Thyroid and Parathyroid Surgery
Thyroid Surgery
What and where is the Thyroid Gland?
The thyroid gland is an endocrine organ in the midline of the neck, just below the Adam's apple.
It consists of a right and left lobe joined across the front of the windpipe by a strip of thyroid
tissue, the isthmus.
The function of the thyroid is to convert iodine taken in the diet, into thyroid hormone (thyroxine).
To avoid iodine deficiency in New Zealand soil it is put into table salt. Another major source of
dietary iodine is seafood.
Diseases of the Thyroid gland are common and can occur when the thyroid produces too much or too
little thyroid hormone. In addition, sometimes the thyroid becomes enlarged or develops tumours,
which may be benign (non-cancerous) or malignant (cancerous).
Many thyroid p roblems can be treated with medication, but sometimes surgical removal of
either part or the entire thyroid is required.
Thyroxine has a major regulatory role for metabolic rate. An overactive thyroid with
elevated levels of thyroid hormone in the blood is called Hyperthyroidism. The
commonest cause of this condition is an immunological disease call “Graves Disease”.
The symptoms of hyperthyroidism include tremor, heat intolerance, irritability, increased energy,
weight loss and frequently, bulging eyes. The bulging eyes coupled with elevated levels of thyroid
hormone are virtually diagnostic of Graves Disease.
Treatment of Hyperthyroidism usually involves stabilising the patient with drugs to block the release
of thyroid hormone from the thyroid, plus the use of beta-blocking drugs to slow the heart rate.
Subsequently definitive management of hyperthyroidism usually involves thyroid ablation with a drink
of radio-active iodine (I131) which destroys many of the overactive cells in the gland. However,
occasionally thyroidectomy may be a preferred option. Surgery rather than radio-iodine may be
indicated to manage hyperthyroidism in children, pregnant or lactating women, as a result of patient
preference, or if the hyperthyroidism is due to exposure to the cardiac medication amioderone.
A deficiency of thyroxine from an under-active gland results in a low metabolic rate
condition called hypothyroidism. This condition results in tiredness, weight gain,
lethargy, and slowness of speech and thinking. The commonest cause of hypothyroidism is an immunological
disorder namely Hashimotos Thyroiditis. Hashimoto's Thyroiditis is a type of autoimmune thyroid
disease in which the immune system attacks and destroys the thyroid gland resulting in low levels
of thyroid hormone in the blood. Treatment is simple with the use of daily thyroxine medication.
Both Hyper- and Hypo-thyroidism are diagnosed by measuring the thyroid hormone levels i
n the blood (T4 and TSH, and occasionally T3).
Thyroid Lumps
- Goitre
When the thyroid gland grows excessively a swelling called a Goitre forms around
the front of the throat. The entire gland may be involved or a single side. Patients with overactive
or under-active thyroid glands may also have goiter but most patients with goiters have normal thyroid
function. In patients with goiter there is a metabolic defect involving the production of thyroxine and
this defect is often familial.
Small goiters often do not require treatment but large goiters can cause pressure on the windpipe and
gullet. This can result in difficulty swallowing, shortness of breath, chronic dry cough and a sensation
of increased pressure in the neck.
Surgery to remove the thyroid gland is usually necessary to treat large goiters that are causing symptoms.
Surgery is also necessary if there is suspicion of thyroid cancer in one of the enlarged thyroid lumps.
(See FNA Below).
For large goiters a CT scan is often useful to asses the extent of compression (squashing) of the trachea
(windpipe) and also assess the extent of extension of the goiter into the chest. See CT scans in Figs b
elow:
2 Solitary Nodule
A solitary thyroid lump is a common clinical problem. Over 90% of solitary nodules
are benign.
The 5-10% of thyroid nodules that are not benign, are usually low-grade cancers which
are usually curable. (See FNA & Thyroid cancer below). A solitary thyroid is present in the Fig
below.
3 Cysts
A cyst is a collection of fluid. Thyroid cysts are common. They can be diagnosed by
ultrasound or by needle aspiration. Sometimes draining the cyst makes the cyst disappear. If
multiple aspirations are required, resection of the thyroid lobe may be required to exclude a cystic
thyroid cancer.
4 Colloid Nodules
These are benign nodules made up of thyroid tissue. They can be single or multiple
and can become large. They can generally be diagnosed on fine needle biopsy and surgery is
usually not required.
