THYROID

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Context

• World Thyroid Day is observed on May 25thevery year.

Details

Theme for 2024

• The theme for World Thyroid Day 2024 is Non-Communicable Diseases (NCDs).
• This theme underscores the significant contribution of thyroid disorders to global health concerns, as thyroid issues are a major subset of non-communicable diseases.

History

• 1965: The European Thyroid Association (ETA) was founded, marking a significant step in the recognition and study of thyroid health.
• 2007: The Thyroid Federation International (TFI) established May 25th as World Thyroid Day. This date was selected to coincide with the anniversary of the ETA, highlighting the importance of international cooperation in thyroid health.

About Thyroid Gland

• The thyroid gland is a vital endocrine organ located in the neck.
• It plays a crucial role in regulating metabolism, growth, and development through the secretion of thyroid hormones.

Anatomy of the Thyroid Gland

• Location: The thyroid gland is located in the anterior part of the neck, below the larynx and in front of the trachea.
• Structure:
  • Lobes: The thyroid gland consists of two lateral lobes connected by a thin isthmus.
  • Capsule: Enclosed in a fibrous capsule that further divides the gland into lobules.
  • Blood Supply: Richly supplied by the superior and inferior thyroid arteries.
  • Innervation: Innervated by sympathetic and parasympathetic fibers.

Physiology of the Thyroid Gland

• Hormone Production:
  • Thyroxine (T4): The major hormone produced, which is converted to the more active triiodothyronine (T3) in peripheral tissues.
  • Triiodothyronine (T3): The active form of thyroid hormone, which exerts the physiological effects.
• Regulation:
  • Hypothalamus-Pituitary-Thyroid Axis: The hypothalamus releases thyrotropin-releasing hormone (TRH), stimulating the pituitary to release thyroid-stimulating hormone (TSH), which in turn stimulates the thyroid gland to produce T3 and T4.
  • Feedback Mechanism: T3 and T4 levels in the blood provide feedback to the hypothalamus and pituitary to regulate hormone production.

Functions of Thyroid Hormones

• Metabolic Regulation: Increases basal metabolic rate, influences protein synthesis, and stimulates carbohydrate and fat metabolism.
• Growth and Development: Essential for normal growth and development, particularly of the nervous system.
• Cardiovascular Effects: Increases heart rate and cardiac output.
• Thermoregulation: Helps maintain body temperature.

Common Thyroid Disorders

• Hypothyroidism:
  • Causes: Hashimoto's thyroiditis, iodine deficiency, thyroidectomy, certain medications.
  • Symptoms: Fatigue, weight gain, cold intolerance, constipation, depression, dry skin.
  • Diagnosis: Elevated TSH, low T4 and T3 levels.
  • Treatment: Levothyroxine replacement therapy.
• Hyperthyroidism:
  • Causes: Graves' disease, toxic multinodular goiter, thyroid adenoma.
  • Symptoms: Weight loss, heat intolerance, increased appetite, palpitations, anxiety, tremors.
  • Diagnosis: Low TSH, elevated T4 and T3 levels.
  • Treatment: Antithyroid medications (e.g., methimazole), radioactive iodine therapy, thyroidectomy.
• Goiter:
  • Causes: Iodine deficiency, Hashimoto's thyroiditis, Graves' disease.
  • Symptoms: Visible enlargement of the thyroid gland, swallowing difficulties, breathing problems.
  • Diagnosis: Clinical examination, ultrasound, thyroid function tests.
  • Treatment: Depends on the underlying cause; may include iodine supplementation, thyroid hormone replacement, or surgery.
• Thyroid Nodules:
  • Causes: Benign adenomas, cysts, thyroid cancer.
  • Symptoms: Often asymptomatic, may cause swallowing or breathing difficulties if large.
  • Diagnosis: Ultrasound, fine-needle aspiration biopsy, thyroid function tests.
  • Treatment: Observation, surgery, radioactive iodine therapy.
• Thyroid Cancer:
  • Types: Papillary, follicular, medullary, anaplastic thyroid cancer.
  • Symptoms: Lump in the neck, difficulty swallowing, hoarseness, swollen lymph nodes.
  • Diagnosis: Ultrasound, fine-needle aspiration biopsy, imaging studies (CT, MRI), thyroid function tests.
  • Treatment: Surgery, radioactive iodine therapy, external radiation therapy, chemotherapy.

Sources:

TelegraphIndia

PRACTICE QUESTION Q. Consider the following statements about the thyroid gland: The thyroid gland is located in the neck, below the larynx and in front of the trachea. Thyroxine (T4) is the only hormone produced by the thyroid gland. The thyroid gland regulates metabolism, growth, and development. Which of the above statements is/are correct? a) 1 and 2 only b) 2 and 3 only c) 1 and 3 only d) 1, 2, and 3 Answer: c)