The thyroid is a butterfly-shaped gland located in the front of the neck, just below the larynx. It is part of the endocrine system and produces hormones, primarily thyroxine (T4) and triiodothyronine (T3), which regulate the body’s metabolism, energy levels, and overall growth and development. The thyroid also plays an important role in controlling body temperature, heart rate, and calcium levels in the blood.

Contents
Thyroid Gland hormones: Roles and Functions Explained
The thyroid gland secretes three main hormones:
1. Thyroxine (T4): The primary hormone produced by the thyroid, it acts as a precursor to triiodothyronine. It is less active but can be converted into T3 in the body’s tissues.
2. Triiodothyronine (T3): The active form of thyroid hormone, it regulates metabolism, growth, and development.
3. Calcitonin: A hormone involved in calcium homeostasis. It helps to lower blood calcium levels by inhibiting the activity of osteoclasts, the cells that break down bone and increase the intake of calcium in bone.
The thyroid gland plays a crucial role in regulating several body functions, primarily through the secretion of hormones. Its main functions include:
1. Metabolism Regulation:The thyroid hormones (T3 and T4) increase the metabolic rate, influencing how the body converts food into energy.
2. Growth and Development:Thyroid hormones are essential for normal growth and development, particularly in children. They help in the development of the brain and skeletal system.
3. Temperature Regulation: Thyroid hormones help in controlling the body temperature by affecting the rate of metabolism.
4. Heart Rate and Cardiovascular Function: These hormones affect heart rate and the strength of heart contractions, thus influencing overall cardiovascular health.
5. Calcium Homeostasis: The hormone calcitonin, produced by the thyroid, helps regulate calcium levels in the blood by inhibiting bone resorption.
Overall, the thyroid gland ensures that the body’s various systems function optimally by regulating energy production and utilisation and imbalance in this hormone results into dysfunctionality of organs lead to Thyroid disease mainly hypothyroidism and hyperthyroidism.
Hypothyroidism: A Comprehensive Guide to Thyroid Disease
Hypothyroidism is a thyroid disease where the thyroid gland is underactive and does not produce enough thyroid hormones (primarily thyroxine or T4 and triiodothyronine or T3). This deficiency can lead to a slowing down of the body’s metabolic processes.
What Causes Hypothyroidism? Common Factors and Risks
The pathophysiology of hypothyroidism involves a complex interplay between the thyroid gland, the pituitary gland, and the hypothalamus. Here’s a detailed overview:
- Primary Hypothyroidism: The most common form, resulting from intrinsic dysfunction of the thyroid gland.
- Hashimoto’s Thyroiditis: An autoimmune condition where the immune system attacks thyroid tissue, leading to inflammation and destruction of thyroid cells. This leads to decreased production of thyroid hormones (T3 and T4).
- Iodine Deficiency: Iodine is important for synthesis of thyroid hormone synthesis. Inadequate iodine intake leads to reduced hormone production.
- Thyroidectomy or Radiation Therapy: Surgical removal or radiation treatment for thyroid or other cancers can lead to hypothyroidism by removing or destroying thyroid tissue.
- Medications: Certain drugs can impair thyroid hormone production or function.
In primary hypothyroidism, low levels of T3 and T4 result in increased TSH production by the pituitary gland due to lack of negative feedback.
- Secondary Hypothyroidism: Caused by insufficient stimulation of the thyroid gland due to a problem in the pituitary gland.
- Pituitary Disorders: Tumours, surgery, or radiation affecting the pituitary gland can result in reduced secretion of thyroid-stimulating hormone (TSH), leading to decreased thyroid hormone production.
- Tertiary Hypothyroidism: Resulting from hypothalamic dysfunction.
- Hypothalamic Disorders: Damage to the hypothalamus due to tumours, trauma, or other conditions can impair the release of thyrotropin-releasing hormone (TRH), which in turn reduces TSH production from the pituitary and decreases thyroid hormone production.
Tired and Cold? Check for Hypothyroidism Symptoms
- Fatigue and weakness
- Weight gain
- Cold intolerance
- Dry skin and hair
- Constipation
- Depression
- Memory problems
- Muscle aches and joint pain
- Menstrual irregularities in women
Decreased thyroid hormone levels slow metabolic processes, leading to symptoms like fatigue, weight gain, cold intolerance, constipation, dry skin, and bradycardia.
Accumulation of glycosaminoglycans (such as hyaluronic acid) in tissues can cause myxedema, characterised by swelling and thickening of the skin and other tissues.