5 Benign Thyroid Tumours (Adenomas)
Although these tumours are benign they often require surgery as differentiating between
benign tumours and cancers based on pre-operative fine needle aspiration (FNA) of a thyroid lump and
subsequent cytology (looking at the aspirate under the microscope) is not always reliable. As a consequence,
surgery is often recommended for diagnosis. This is especially true if the aspirate is reported as: “
atypical”, or as a “follicular neoplasm”. When there is doubt as to the nature of a thyroid
lump the patient requires an operation under general anaesthesia. The lobe of the thyroid that has the nodule
in it is removed and while the patient is asleep the nodule is frozen and looked at under the microscope (Frozen
Section). If the so-called benign lesion is actually a papillary cancer (see below) this can often be diagnosed
by frozen section. The other types of thyroid cancer aside from papillary cancer cannot however be reliably
diagnosed at frozen section, and if these turn out to be malignant on final pathological assessment (paraffin
section pathology), despite the frozen section appearing to be benign (false negative frozen section) a second
operation is often required, usually 1-2 weeks after the initial surgery.
Thyroid Cancer
The common thyroid cancers are the differentiated cancers:
| Papillary cancer: |
70% of total |
| Follicular cancer: | 20% of total |
| Hurthle Cell cancer (a sub-group of follicular cancer): | 5% of total |
| Medullary Cancer | 5% of total |
Papillary cancers have a tendency to spread to neck lymph glands while follicular cancers tend
to spread by blood to bone and lungs. The prognostic factors for differentiated thyroid cancers are: Age of
the patient (young patients do better), the size of the cancer (lumps >4 cm do worse than smaller lumps)
and how readily the cancer can be resected with a clear margin of normal tissue. If lymph glands are involved,
they are usually removed by performing a neck lymph node dissection (see Neck dissection of website)
In addition, outcomes for thyroid cancer are often improved by employing one or more drinks
of adjuvant radio-iodine (I131) to destroy any residual thyroid cancer cells after surgery. This drink has a
very few complications.
Medullary cancer is one of the least common types of thyroid cancer. Some types of medullary
cancer are familial and as a result may occur in early childhood. Familial medullary thyroid cancers may be
associated with the presence of other endocrine tumours involving the adrenal glands, pituitary gland,or
other sites. Outcome for medullary cancer depends whether it is the sporadic type or the familial type as
well as how early it is detected, how big the primary lesion is, whether lymph nodes are involved, and how
high the plasma calcitonin level is. The hallmark of medullary cancer is the production of increased levels
of the hormone calcitonin. This hormone is produced by the “C cells or para-follicular cells of the
thyroid and is involved in the regulation of calcium metabolism.
Diagnosis of Thyroid Cancer
Physical examination is useful to gauge the size of the thyroid lump and
whether it feels benign or malignant, as well as whether there are palpable lymph nodes present.
Ultrasound (US) is useful to assess thyroid nodules and determine whether
they are solid or cystic. Ultrasound is also useful to assess whether lymph node involvement is present.
In addition US can be useful to guide an FNA biopsy to ensure the right aspect of a lump is the site of
the biopsy (US guided FNA biopsy)
Fine Needle Aspirate Cytology (FNA). This is the most important method for
evaluating thyroid lumps. A small sample of the thyroid is removed using a small (23 or 25 gauge) needle
and this is made into a slide and examined microscopically. The likely readings are:
- Benign follicular patterns – this is 95% accurate
- Papillary Cancer – this is 95% accurate
- Atypical pattern or follicular neoplasm – this indicates a 20% chance that
the lesion is malignant
Surgery is usually performed for options 2 and 3 while a “wait & watch”
approach is often used for option 1 whereby sequential ultrasounds are performed over many months
looking for interval change in the size of the lump.
Types of Thyroid Surgery (Thyroidectomy)
Surgery of the thyroid may be needed if it is:
- Over active
- Enlarged or nodular, resulting in a goiter
- Cancerous or suspected of being cancerous
Total Thyroidectomy
Total thyroidectomy (removal of both Right and Left thyroid lobes) is the preferred operation
for most thyroid conditions: most thyroid cancers, most goiters, and most over-active thyroids where
surgery is considered to be the preferred treatment rather than the more common treatment with radio-iodine.
Following total thyroidectomy, thyroxine tablets must be taken daily for life to replace the
thyroid hormone that the thyroid produces. In the short term calcium and/or vitamin D tablets may also be
required due to damage to the parathyroid glands which is common during total thyroidectomy but almost always
this injury to the parathyroids recovers and long term requirement for calcium replacement is rare.
Thyroid Lobectomy
When a nodule is suspicious for cancer on FNA, but not definitely malignant, removal of half of
the gland is often appropriate. In addition a frozen section may be performed while the patient is asleep in
order to get a clearer idea whether the suspicious lesion is benign or malignant thereby allowing the opposite
side of the thyroid to be removed if need be and preventing the patient having to undergo a second surgery on
another day. Frozen Section is a reliable method for diagnosing papillary cancer but is not reliable for
diagnosing follicular cancer or follicular variant of papillary cancer (see above under FNA and Frozen section).
Thyroxine is often not requires following removal of only half of the thyroid gland.
