Thyroid Nodules

What are Thyroid Nodules?

Thyroid Nodules are cysts by definition as they are fluid-filled lumps that occur in or on the thyroid gland. The gland is located in between the voice box (larynx) and collar bones. The size of the nodule is less than 1 cm and can be complex containing both solid and fluid substance. This cyst occurs in 6% of women and 2% in men.

Characteristics of Thyroid Nodule

If the nodule is in the outer section, then it can be identified, but if the cyst is located below the gland or hidden by the thyroid tissue, then it is difficult to understand its presence. It has the following characteristics:

  • Single or multiple
  • Becomes a cyst when it contains fluid or blood
  • Presence of multi-nodular goiter contains numerous nodules
  • If the bulge is ‘hot’ it will secrete thyroid hormone but if its ‘cold’ then it does not secrete any hormone

Causes

The reasons for the development of thyroid nodule are as follows:

Overgrowth of normal thyroid tissue

The reason behind the sudden increase is unclear. Thyroid adenoma (autonomous or hyperfunctioning thyroid nodule) is benign which produces thyroid hormones that are secreted outside the pituitary gland’s regular regulatory influence leading to excessive production of thyroid hormones (hyperthyroidism).

Lack of iodine

Iodine is an essential part the diet, but if there is a shortage, it may cause thyroid nodules.

Multinodular goiter

The term ‘goiter’ is used to describe an enlarged part of the thyroid gland which can be due to thyroid disorder or iodine deficiency. Its cause is less apparent, although multinodular goiter contains multiple nodules inside the goiter.

Hashimoto’s  thyroiditis

Hashimoto thyroiditis is an auto-immune condition within the body’s immunization system that affects the thyroid gland. It causes inflammation in the thyroid gland which results in increased size of the nodule.

Thyroid cancer

Thyroid nodules have only 5% chance of turning into cancer, but there are some risk factors involved such as heredity thyroid, other endocrine cancers, the age of a person, history of radiation exposure, discomfort or pain if it is malignant.

Thyroid Cyst

Thyroid cysts are filled with blood or fluid which is a typical result of thyroid adenomas. Sometimes these cysts get mixed up with some solid components making it partly cancerous.

Risk Factors

  • Age of a person
  • Family history
  • Exposure to radiation
  • Gender

Symptoms

  • Feel of its presence
  • Pain in the neck
  • Trouble while swallowing
  • Voice change or hoarseness

Extra thyroxin in the thyroid can cause hyperthyroidism which shows signs of:

  • Tremor
  • Unexpected weight loss
  • Difficulty in sleeping
  • Thinning hair
  • Heat sensitivity
  • Heart palpitation
  • Nervousness
  • Increase or decrease in appetizer
  • Abnormal menstrual cycle
  • Eye irritation and vision problems

Diagnosis

The thyroid nodules are usually discovered during imaging tests, but it is not possible to determine by physical examination or blood test if the cyst is cancerous. If the thyroid nodule is discovered, the doctor tries to find out if the cyst has affected the entire thyroid gland with the condition of hyperthyroidism or hypothyroidism.

Thyroid Hormonal Test

Blood tests that show any abnormal high or low level of thyroid hormones and thyroid-stimulating hormone in the body.

Thyroid Fine Needle Aspiration Biopsy

A simple procedure, it can be conducted in the physician’s chamber itself. In this method, local anesthesia is given to the patient. With the help of a small needle, one or more cells from the nodule are taken out for laboratory test. Sometimes before this process, medications like blood thinners may need to be stopped for a few days, otherwise, no special preparation (no fasting) may be required. The report of a fine needle biopsy usually indicates

  1. Nodule is non-cancerous
  2. Nodule is malignant (cancerous) or semi-malignant
  3. Nodule is indeterminate, i.e., with few some cells may be the detection was not possible
  4. Biopsy may be inadequate or non-diagnostic

Thyroid Ultrasound

An imaging test, it uses high-frequency sound waves that penetrate through the skin and reflects back to the machine giving a detailed image of the gland. It determines the nature of the cyst (if it is stable or fluid) and even the size of the nodule. The method also helps in guiding during a needle biopsy. Usually, ultrasound is done to keep an eye on the thyroid nodule if it is shrinking or growing over time.

