Causes of Goitre Overview
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Questions and Answers

Endemic goitre occurs when more than 20% of a community has goitre.

False

What is a common cause of congenital goitre?

  • Genetic factors
  • Excess iodine in the diet
  • Dyshormonogenesis due to enzyme deficiency (correct)
  • Thyroid cancer

    • Excess iodine intake can lead to _______ goitre.

    iodine

    What is the primary reason for acquired goitre in dietary cases?

    <p>Iodine deficiency</p> Signup and view all the answers

    Match the type of goitre with its description:

    <p>Endemic goitre = More than 10% of the community affected Sporadic goitre = Occurs in a smaller number of people Iodine goitre = Caused by excessive intake of iodine Dietary goitre = Result of iodine deficiency in diet</p> Signup and view all the answers

    Dyshormonogenesis can be a cause of sporadic goitre.

    <p>True</p> Signup and view all the answers

    Which of the following factors can lead to iatrogenic goitre?

    <p>Excess iodine intake over time</p> Signup and view all the answers

    In which age group do sporadic goitres typically occur?

    <p>20-39 years</p> Signup and view all the answers

    Physiological goitre may occur during puberty, menstruation, and pregnancy.

    <p>True</p> Signup and view all the answers

    What condition can result from the persistent use of large doses of iodine in patients with long-standing nodular goitre?

    <p>Jod-Basedow Thyrotoxicosis</p> Signup and view all the answers

    What autoimmune condition is characterized by chronic thyroiditis?

    <p>Hashimoto's thyroiditis</p> Signup and view all the answers

    The condition caused by mistakenly ingesting exogenous thyroid hormone is called __________.

    <p>thyrotoxicosis factitia</p> Signup and view all the answers

    Match the following types of thyroiditis with their descriptions:

    <p>Acute Suppurative Thyroiditis = Bacterial infection Granulomatous Thyroiditis = Viral origin Riedel's Thyroiditis = Fibrous and invasive Hashimoto's Thyroiditis = Autoimmune origin</p> Signup and view all the answers

    Which of the following substances can inhibit the trapping and concentration of iodine?

    <p>All of the above</p> Signup and view all the answers

    Simple goitre is characterized as a non-toxic and malignant condition.

    <p>False</p> Signup and view all the answers

    Excessive iodine intake can block the binding of iodine to __________ residues of thyroglobulin.

    <p>tyrosine</p> Signup and view all the answers

    What characterizes an ovarian teratoma that includes thyroid tissue?

    <p>More than 50% thyroid tissue</p> Signup and view all the answers

    What are the two types of goitre mentioned?

    <p>Parenchymatous goitre and colloid goitre.</p> Signup and view all the answers

    Colloid goitre is caused solely by a persistent increase in TSH stimulation.

    <p>False</p> Signup and view all the answers

    Which condition is described as congenital deafness along with neonatal euthyroid goitre?

    <p>Pendred's syndrome</p> Signup and view all the answers

    Toxic goitre is associated with _____ due to the stimulating effect of TSH.

    <p>thyrotoxicosis</p> Signup and view all the answers

    A multinodular goitre results from a consistent increase in TSH stimulation.

    <p>False</p> Signup and view all the answers

    The antibodies that cause hypermetabolism in toxic goitre are known as _____ and are produced by lymphocytes.

    <p>Thyroid Stimulating Immunoglobulin (TSI)</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>TSH = Hormone that stimulates the thyroid gland T3 = Active thyroid hormone that can increase in quantity in thyrotoxicosis Goitre = Enlargement of the thyroid gland Thyrotoxicosis = Condition of excess thyroid hormones</p> Signup and view all the answers

    What is the condition caused by infiltration of retro-orbital tissues by lymphocytes, resulting in protrusion of the eyeball?

    <p>Exophthalmos</p> Signup and view all the answers

    Graves disease is characterized by primary thyrotoxicosis due to a previously healthy gland.