Technique of Thyroidectomy
Thyroid surgery is performed under general anaesthesia through an incision in or parallel to a
skin crease in the front of the neck. The central neck muscles are exposed and then retracted exposing the Left
and Right lobes of the thyroid.
The veins draining blood from the thyroid are tied off as are the arteries supplying blood to
the thyroid. The recurrent laryngeal nerves and the superior laryngeal nerves supplying the larynx (voice box)
are exposed and avoided. The para-thyroid glands which control blood calcium levels (4 in number: 2 on
each side) are preserved on their blood vessel if possible, and if this is not possible, they are transplanted
into a nearby muscle where they develop a new blood supply thereby remaining viable. Dissection of the thyroid
is performed close to the thyroid capsule specifically avoiding injury to the nerves and parathyroid glands.
See Fig below (RLN is recurrent laryngeal nerve):
Once the appropriate extent of surgery has been performed (1 or both sides of the thyroid), with
our without frozen section, the wound is closed after placing suction drain(s). These drains are removed usually
at 24-48 hours post surgery.
Frozen Section
This is when examination of tissue is performed under a microscope while the patient is asleep
to determine whether the tissue is malignant or not.
A pathologist comes to the operating suite to perform a frozen section, which usually takes
10-20 minutes. When the tissue examination is complete, the pathologist reports the result directly to the
surgeon in the operating room. Depending on the report either the other thyroid lobe is removed or the wound
closed. (also see above).
Neck Dissection for Thyroid Cancer
Both papillary cancer and Medullary cancer frequently spread to neck lymph glands. The
classification of neck nodes is shown in the two figures below. The lateral neck nodes are classified as
Levels 1-5, and the central neck nodes levels 6 and 7:
For thyroid cancers with a high risk of recurrence often a central neck dissection is performed at the
time of thyroidectomy. For patients who recur in the neck following thyroidectomy the 2 common levels for
recurrence to occur are levels 4 and 6. In this latter group of patients lymph glands are usually resected
from levels 2 to 6. Level 1 is only rarely involved with thyroid cancer.
Radio-Iodine Treatment
A drink of radio-active iodine is often required following surgery for thyroid cancer. This has minimal
complications, has been shown to decrease recurrence of thyroid cancer and may be repeated if needed. The
main indication for adjuvant radio-iodine treatment is a high likelihood that the thyroid cancer may recur
and/or an elevated thyroglobulin level.
Thyroglobulin (Tg) is a protein found in the blood that is only produced by the thyroid. An elevated Tg
level following thyroidectomy for thyroid cancer is a very accurate marker of tumour recurrence.
Prior to treatment with radio-iodine a thyroid isotope uptake scan is usually required and during treatment
the patient is kept off thyroxine. Being off thyroxine results in an increase in the blood thyroid stimulating
hormone (TSH) from the pituitary gland and this elevated TSH blood level promotes the uptake of the radio-active
iodine into thyroid cancer cells.
Complications of Thyroid Surgery
All operations involve some risk. Risks specific to thyroid surgery include:
- Nerve Injury
There are two nerves close to the thyroid gland on each side that allow the larynx (voice-box) to function.
If these nerves ( the recurrent laryngeal nerve and the superior laryngeal nerve) are injured during thyroid
surgery the patient may experience some voice change. This is uncommon and most changes are minor and
temporary. Voice change is more common following thyroid surgery for cancer, hyperthyroidism, and following
re-do thyroid surgery.
- Low Calcium Levels
During a total thyroidectomy there is a risk of injuring the para-thyroid glands which are located usually
close to the back of the thyroid, attached to the thyroid. There are two glands on either side (inferior and
superior) and they control the body’s calcium level. If these glands are injured the blood calcium
level may fall. Again this is almost always a temporary problem and the glands usually start to function again
after a few weeks. Transplantation of damaged parathyroid glands into adjacent muscle where they can gain a
new blood supply has resulted in permanent low calcium levels following thyroid surgery being largely a thing
of the past. During periods of temporary low calcium levels the problem is usually readily controlled with
tablets of Calcium and Vitamin D (vitamin D promotes calcium absorption from the gut).
- Bleeding
As with any surgery bleeding may can occur after thyroid surgery. This is rare occurring in approximately
1% of patients. It usually results in neck swelling and may involve the patient returning to the operating
room for control of the bleeding and removal of the blood clot.
- Pain
Thyroidectomy is not usually an especially painful operation. There may be some discomfort with swallowing
and neck movement for a short time. Simple pain relieving medications such as Panadol are usually adequate.
Most patients require 2-3. days in hospital, and resume normal activities in approximately 2 weeks.
