About Thyroid

The thyroid gland is located in front of the trachea and is an endocrine gland. It is composed of two lobes joined by an isthmus. The superior thyroid artery and inferior thyroid artery, which are branches of the external carotid artery and subclavian artery, respectively, supply the thyroid with blood. There are four parathyroid glands located behind the thyroid gland and regulate calcium levels in the circulation. The recurrent laryngeal nerve (a branch of the vagus nerve, the eleventh cranial nerve in humans) also traverses the tracheoesophageal groove behind the thyroid gland. In order to avoid postoperative complications such as hoarseness, the surgeon must therefore be careful not to damage this nerve during surgery. 


The thyroid gland's function is to produce thyroid hormones, which are essential for maintaining the metabolic functions of the body. Thyroid hormones are hormones that stimulate the production of proteins by our cells. They have a direct impact on the metabolism as well as the function and activity of numerous organs. Thyroid hormones regulate heart rate, blood pressure, digestion, appetite, mood, bone metabolism, menstrual cycles, metabolism, and muscle control. Both excessive secretion (hyperthyroidism) and insufficient secretion (hypothyroidism) of thyroid hormones can have significant effects on numerous body organs.


There are two varieties of thyroid hormones: thyroxine (T4) and triiodothyronine (T3). Iodine is required for the production of both T4 and T3. Iodine deficiency is uncommon in Hong Kong because iodine is commonly obtained through the consumption of iodized salt. However, iodine deficiency-related thyroid disorders are more prevalent in mountainous regions.


Classification of thyroid diseases

Thyroid hormone secretion is regulated by thyroid-stimulating hormone (TSH). Under normal circumstances, TSH is secreted by the pituitary gland and travels through the bloodstream to the thyroid. It then stimulates the thyroid gland to produce thyroid hormones T3 and T4. The secretion of thyroid hormones is tightly regulated by the body’s feedback mechanism. If thyroid hormone secretion is excessive, the pituitary gland reduces TSH secretion, leading to a decrease in thyroid hormone production, and vice versa. This feedback mechanism helps maintain thyroid hormone secretion at normal levels. If there are issues with this feedback mechanism, it can result in thyroid dysfunction.


Hyperthyroidism (Overactive Thyroid)

Graves disease is the most prevalent cause of hyperthyroidism. In Graves' disease, the immune system stimulates the secretion of thyroid hormone (T4). This uncontrolled secretion causes an accelerated metabolism in numerous organs, resulting in symptoms such as a rapid heart rate, palpitations, and weight loss.


Hypothyroidism (Underactive Thyroid)

In contrast, if thyroid hormone production decreases for a variety of reasons (the most common being Hashimoto's thyroiditis or post-surgical or post-radioiodine treatment-induced hypothyroidism), causing low metabolic rate. Patients with h Hypothyroidism usually present with slow heartbeat, appetite decline, weight gain, and constipation. Hypothyroidism, if left untreated, can result in complications such as cardiovascular diseases due to elevated levels of harmful cholesterol in the blood, caused by a decreased cholesterol metabolism in the liver.


Surgical Disease of Thyroid

Thyroid surgical conditions include thyroid cysts, thyroid nodules, and thyroid malignancy. These conditions are unrelated to thyroid hormone secretion, so patients' thyroid hormone levels are normal.


Patients frequently seek medical attention due to neck swelling (goiter). The physician will arrange an ultrasound of the thyroid to ascertain the cause of the goiter. The ultrasound assists the physician in distinguishing between thyroid cysts, nodules, and thyroid malignancy. In some instances, the doctor may also arrange an ultrasound-guided fine-needle aspiration in which cells from the thyroid cyst or nodule are extracted for analysis to determine the underlying cause.


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What is hyperthyroidism?
What is hyperthyroidism?

Thyroid hormones, which are produced by the thyroid gland, an endocrine gland in our body, are vital for sustaining our body's metabolic processes. Thyroid hormones stimulate cells to produce proteins, which have a direct impact on our metabolism as well as the operations of different organs. As a result, our heart rate, blood pressure, digestion, appetite, mood, menstrual cycle, metabolism, and muscle control are all impacted by the level of thyroid hormones. Too much thyroid hormone (hyperthyroidism) or too little thyroid hormone (hypothyroidism) can have a substantial impact on the majority of our body's organs.


The term "hyperthyroidism" describes the thyroid gland's excessive release of thyroid hormones (T4 or T3) for a variety of causes. This causes different body organs to have faster metabolism and produces a variety of clinical symptoms.