    <p>True</p> Signup and view all the answers

    The clinical state characterized by hypermetabolism due to excessive thyroid hormones is known as _______.

    <p>hyperthyroidism</p> Signup and view all the answers

    What substance is believed to cause thyroid autoimmunity due to shared auto-antigens between the thyroid and extraocular muscles?

    <p>Exophthalmos Producing Substance (EPS)</p> Signup and view all the answers

    Match the thyroid disorders with their descriptions:

    <p>Graves' Disease = Primary thyrotoxicosis causing diffuse goiter Hashimoto’s Disease = Autoimmune hypothyroidism leading to thyroid destruction Plummer’s Disease = Secondary thyrotoxicosis associated with a diseased gland DeQuervain's Thyroiditis = Painful inflammation of the thyroid</p> Signup and view all the answers

    Eye signs are typical in secondary thyrotoxicosis.

    <p>False</p> Signup and view all the answers

    Which of the following is a feature of pretibial myxoedema?

    <p>Irregular thickening of the skin</p> Signup and view all the answers

    Name one of the features characteristic of primary thyrotoxicosis.

    <p>Diffuse goiter, eye signs, pretibial myxoedema, or raised T3/T4 levels</p> Signup and view all the answers

    Which of the following types of thyroid cancer is most common?

    <p>Papillary carcinoma</p> Signup and view all the answers

    De Quervain's disease is a benign condition of the thyroid.

    <p>False</p> Signup and view all the answers

    What are psammoma bodies commonly found in?

    <p>Papillary tumors</p> Signup and view all the answers

    Thyroid cancers that arise from parafollicular C cells are known as ________ carcinoma.

    <p>medullary</p> Signup and view all the answers

    Match the thyroid cancer types with their features:

    <p>Papillary carcinoma = Metastasizes via lymphatics and contains psammoma bodies Follicular carcinoma = Well encapsulated and metastasizes via vascular route Medullary carcinoma = Arises from parafollicular C cells and secretes calcitonin Anaplastic carcinoma = Rapidly growing and radiosensitive</p> Signup and view all the answers

    Follicular carcinoma is easier to diagnose through FNAC than papillary carcinoma.

    <p>False</p> Signup and view all the answers

    Which of the following is NOT a feature of Anaplastic thyroid carcinoma?

    <p>Well-encapsulated structure</p> Signup and view all the answers

    Name one clinical symptom associated with thyroid cancers.