The relevant frequency of conditions requiring thyroidectomy are shown in the Table below which summarizes
the Authors experience
| Distribution of the Authors Experience of Thyroidectomies |
| Type of Operation |
Number Performed |
| Total Thyroidectomy for Cancer | 280 |
| Total Thyroidectomy For Benign Disease | 700 |
| Total Thyroidectomy for Toxic Disease | 30 |
| Partial Thyroidectomy for Various Reasons | 1000 |
Parathyroid Surgery
Parathyroid glands are small glands of the endocrine system which are located behind the thyroid and
produce parathyroid hormone. Most humans have four Parathyroid glands: two on either side of the
thyroid one upper and one lower gland bilaterally. They are small, only a few millimeters in size. Occasionally
there may be 5 or more glands, or one may actually be present in the chest, most commonly in the thymus gland
behind the breast bone.
Note the superior parathyroid glands are close to the back of the superior part of the
thyroid, while the inferior parathyroid glands are close to the inferior aspect of the thyroid gland
occasionally arising in the thymus (see b above).
The purpose of the parathyroid glands is to regulate the blood calcium level within a very
narrow range so that nerves, muscles, and brain can function properly. Any decrease in the blood
calcium levels stimulates the parathyroid
glands to release parathyroid hormone into the blood. This in turn results in an increase in the blood
calcium level with the level returning into the normal range.
The major disease of parathyroid glands is over-activity of one or more of the parathyroids
which results in the over-production of parathyroid hormone or “hyper-parathyroidism”. This
abnormality results in an elevation of the blood calcium level called hypercalcaemia.
By far the most common (90% of cases) cause of hyper-parathyroidism is a benign tumour in
one parathyroid gland: a Parathyroid Adenoma.
The next most common situation (9%) is a condition whereby all 4 parathyroid glands are abnormal.
This is called Parathyroid Hyperplasia.
Only rarely is the condition caused by a Parathyroid cancer (<1%).
Primary hyperparathyroidism is quite common: The condition affects women three times more
often than men and becomes progressively more common with age. Approximately 1 woman in every 200 over the
age of 40 yrs has hyper-parathyroidism.
Most patients do not have any symptoms and the condition is diagnosed when the patient has a
blood test that shows a high blood calcium level. Some people do, however, have symptoms and these may include:
aching in the arms and legs, osteoporosis and bone fractures; kidney stones; stomach ulcers and abdominal pain.
In older patients with severe disease mental confusion may occur.
Once a diagnosis of hypercalcaemia is made, other tests are usually required to diagnose
hyperparathyroidism. Most important is the determination of the blood parathyroid hormone level.
In some patients it is also important to check the urine calcium level. Other tests that may be required
include measurement of kidney function and the bone enzyme alkaline phosphatase
Surgery for Hyperparathyroidism
Occasionally drugs are used to temporarily bring down the level of calcium if the level is
very high. The only definitive treatment, however, is surgical removal of the overactive parathyroid gland
or glands. Usually this is a highly successful procedure with a low complication rate.
The object of the operation is to locate and remove the overactive parathyroid tissue
(most commonly one gland as in Fig below).
Minimally Invasive Parathyroidectomy
Pre-operative localization of the overactive gland may be possible by performing an ultrasound
scan and or an isotope scan using the tracer Sestamibi which is taken up by the parathyroid tissue.
If one gland can be identified pre-operatively to be overactive on both the ultrasound and
the sestamibi scans, then a smaller incision can often be possible to the side of the midline of the neck
and a simpler and quicker operation performed. However, if the overactive gland(s) cannot be identified, the
standard operative procedure is to use an incision in the midline of the neck similar to that used for thyroid
surgery and examine all 4 parathyroid glands and remove the abnormal one(s). Again this is a very successful
operation with a low complication rate.
The operative technique involves a low curved neck incision. The thyroid is partially mobilised
to explore one or more parathyroid glands. The enlarged gland(s) is/are removed. Sometimes a frozen section is
performed to confirm the presence of parathyroid tissue. Hospital stay is usually 1-2 days and recovery 1-2 weeks.
Complications of Surgery for Hyperparathyroidism
As with thyroid surgery, the potential complications of surgery for parathyroid disease include:
- Injury to the nerves supplying the larynx (voice-box) resulting in some alteration in voice.
This is rare and usually a temporary problem.
- Bleeding may occur as with any operation. Again this is rare (1% risk) and may require a
return to the operating room for control of bleeding and removal of the blood clot.
- Low calcium levels may occur as may low magnesium levels. Usually these problems are
temporary and can be managed by the patient taking Calcium and/or Magnesium tablets for a few weeks.
Parathyroidectomy for Patients with Renal Failure
Patients with chronic renal (kidney) failure who are on dialysis often develop hyperparathyroidism.
This involves all four parathyroid glands and results in calcium being mobilized out of bones with resultant bone
pain. Parathyroid surgery may be required often depending on the degree of PTH elevation. This type of
parathyroidectomy cannot be performed using minimally invasive surgery and the goal is to remove at least three
and a half parathyroid glands.
