THYROID SURGERY, THYROID DISEASES, AND SURGICAL TREATMENT (GUATR)

What is the thyroid gland and where is it located?

The thyroid gland is named after the Greek word for “shield” due to its resemblance to the large cartilage forming the larynx. It is located just below and in front of the larynx, along the midline, where it is adjacent to this cartilage. The thyroid gland consists of right and left lobes that join in the middle. In front of this gland, there are muscle groups and the skin of the neck extending from top to bottom. This organ has a richer blood supply than many other body tissues and releases the hormones it secretes into the bloodstream through these blood vessels, regulating metabolism. These vital hormones are transported via the blood to all body tissues, regulating metabolism.

How can you determine if the thyroid gland is functioning properly?

The best indicator of thyroid gland function comes from the Thyroid-Stimulating Hormone (TSH) released by the pituitary gland in the brain. This hormone stimulates the hormone-secreting structures in the thyroid gland to produce and release more hormones into the blood. When the thyroid gland is underactive, the release of TSH into the blood increases. Conversely, if the thyroid gland starts producing more hormones on its own, the pituitary gland reduces TSH production, resulting in TSH levels below the normal range when measured in the blood. In addition to TSH, measuring free T4 (FT4) and free T3 (FT3) hormones can provide information about thyroid function in certain cases and may be requested by your physician from the laboratory.

What happens if the thyroid gland is underactive?

When the thyroid gland is underactive and cannot secrete enough thyroid hormones necessary for body tissues, this condition is called hypothyroidism. In this case, the levels of thyroid hormones in the blood decrease, and insufficient hormones reach the tissues. Body functions slow down, the patient becomes more easily cold, quickly fatigued, and experiences symptoms such as weight gain, hair loss, dry skin, constipation, and forgetfulness. Hypothyroidism most commonly occurs due to autoimmune thyroiditis, where the body’s immune system attacks the thyroid gland, thyroid removal due to cancer or other reasons, or as a result of radioactive iodine (atom) therapy. This condition usually persists for life, requiring the patient to take thyroid hormone orally in pill form and to be monitored by an endocrinologist (hormone specialist) throughout their life.

What happens if the thyroid gland is overactive?

An overactive thyroid gland, secreting excessive amounts of thyroid hormones, is known as hyperthyroidism. Excess thyroid hormones reaching the tissues cause an increase in all bodily functions. Symptoms include increased heart rate, palpitations, tremors in the hands, sweaty skin, irritability, restlessness, and weight loss without loss of appetite. One of the most common causes of hyperthyroidism is Graves’ disease, which, in addition to the symptoms mentioned, causes the eyes to appear excessively large and protruding due to the wide opening of the eyelids.

Other causes of hyperthyroidism include toxic (poisonous) nodular goiter (a thyroid with one or more nodules) and thyroiditis. Treatment for this condition can be performed in three ways:

  • Using oral medications to eliminate the effects of excess thyroid hormones,
  • Radioactive iodine (atom) therapy to destroy the overactive thyroid tissue and reduce hormone secretion,
  • Surgical removal of the thyroid gland entirely or almost entirely.
  • What is a goiter? A goiter refers to the enlargement of the thyroid gland. This can be due to cancer or insufficient iodine intake in the diet, or consumption of goiter-causing foods like cassava. When the entire thyroid gland enlarges uniformly, it is called a diffuse goiter. When nodules are present within the thyroid gland, it is referred to as a multinodular goiter. With the development of devices that create images by recording the reflections of sound waves sent into body tissues (ultrasound), nodules that were previously undetectable are now often classified as multinodular goiters.

What is a thyroid nodule?

A thyroid nodule is a mass formed by the enlargement of certain areas of cells within the thyroid gland, creating a lump with different density and firmness compared to other parts of the thyroid. Nodules can exist as single nodules (solitary thyroid nodule) or multiple nodules within the thyroid (multinodular goiter). Additionally, nodules are categorized based on their content into solid nodules (non-fluid-filled) and cystic nodules (fluid-filled).