Nuclear Thyroid Scan

Nuclear thyroid scan was frequently done in the past, but after the introduction of needle biopsy and thyroid ultrasound, thyroid scan is no longer considered as a first-line method of evaluation. In this process, a small amount of radioactive iodine is given to the patient orally or through injection. After that, a computer screening of the thyroid gland is done through a camera where nodules which produce excess hormones called hot nodules are seen because they intake more isotopes than healthy tissues of the thyroid does. Cold buds appear as holes or defects during the scanning process. The advantage of this technique is that it helps in distinguishing between a malignant and benign nodule.

Molecular Diagnostics

The molecular diagnostic is a new test that examines the genes in the DNA of thyroid cyst that is currently available or being developed. The diagnosis is preferable when the evaluation by the pathologist is insufficient. The availability of this test is increasing rapidly and it gives an accurate result.

Complications

  • Hyperthyroidism: When the thyroid gland produces thyroid hormones, it causes hyperthyroidism which creates challenges for a body like weight loss, heat intolerance, muscle weakness, irritability or anxiousness, weak bones (osteoporosis), irregular heartbeat (atrial fibrillation) and thyrotoxic crisis.
  • Problems in swallowing or breathing: Thyroid gland containing a large number of nodules can pose difficulty in eating or breathing.
  • Problems associated with thyroid cancer: Thyroid nodule can cause thyroid cancer which requires surgery and the thyroid gland is removed and replaced.

Treatments

Benign nodules

  • Watchful waiting: If the thyroid nodule is benign in nature, then doctors may just examine the cyst with a physical exam or some regular test.
  • Thyroid hormone suppression therapy: Levothyroxine, a synthetic type of thyroxine that is taken in a pill form when the cyst is benign. This pill signals the pituitary gland to secrete less amount of TSH which further reduces the growth of thyroid tissue.
  • Surgery: Sometimes a nodule which is benign, requires surgery if its size creates an issue in swallowing or breathing. Surgery is also necessary if many goiters restrict the passage of blood vessels or esophagus.

Nodules that cause Hyperthyroidism

  • Radioactive iodine: It is used to treat multinodular goiter or hyperfunctioning adenomas. They can be swallowed or injected into the vein in the arm. This causes the nodule to shrink and reduces the symptoms of hyperthyroidism.
  • Anti-thyroid medications:  Methimazole (tapazole) medication is used to reduce the symptoms of hyperthyroidism, but it can have side effects which may harm the liver so consulting a doctor is important.
  • Surgery: If the radioactive iodine or anti-thyroid medication isn’t helping, an operation is the only option to finish the signs of hyperthyroidism.

Cancerous Nodules

  • Surgery: The procedure for the removal of malignant nodule through operation is called near-total thyroidectomy, but it involves the risk of damaging vocal cords and parathyroid glands. After the surgery, the patient requires a lifetime treatment with levothyroxine to supply normal amount of thyroid hormones to the body.
  • Alcohol ablation: Alcohol ablation is another method to remove a cancerous cyst from the thyroid. A small amount of alcohol is inserted into the cancerous thyroid nodule. This process is helpful for areas where it is difficult to do surgery and it requires multiple sessions.

Thyroid Cyst Nodules

According to American Thyroid Association, 90% of the thyroid nodules are benign, but if it is malignant, it can be treated easily depending on the type of disorder. If the diagnosis is done in the early stages, then the prognosis of well-differentiated cancer will be easy, but if there is a poorly differentiated cancer, then it is hard to treat.

In 2013, 637,115 people were suffering from thyroid cancer in the United States and 2006 to 2012, 98.1% were diagnosed with a malignancy in the thyroid gland and they survived for at least five years.

References

 

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