Causes of hyperthyroidism
Causes of hyperthyroidism
  1. Graves' disease: The most typical cause of hyperthyroidism. With autoimmune dysfunction, patients produce aberrant antibodies that assault and trigger the TSH receptor on thyroid cells, increasing thyroid hormone synthesis and secretion.
  2. Toxic adenoma: Thyroid hormones are produced and secreted in an unregulated manner as a result of abnormal thyroid cell development.
  3. Toxic Multinodular Goitre: Hyperthyroidism can result from a multinodular goitre that has been present for a long time.
  4. Thyroiditis: Thyroiditis in its early stages results in the release of thyroid hormones from storage into the bloodstream, which leads to hyperthyroidism.
  5. Causes brought on by drugs, such as the arrhythmia medicine amiodarone.
  6. Excessive intake of iodine.
  7. Other uncommon reasons include pituitary tumors, ovarian or testicular tumors that release thyroid hormones, etc.
Symptoms of hyperthyroidism
Symptoms of hyperthyroidism

Patients receive faster body metabolism as a result of high thyroid hormone release, and symptoms include:

  • Rapid heartbeat
  • Palpitations
  • Irritability
  • Depression
  • Insomnia
  • Increased appetite but significant weight loss
  • Menstrual irregularities
  • Diarrhoea
  • Tremors in the hands
  • Heat intolerance
  • Excessive sweating
Diagnosis of hyperthyroidism
Diagnosis of hyperthyroidism

Clinical Examination

Doctors might enquire about a patient's medical history, family history, and associated symptoms during a physical examination and clinical assessment. Clinical palpation enables medical professionals to ascertain the presence of additional nodules or enlarged lymph nodes in the neck, whether the trachea is squeezed as a result of thyroid enlargement, whether the patient has thyroid enlargement, and whether the enlargement is uniform and symmetrical.


Blood Tests: Thyroid Function Tests

Blood tests can be used to determine thyroid function tests, which measure the body's thyroid hormone output. Triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) are all measured during thyroid function tests.


Thyroid Ultrasound

Thyroid ultrasound is a non-invasive examination. Gel is applied to the patient's neck during the procedure, and an ultrasound probe is used to capture live thyroid images. During the examination, the doctor takes matching photos for analysis. With the use of a thyroid ultrasound, a doctor can determine the size of the thyroid, the size and type of thyroid nodules, the blood flow around the nodules, calcifications, and whether or not there are enlarged neck lymph nodes, among other things.

Beware of thyroid storm and its consequences
Beware of thyroid storm and its consequences

A potentially fatal condition is thyroid storm. When a person who has uncontrolled or inadequately treated hyperthyroidism is exposed to certain triggers, such as trauma, illness, or surgery, it happens.


High fever, a rapid heartbeat, high blood pressure, nausea, an enlarged liver, jaundice, restlessness, and trembling are all signs of thyroid storm. Without prompt medical attention, complications like cardiac failure, coma, arrhythmias, or mental confusion may develop, which might be fatal.


Patients with hyperthyroidism may also encounter the following side effects in addition to thyroid storm:

  1. Eye complications: Long-term eye protrusion can cause damaged corneas, partial eyelid closure, and even blindness.
  2. Psychiatric complications: Psychological side effects of hyperthyroidism include emotional instability, anxiety, sleeplessness, agitation, or depression.
  3. Metabolic abnormalities: Metabolic diseases including diabetes and liver dysfunction can be brought on by hyperthyroidism.
  4. Digestive problems: Patients may experience diarrhoea and indigestion.
  5. Osteoporosis: Excessive thyroid hormone secretion accelerates bone resorption, increasing the risk of osteoporosis and fractures.
  6. Cardiac complications: Heart failure and other cardiac problems can result from long-term hyperthyroidism-related tachycardia and arrhythmias.
  7. Infertility and miscarriage: Hyperthyroidism may increase the risk of female infertility, miscarriage, and premature birth.


To avoid thyroid storm and lower the risk of consequences, it is crucial that individuals with hyperthyroidism receive the right care and management. For the illness to be adequately controlled, regular medical follow-up and adherence to recommended drugs are essential.

Treatment of hyperthyroidism
Treatment of hyperthyroidism

Before determining the appropriate treatment, the doctor must identify the underlying cause of the patient's condition.


Medical Treatment

Medication is the most common treatment for hyperthyroidism. Anti-thyroid medications suppress the production of thyroid hormones, restoring normal thyroid secretion and metabolism in the patient. Initiating medication requires close monitoring of thyroid hormone levels, and the dosage will be adjusted until thyroid hormone levels are within the normal range. Carbimazole and Propylthiouracil are two commonly used anti-thyroid pharmaceuticals.


Some patients may experience allergic reactions, such as irritation or rashes, to the medication. Other possible complications include transient liver dysfunction. In such situations, the patient may be prescribed different medication or other alternative treatment options.


It is essential for patients to adhere to their prescribed medication regimen and maintain regular follow-up appointments with their doctor so that their condition can be monitored and treated as necessary. Depending on the individual's condition and response to treatment, medication may be combined with other treatment modalities such as radioactive iodine therapy or surgery.

Is goiter= hyperthyroidism?
Is goiter= hyperthyroidism?

The thyroid glands are typically around 3 and 4 cm long and are located on both sides of the neck, below the Adam's apple. As soon as the thyroid glands reach a height of 5 to 6 cm, the neck will expand and protrude, which can be felt with the hand. As the expansion of the thyroid glands comes into contact with the collarbones, the opening of the neck becomes constricted. As the growth tissues continue to expand, they may exert pressure on the trachea and impair respiration. 


Goiter is a condition in which the thyroid gland is enlarged, patients can undergo a minimally invasive thyroidectomy to remove the growth tissues.

The Lymphatic System

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