    <p>Hoarseness</p> Signup and view all the answers

    Study Notes

    Causes of Goitre

    • Goitre is an enlargement of the thyroid gland and requires a threefold increase in its size to be visible.
    • Goitre can be congenital or acquired.
    • Congenital goitre results from dyshormonogenesis due to enzyme deficiencies.
      • Reduced conversion of organic iodine in the diet to inorganic iodine in the blood.
      • Insufficient inorganic iodine absorption in the gut.
      • Deficiency of enzymes involved in oxidizing iodine, coupling iodine and tyrosine to MIT/DIT, or binding these molecules to thyroglobulin and releasing them into the bloodstream.
    • Acquired goitre can arise from dietary, iatrogenic, physiological, inflammatory, neoplastic, toxic, or neonatal causes
      • Dietary: Deficiency of iodine in food and water, as in mountainous regions.
        • Mountaneous regions with plenty of granite tend to have high calcium content in water, which has goitrogenic effects.
        • Cassava contains cyanogenic glucosides that produce thyocyanates which inhibit iodine uptake by the thyroid.
      • Iatrogenic:
        • Excessive iodine intake: Can cause acute block of iodine binding to tyrosine residues in thyroglobulin, leading to "iodine goitre" or Wolff-Choikoff block. This can occur during prolonged use of iodine-containing preparations.
        • In patients with long-standing nodular goitre, persistent use of large doses of iodine to shrink tumors can result in thyrotoxicosis, called Jod-Basedow thyrotoxicosis.
        • Thyrotoxicosis factitia (alimentary thyrotoxicosis or exogenous thyrotoxicosis): This is thyrotoxicosis caused by accidental ingestion of exogenous thyroid hormone (e.g., Levothyroxine used in replacement therapy or tri-iodothyronine), or Munchausen syndrome.
      • Physiological: Goitre can arise from increased need for thyroid hormones during puberty, menstruation, pregnancy, and lactation.
      • Inflammation/Thyroiditis:
        • Acute (suppurative) thyroiditis (bacterial)
        • Sub-acute granulomatous thyroiditis, giant cell thyroiditis (de Quervain's, nonsuppurative thyroiditis)
        • Chronic thyroiditis:
          • Hashimoto's (autoimmune) thyroiditis: Autoimmune origin, with hyperthyroidism in the acute phase and hypothyroidism in the chronic phase.
          • Riedel's thyroiditis (ligneous thyroiditis): Fibrosed, hard, and invasive fibrous thyroiditis.
      • Neoplasia (Benign and Malignant):
        • Benign: Adenoma (follicular, papillary, atypical), teratomas.
        • Malignant: Differentiated (papillary, follicular, medullary), undifferentiated (anaplastic), squamous cell, others (lymphomas, sarcomas, teratomas, metastatic deposits).
      • Toxicity:
        • Simple goitre: Non-toxic, non-hypothyroid, and non-malignant goitre.
        • Toxic goitre: Goitre associated with thyrotoxicosis.
          • Thyrotoxicosis: Caused by either TSH stimulation leading to excess T3 and T4 or by TSI stimulation, which also produces excess hormones but does not correlate with eye symptoms or pretibial myxoedema.
      • Neonatal goitre: May present as neonatal thyrotoxicosis in cases of molar pregnancy, struma ovarii (ovarian teratoma with over 50% thyroid tissue), or Pendred's syndrome (congenital deafness with neonatal euthyroid goitre).

    Histology of Goitre

    • Parenchymatous (Diffuse) goitre: Felt like the body of an orange. Occurs with hypertrophy & hyperplasia of the parenchyma due to persistent TSH stimulation.
    • Colloid goitre: Occurs with increased production of colloid within the thyroid follicle.
    • Multinodular goitre: Felt like the body of a corn hub. Occurs with irregular production of colloid due to waxing and waning TSH.

    Clinical Features of Goitre

    • Goitre, whether parenchymatous or colloidal, may be described as diffuse goitre (uniformly enlarged) or nodular (stimulated by TSH).
    • Simple (non-toxic) goitres: Simple diffuse goitre, simple nodular goitre.
    • Toxic goitres: Toxic diffuse goitre, toxic multinodular goitre, toxic nodule in a goitre.
    • Natural history of simple goitre:
      • Diffuse hyperplasia (colloid goitre)
      • Nodular (waxing and waning of TSH stimulation)
      • May become bigger with potential pressure symptoms (hoarseness, dyspnoea, dysphagia), cosmetic concerns, fibrosis, calcification, cystic changes, haemorrhage.
      • May become toxic, especially nodular goitre.
      • Infection and malignancy are possible complications.

    Toxic Goitre

    • Toxic goitre is goitre associated with thyrotoxicosis.
    • Thyrotoxicosis is a clinical state of hypermetabolism.
    • Thyrotoxicosis can be primary (in a previously healthy gland) or secondary (in a previously diseased gland).
    • Features of toxicity: Hypermetabolism (anxiety, irritability, heat intolerance, nervousness, tremulousness, emotional instability, sleeping pulse, tachycardia, heart failure). The hypermetabolism is triggered by an autoimmune protein called Thyroid Stimulating Immunoglobulin (TSI).
    • Eye signs: TSI can infiltrate retro-orbital tissues with lymphocytes leading to proptosis (bulging eyes).
    • Exophthalmos: Spasms of the eyelids, presenting as lid lag, lid retraction, and staring gaze. Caused by an exophthalmos-producing substance (EPS), which may be non-infiltrative and mild or infiltrative and malignant.
    • Pretibial myxoedema: Mucin-like substance infiltrates pretibial skin and the dorsum of the foot, causing irregular thickening of the skin, coarse hair, clubbing of fingers, and toes - thyroid acropachy.

