glands has occurred or if the blood supply to the parathyroid glands has been compromised. The risk of this complication is minimised by meticulous surgical technique and by re-implanting any compromised parathyroid glands into nearby muscle tissue to allow the gland the regrow and develop a new blood supply. Unfortunately even when the parathyroid glands have been found and appear to be adequately preserved they may not function after surgery in a small number of patients. In most cases this will be temporary and the parathyroid glands will recover however may be permanent in approximately 1% of patients after thyroidectomy. Low calcium levels will result in a sensation of “pins and needles” in the fingers, around the mouth or face and often also muscle cramps. If this occurs the patient will then need to take calcium and/or vitamin D tablets on a permanent basis.
The risk of bleeding after thyroid surgery is low at approximately 1%. Any significant bleed will usually present within the first few hours after surgery and may require a second brief operation to evacuate the blood clot and identify any bleeding point. With appropriate and timely management of this complication post-operative recovery, time in hospital and further complication risk is usually not affected.
Will I need to be on Medications after my thyroid surgery?
If it has been decided to remove all of the thyroid gland the patient will require lifelong replacement of thyroid hormone. Fortunately this is a straightforward once daily regimen with little requirement for adjusting the dosage. In most cases I recommend a short course (2-3 weeks) of calcium +/- Vitamin D supplementation after surgery to avoid a temporary drop of calcium levels should the parathyroid gland function require time for recovery.
In the case of a partial thyroid resection (thyroid lobectomy or hemithyroidectomy) the remaining gland is usually able to produce sufficient hormone to compensate. This is determined by a post-operative blood test for thyroid function. Insufficient thyroid hormone production does occasionally occur but is usually associated with a pre-existing thyroid condition.
How long will I be in hospital and expected recovery time?
Almost all of my patients are comfortable on simple analgesia and able to be discharged after just one overnight stay. Depending on the condition and the operation performed some of my patients may be able to be discharged on the same day of surgery.
As a general rule I advise one week of recovery prior to returning to driving so that any early post-operative discomfort or neck stiffness does not impair driving ability.
Most of my patients are able to return to work within 1-2 weeks after surgery for sedentary or light duty occupations and within 4-6 weeks for work requiring heavy manual labour.