1.

Hypothyroidism

Definition:

A condition where the thyroid gland produces insufficient thyroid hormones (T3 and T4),
leading to a slowdown of metabolic processes.

Types:

 Primary Hypothyroidism: Due to dysfunction of the thyroid gland itself.

 Secondary Hypothyroidism: Due to pituitary gland failure.

 Tertiary Hypothyroidism: Due to hypothalamic dysfunction.

 Congenital Hypothyroidism: Present at birth.

Causes:

 Autoimmune diseases (e.g., Hashimoto’s thyroiditis)

 Iodine deficiency

 Thyroid surgery or radioactive iodine therapy

 Congenital defects

 Medications (e.g., lithium, amiodarone)

Diagnosis:

 Blood tests:

o High TSH

o Low Free T4

 Thyroid antibodies test (e.g., anti-TPO) for autoimmune causes

 Thyroid ultrasound (if nodules are suspected)

Signs and Symptoms:

 Fatigue, cold intolerance

 Weight gain

 Bradycardia

 Dry skin, hair thinning

  Depression, memory issues

 Menstrual irregularities

 Constipation

Pathophysiology:

Reduced production of T3/T4 leads to decreased metabolic rate. The pituitary gland responds
by increasing TSH to stimulate the thyroid gland.

Complications:

 Myxedema coma (life-threatening)

 Goitre

 Infertility

 Depression

 Cardiovascular problems (e.g., bradycardia, high cholesterol)

Management:

 Hormone replacement therapy: Levothyroxine (T4)

 Regular monitoring: TSH and Free T4 levels

 Address underlying causes (e.g., iodine supplementation)

2. Hyperthyroidism

Definition:

A condition where the thyroid gland produces excess thyroid hormones, leading to an increased
metabolic rate.

Types:

 Graves’ disease (autoimmune)

 Toxic multinodular goitre

 Thyroiditis (inflammation)

 Toxic adenoma

Causes:
  Graves’ disease

 Excess iodine intake

 Thyroid nodules

 Certain medications (e.g., amiodarone)

Diagnosis:

 Blood tests:

o Low TSH

o High Free T4 and/or T3

 Radioactive iodine uptake test

 Thyroid scan

 Thyroid antibodies (TSI in Graves’)

Signs and Symptoms:

 Weight loss, heat intolerance

 Palpitations, tachycardia

 Tremors, anxiety

 Excessive sweating

 Diarrhea

 Menstrual disturbances

 Exophthalmos (in Graves’ disease)

Pathophysiology:

Excess T3/T4 increases the metabolic rate and stimulates various body systems. In autoimmune
cases (e.g., Graves'), antibodies stimulate TSH receptors.

Complications:

 Thyroid storm (acute, life-threatening)

 Atrial fibrillation

 Osteoporosis
  Infertility

 Eye problems (in Graves’ disease)

Management:

 Antithyroid drugs: Methimazole, propylthiouracil

 Beta-blockers: For symptom relief

 Radioactive iodine therapy

 Thyroidectomy (surgical removal)

 Eye care (for Graves' ophthalmopathy)

3. Goitre

Definition:

An abnormal enlargement of the thyroid gland, which can occur with normal, increased, or
decreased thyroid function.

Types:

 Simple (non-toxic) goitre

 Toxic goitre (associated with hyperthyroidism)

 Nodular goitre (multinodular or solitary nodule)

 Endemic goitre (due to iodine deficiency)

Causes:

 Iodine deficiency

 Hashimoto’s thyroiditis

 Graves’ disease

 Thyroid nodules or cysts

 Certain drugs (e.g., lithium)

 Hereditary factors

Diagnosis:
  Thyroid function tests: TSH, Free T4/T3

 Thyroid ultrasound

 Fine needle aspiration (if nodules present)

 Radioactive iodine uptake scan

Signs and Symptoms:

 Visible neck swelling

 Tight feeling in the throat

 Coughing or hoarseness

 Difficulty swallowing or breathing (if large)

 Symptoms of hypo- or hyperthyroidism if functional

Pathophysiology:

Thyroid gland enlargement occurs due to chronic stimulation (e.g., by TSH) or autoimmune
reactions, depending on the underlying cause.

Complications:

 Compression of trachea/esophagus

 Cosmetic issues

 Functional disturbances (hypo/hyperthyroidism)

 Malignancy (rarely)

Management:

 Observation (if small and non-symptomatic)

 Iodine supplementation (for deficiency)

 Thyroid hormone therapy

 Surgery (for large, compressive, or suspicious goitres)

 Radioactive iodine (in toxic goitre)

Comparison Summary Table:

Aspect Hypothyroidism Hyperthyroidism Goitre

Hormone Level ↓ T3/T4, ↑ TSH ↑ T3/T4, ↓ TSH Normal/↑/↓ (varies)

Metabolic Rate Decreased Increased Variable

Common Cause Hashimoto’s Graves’ disease Iodine deficiency

Symptoms Fatigue, cold, slow Weight loss, heat, fast Neck swelling, ± symptoms

Treatment Levothyroxine Antithyroid meds, RAI Observation, surgery, iodine