In a medical imaging method called thyroid scintigraphy, where a small amount of radioactive substance is administered, nodules are classified as cold nodules (non-functioning) and hot nodules (functioning). Most nodules do not produce any symptoms and are only noticeable when they become large enough to be detected by the patient. Very large nodules can cause noticeable swelling in the patient’s neck, which can be easily detected by others. Large nodules can also press on the pale and esophagus, leading to symptoms. Overactive nodules are a cause of hyperthyroidism as mentioned above. Ultrasound examinations can detect nodules as small as millimeters, which are not detectable through manual examination by the physician. However, nodules smaller than 10 millimeters generally do not cause significant concern. The clinical significance of nodules lies in their potential to harbor cancer. Various studies have reported that 5-10% of nodules are malignant. This risk increases in certain situations, such as in children, men, elderly patients, those who have undergone radiation therapy to the head and neck for any reason during childhood, and in patients with nodules accompanied by hoarseness or enlarged lymph nodes in the neck. Evaluating nodules involves not only physical examination but also measuring thyroid hormones (T3, T4, and TSH), performing fine-needle biopsy of the nodules, and using ultrasound to examine the nodules, remaining thyroid tissue, and neck.

When is thyroid surgery performed?

Thyroidectomy, the surgical removal of the thyroid gland, is generally performed under the following conditions:

  • Confirmation or suspicion of cancer in a nodule,
  • The thyroid gland or nodule pressing on the esophagus and respiratory tract, causing swallowing and breathing difficulties,
  • Excessive enlargement of the thyroid gland or nodule causing cosmetic concerns,
  • The thyroid gland or nodule causing excessive hormone secretion leading to hyperthyroidism.

What should be considered during thyroid surgery?

Due to the close proximity of the thyroid gland to the vocal nerve in the larynx and the beginning of the trachea, damage to these nerves can lead to significant voice changes, including hoarseness. Additionally, on the posterior surface of the thyroid, there are four parathyroid glands (each about the size of a pea) located on both sides. These glands regulate blood calcium levels by secreting hormones. For maintaining proper blood calcium levels, at least two of these glands need to function correctly. However, in cases where thyroid surgery involves removing both sides of the thyroid gland, there is a risk of inadvertently removing or damaging the blood supply to all four parathyroid glands, resulting in decreased blood calcium levels. This can cause numbness around the hands, feet, and lips, muscle contractions, and cramps in the arms and legs. In cases of temporary calcium deficiency, oral or intravenous calcium medications are sufficient, while permanent hormone deficiency and calcium deficiency require the administration of both calcium and vitamin D. Preserving these critical structures and preventing their damage during surgery is of utmost importance. The surgeon’s primary goal should be to remove the thyroid gland while protecting these vital structures. Experienced surgeons using correct surgical techniques significantly reduce the likelihood of permanent complications.

What surgical technique should be applied to the patient? Sometimes, the issue within the thyroid gland (e.g., nodular goiter or overactive nodule) may be limited to one lobe. In such cases, removing only the affected side of the thyroid gland is sufficient. However, sometimes intraoperative pathology examinations may indicate the need to remove the entire thyroid gland. In some cases, problems exist on both sides of the thyroid gland, necessitating the complete removal of the thyroid gland. Rarely, a small portion of the thyroid gland may be left behind to avoid compromising the upper blood vessels or due to other technical reasons. However, if the patient has thyroid cancer, the surgeon typically prefers removing the entire thyroid gland.

In conclusion, contemporary thyroid surgery practices involve removing the entire thyroid gland on the affected side, except in certain exceptions. Not performing a complete thyroidectomy can lead to the following disadvantages:

  • If the disease (e.g., nodular goiter) recurs on the operated side in the future, performing surgery on the same side again will be more difficult and carry a higher risk of complications during the second surgery.
  • If the patient has thyroid cancer, the measurement of thyroglobulin—a substance secreted by both healthy and cancerous thyroid cells—after surgery can help detect recurrences early. If thyroid tissue is left behind, it becomes impossible to determine whether the detected thyroglobulin is due to a recurrence or residual thyroid tissue. Therefore, this valuable recurrence marker cannot be used in such patients.
  • Additionally, many thyroid cancers require radioactive iodine (atom) therapy post-surgery. Leaving thyroid tissue behind poses a significant disadvantage in terms of both follow-up and potential radioactive iodine treatment. Patients who have had their entire thyroid gland removed are in a better position for both post-surgical follow-ups and radioactive iodine therapy.