    Graves Disease

    • Graves disease is a type of primary hyperthyroidism (toxicity in a previously healthy gland):
      • Hyperplastic goitre (diffuse goitre)
      • Thyrotoxicosis
      • Exophthalmos
      • Pretibial myxoedema.

    Plummer's Disease

    • Plummer's disease is secondary hyperthyroidism or thyrotoxicosis in a previously diseased gland.
    • Includes: Simple multinodular goitre, toxic multinodular goitre, solitary nodule, toxic nodule/adenoma, Hashimoto's disease, De Quervain's thyroiditis, malignant thyroid.
    • Natural history:
      • May become bigger, bleed, cause retrosternal crowding, become infected, become malignant, or become toxic.

    Hypothyroidism

    • A clinical state of hypometabolism caused by decreased production of the thyroid hormones T3 and T4.

    Thyroid Neoplasms

    • Benign: Adenoma, Teratomas.
    • Malignant: Papillary (most common), Follicular, Medullary, Anaplastic, Hurtle cell (from follicular cells), Squamous cell, Lymphomas, Sarcomas, Teratomas, Metastatic deposits.

    Papillary Thyroid Tumours

    • Most common, slow growing, metastasise via lymphatics, usually result from radiation therapy, occur between ages 30-40, more common in females, contain psammoma bodies.

    Follicular Thyroid Tumours

    • Metastasise via vascular route, well encapsulated, difficult to diagnose via FNAC due to difficult tissue acquisition.

    Medullary Thyroid Carcinoma

    • Arises from parafollicular (C) cells and are neurocristopathies (APUDomas).
    • May be sporadic or endemic.
    • Affects only one lobe.
    • May present as MEN IIa, MEN IIb, or non-MEN familial (MCT).
    • Secretes serotonin, prostaglandin, and calcitonin. Spread via both lymphatics and blood vessels. More common in females.

    Hurtle Cell Thyroid Cancer

    • Arise from follicular cells, spreads via lymphatic and then blood route.

    Anaplastic Thyroid Cancers

    • 75% from previously differentiated tumours, especially follicular.
    • More common in females.
    • Radiosensitive.

    Clinical Features Of Thyroid Cancers

    • Sudden and rapid enlargement of the thyroid gland.
    • Recent pain in goitre.
    • Dyspnoea.
    • Hoarseness.
    • Fixity and dysphagia.
    • Horner's syndrome (ptosis, miosis, anhidrosis).
    • Maleness.
    • Secondaries to the bone.

    Investigations for the Thyroid

    • Thyroid function tests (T3, T4, TSH).
    • X-rays: Neck (for tracheal position), thoracic inlet.
    • CT scan: Neck, chest, thoracic inlet.
    • USG, MRI.
    • Direct/indirect laryngoscopy.
    • FNAC.

    Treatment of Thyrotoxicosis

    • Medications: Antithyroid drugs (methimazole or PTU), radioactive iodine therapy, surgery.
      • Antithyroid drugs: Inhibit thyroid hormone production, with short-term use for many individuals but potential for long-term side effects.
      • Radioactive iodine therapy: Destroys thyroid cells, causing thyroid damage and a potential risk of hypothyroidism.
      • Surgery: Removal of all or part of the thyroid gland, with potential postoperative complications and hypothyroidism.

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    Description

    This quiz delves into the causes of goitre, including both congenital and acquired factors. It describes how dietary deficiencies, particularly iodine, along with various physiological and environmental influences, contribute to the enlargement of the thyroid gland. Explore the intricacies of goitre development and its underlying mechanisms.

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