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Pathomorphology · Chapter 19. Diseases of the Endocrine System

Thyroid disorders

Thyroid pathologies manifest as changes in its endocrine activity — a decrease (hypothyroidism) or an increase (hyperthyroidism). Since thyroid hormones (thyroxine and triiodothyronine) regulate the metabolism of the entire body, their imbalance causes multiple systemic disorders.

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Autoimmune failureHashimoto's goiter arises due to a defect in CD8+ lymphocytes, which leads to the attack of own cells.
Role of dietExcess thiocyanates (cabbage, turnip), calcium, and lithium can trigger hypothyroidism.
Triad of symptomsSevere hyperthyroidism always manifests with the classic triad: goiter, exophthalmos, and tachycardia.
EpidemiologyHypothyroidism occurs in women 10 times more often than in men, and in individuals over 65 years of age, the risk increases.
3 min readFor medical studentsUpdated 10.10.2026
Material prepared by WhiteCoat Pro editorial team based on platform study guidesPending instructor review

Main groups of pathologies and conditions

Morphologically, three main groups of diseases are distinguished: thyroiditis (inflammation), goiter (struma), and tumors.

Depending on the level of hormone production in the body, one of three states may be observed:

  1. Euthyroid state — the endocrine activity of the gland is unchanged.
  2. Hypothyroidism — the clinical manifestation of hormone deficiency.
  3. Hyperthyroidism (thyrotoxicosis) — the clinical manifestation of hormone excess.

Hypothyroidism: etiology and manifestations

Thyroid hormone deficiency leads to a global slowing of metabolism. The disease is classified according to the level of lesion:

  • Primary: pathology of the gland itself (aplasia, congenital disorders, iodine deficiency).
  • Secondary: pituitary lesion.
  • Tertiary: hypothalamic lesion (in encephalitis, tumors, sarcoidosis).
  • Iatrogenic: consequences of medical interventions (removal of the gland, radiation therapy).

The clinical picture covers all systems. Mucous edema of the skin develops (myxedema); it becomes dry and acquires a yellowish tint due to carotene accumulation. From the nervous system side, drowsiness, memory impairment, adynamia, and feeling cold are noted. The cardiovascular system responds with bradycardia and the development of a "myxedema heart". In the gastrointestinal tract, peristalsis slows down, achlorhydria occurs, and sometimes ascites.

Important: The development of hypothyroidism at an early age leads to irreversible intellectual changes — cretinism, as well as delayed bone growth.

Test your knowledge on the topicTasks from the "Pathological Anatomy" course bank — instant answers and explanations.

Hyperthyroidism (thyrotoxicosis)

Hormone excess sharply accelerates basal metabolism: oxygen consumption rises, body temperature increases. Activation of lipolysis and protein breakdown leads to weight loss, muscle atrophy, and fatty liver degeneration. Hyperglycemia develops.

Causes: diffuse toxic goiter, thyrotoxic adenoma, thyrotropic pituitary adenoma. Non-thyroidal hormone production is also possible, for example, in ovarian teratoma (ectopic goiter) or trophoblastic tumors.

Systemic changes:

  • Eyes: spasm of extraocular muscles, immune inflammation of the periorbital tissue (exophthalmos).
  • Heart: tachycardia, arterial hypertension, myocardial hypertrophy, and thyrotoxic cardiomyopathy.
  • Nervous system: hyperexcitability, tremor, hyperreflexia.
  • Skin: sweating, heat intolerance, pretibial myxedema, pigmentation (a consequence of relative adrenal insufficiency).
  • Reproductive sphere: in men — suppression of spermatogenesis, gynecomastia, and impotence; in women — up to amenorrhea.
  • Bones: increased excretion of calcium and phosphorus provokes osteoporosis, finger phalanges change to a "clubbing" type.

Thyroiditis

Thyroiditis is inflammation of the thyroid gland. According to its course, it is divided into three forms:

  1. Acute thyroiditis. It can be purulent (infectious — due to staphylococci or streptococci) or non-purulent (radiation). It manifests with severe pain upon swallowing, fever up to 40 °C. In case of an abscess, the fluctuation sign occurs.
  2. Subacute thyroiditis.
  3. Granulomatous (de Quervain's): has a viral etiology (influenza viruses, Coxsackie). Macrophage granulomas with giant cells form in the follicles.
  4. Lymphocytic (postpartum): proceeds asymptomatically, characterized by small focal infiltrates.
  5. Chronic lymphocytic thyroiditis (Hashimoto's goiter). An organ-specific autoimmune disease. T-helper cells interact with epithelial antigens, activating killer lymphocytes. Antibodies to thyroglobulin and thyroid peroxidase are detected in the blood. Microscopically, pronounced lymphoid-cell infiltration, follicular atrophy, and sclerosis are visible. It ends in progressive hypothyroidism.
How to memorize

To memorize the clinical triad of severe hyperthyroidism, use the "GET" rule: Goiter, Exophthalmos (bulging eyes), Tachycardia.

Class and exam questions

Why does fatty liver degeneration and rapid weight loss occur in hyperthyroidism?

Hormone excess sharply activates lipolysis and protein breakdown. Fat is mobilized from depots, which leads to weight loss and fatty infiltration of parenchymatous organs.

Why are signs of hyperthyroidism often observed in subacute thyroiditis?

The inflammatory process destroys the follicles of the gland. Thyroxine and triiodothyronine contained within them passively spill into the bloodstream, causing symptoms of thyrotoxicosis.

How can food products cause hypothyroidism?

In addition to iodine deficiency, the disease can be triggered by an excess of thiocyanates (found in cabbage, rutabaga, turnip), as well as lithium and calcium ions, which block the uptake of iodine by the gland.

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What else to study on this topic

  • Genetic predisposition to thyroiditis (HLA system antigens: DR3, DR5, Bw35)
  • Microscopic picture of early and late changes in de Quervain's subacute thyroiditis
  • Ectopic pancreatic tumors (corticotropinoma, parathyrenoma) and their hormonal activity
  • "Pancreatic cholera" syndrome in VIPoma (Werner-Morrison tumor)
  • Pathogenesis of water-electrolyte balance disorders in hyperthyroidism

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Other topics in Chapter 19: Diseases of the Endocrine System

General pathology of the endocrine systemPathology of the endocrine part of the pancreasThyroid pathologyPathology of the parathyroid glandsPituitary pathologyAdrenal pathologyThyroid cancer
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