Early Detection of Hypothyroidism: Importance of Diagnosis
- Blood Tests: Measurement of TSH, T3, and T4 levels.
- In Hypothyroidism, High level of TSH is detected, as the pituitary gland produces more TSH to stimulate the underactive thyroid.
- Low level of T4 confirm in Hypothyroidism
- Thyroid peroxidase antibodies (TPOAb) and Thyroglobulin Antibodies (TgAb) may be checked if Hashimoto’s thyroiditis is suspected.
Hypothyroidism Treatment Options: Managing Your Condition
- Administration of levothyroxine, a synthetic form of thyroxine (T4). In some cases, liothyronine, a synthetic form of T3, may be added to levothyroxine therapy in the patients who do not respond adequately to T4. However, combination therapy is less common.
- Some patients use NDT ( Natural Desiccated Thyroid), which is derived from the thyroid glands of pigs and contains both T3 and T4.
- Avoid taking antacids containing aluminium, calcium supplements, and certain cholesterol lowering drugs can interfere with the absorption of levothyroxine.
- Iron supplement, calcium supplement, soy, and high-fibre foods are taken several hours apart from thyroid medication.
Control Hyperthyroidism: Symptoms, Causes, and Treatment
Hyperthyroidism is a thyroid disease where the thyroid gland produces too much thyroid hormone, leading to an overactive metabolism. This can cause a range of symptoms and complications if not managed properly.
Causes of Hyperthyroidism: What Triggers Overactive Thyroid?
1. Graves’ Disease: An autoimmune disorder and the most common cause, where the immune system attacks the thyroid, causing it to enlarge and overproduce hormones.
2. Thyroid Nodules: Benign lumps in the thyroid can become overactive and produce excess hormones.
3. Thyroiditis: Inflammation of the thyroid gland, which can cause temporary hyperthyroidism.
4. Excessive Iodine: Too much iodine in the diet or medications can lead to overproduction of thyroid hormones.
5. Medications: Taking too much synthetic thyroid hormone can cause hyperthyroidism.
Hyperthyroidism: Recognizing the Symptoms
- Rapid heartbeat or palpitations
- Unintentional weight loss
- Increased appetite
- Nervousness, anxiety, or irritability
- Tremors (shaking hands or fingers)
- Sweating and heat intolerance
- Increased bowel movements
- Fatigue and muscle weakness
- Difficulty sleeping
- Changes in menstrual patterns in women
- Enlarged thyroid gland (goiter)
- Osteoporosis

Accurate Hyperthyroidism Diagnosis: Essential Tests
- Blood Tests: Measurement of TSH, T3, and T4 levels.
- Low or undetectable TSH levels suggest hyperthyroidism, as the thyroid gland is producing excess hormones and suppressing TSH production
- High level of T4 and T3 confirm hyperthyroidism
- TRAb (Thyrotropin Receptor Antibodies) and TgAb may be checked if Grave’s disease is suspected.
- Radioactive Iodine Uptake Test: Measures the amount of iodine the thyroid gland absorbs from the bloodstream.
- Thyroid Scan: Imaging to observe the structure and function of the thyroid gland.
Manage Hyperthyroidism: Treatment Plans and Lifestyle Changes
- Medications:
- Antithyroid Medications: Such as methimazole or propylthiouracil, which decreases the production of thyroid hormones.
- Beta-Blockers: Such as propranolol, which helps control symptoms like rapid heart rate and tremors but do not affect thyroid hormone levels.
- Radioactive Iodine Therapy: Radioactive iodine is taken orally and absorbed by the thyroid gland, destroying overactive thyroid cells. This often leads to hypothyroidism, which is then managed with thyroid hormone replacement.
- Surgery (Thyroidectomy): Partial or total removal of the thyroid gland, usually considered when other treatments are not suitable. Post-surgery, patients typically need lifelong thyroid hormone replacement therapy.
- Lifestyle Modification
- Regular monitoring of thyroid function.
- Healthy diet and adequate hydration.
- Stress management techniques.
- Regular follow-up with a healthcare provider.
Effective management of thyroid disease in both hypothyroidism and hyperthyroidism involves a combination of medical treatment, lifestyle adjustments, and regular monitoring to ensure optimal thyroid function and overall health.
Reference
https://cris.unibo.it/handle/11585/625081
https://cris.unibo.it/handle/11585/625081
https://www.medical.theclinics.com/article/S0025-7125(12)00006-5/abstract
Written by Rutuja Adake