Endocrine System 1

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Endocrine System (1)

• Ema A. Dragoescu, M.D.
• June 10, 2008

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Endocrine System - Introduction

• Group of organs that orchestrates a state of
  metabolic equilibrium between various tissues in
  the body
• Hormones
• Feedback inhibition
• Endocrine diseases
• Underproduction / overproduction
• Mass lesion (can be nonfunctional or functional)

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Endocrine System

• Part 1
• Pituitary gland
• Thyroid gland
• Parathyroid glands

• Part 2
• Adrenal gland
• Endocrine pancreas
• Multiple endocrine neoplasia (MEN) syndromes

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Pituitary

• Base of brain (sella turcica)
• Central role in regulation of other endocrine
  organs
• Anterior pituitary secretes 6 hormones
• Posterior pituitary secretes 2 hormones
• Antidiuretic hormone (ADH), also known as
  vasopressin
• Oxytocin

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Disorders of Pituitary

• Hyperpituitarism Pituitary adenoma
• Hypopituitarism
• Ischemic injury (Sheehan syndrome)
• Surgery or radiation
• Inflammatory conditions (sarcoidosis, TB)
• Nonfunctional pituitary adenoma
• Local mass effect
• Rx abnormalities of the sella turcica
• Visual field defects
• Elevated intracranial pressure

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Anterior pituitary adenoma

• Composed of a single cell type that produces a
  single hormone
• Well-circumscribed, soft lesion
• Adenoma can be
• Functional / nonfunctional
• Isolated / associated with MEN-1 (3)
• Microadenoma (lt1.0 cm) / macroadenoma (gt1.0 cm)

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Functional Pituitary Adenomas

• Prolactinoma
• Most common
• Amenorrhea, galactorrhea, loss of libido,
  infertility
• GH-producing adenoma
• Second most common
• Stimulates secretion of hepatic IGF I
• Before epiphyses close Gigantism
• After epiphyses close Acromegaly
• ACTH-producing adenoma Cushing disease

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Gigantism

• Generalized increase in body size
• Rapid linear growth with disproportionately long
  arms and legs
• If increased GH levels persist after closure of
  epiphyses ? acromegaly

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Acromegaly

• Soft tissue and skin thickening ? coarse facial
  features
• Enlargement of visceral organs
• Enlargement of bones of face, hands, and feet
• Abnormal glucose intolerance ? diabetes mellitus

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Acromegaly

• Enlargement of the jaw
• Prognathism (difficulty with bite)
• Broadening of the lower face
• Separation of teeth
• Enlarged hands and feet with broad, sausage-like
  fingers
• Increased gloves size, shoe size

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Posterior pituitary

• ADH deficiency Diabetus insipidus
• trauma, neoplasm, inflammatory conditions,
  idiopathic
• Polyuria, thirst, polydipsia
• ADH excess syndrome of inappropriate ADH
  (SIADH)
• Ectopic ADH secretion by malignant neoplasms
• Excessive resorption of water, hyponatremia,
  cerebral edema

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Thyroid gland

• Anterior neck, below the larynx
• Secretes T4 and T3
• Essential for normal maturation and metabolism of
  all tissues
• Thyroid diseases
• Hyperthyroidism
• Hypothyroidism
• Mass lesion

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Hyperthyroidism (thyrotoxicosis)

• Elevated circulating levels of free T3 and T4
  low TSH
• Due to
• Hyperfunction of thyroid gland
• Diffuse toxic hyperplasia (Graves disease)
• Hyperfunctioning multinodular goiter
• Hyperfunctioning (toxic) adenoma
• Thyroiditis
• Extra-thyroidal source (struma ovarii,
  factitious)
• Radioactive iodine uptake

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Hypothyroidism

• High serum TSH, low free T3 and T4
• Due to
• Iodine deficiency
• Hashimoto thyroiditis
• Postablative (surgery, radiation)
• Congenital enzymatic defects
• Drugs (lithium), other substances
• Two clinical manifestations
• Cretinism (infancy, early childhood)
• Myxedema (older children, adults)

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Graves disease

• Autoimmune disorder (autoantibodies to TSH
  receptor)
• 20-40 yearsFM71
• Characterized by
• Thyrotoxicosis (diffusely enlarged and
  hyperfunctional thyroid)
• Exophthalmos
• Pretibial myxedema

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Graves Disease

• Diffuse hypertrophy and hyperplasia of follicular
  cells
• Tall, columnar, crowded
• Small papillae projecting into lumen
• Pale colloid with scalloped borders
• Lymphoid infiltrate may be present

Graves disease
Normal
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Hashimoto Thyroiditis (chronic lymphocytic
thyroiditis)

• Autoimmune destruction of thyroid gland
• Most common cause of hypothyroidism (where iodine
  is sufficient)
• 45-65 years FM10-201
• Painless enlargement of thyroid hypothyroidism
• Symmetrical, bilateral
• T3, T4low TSHhigh
• Associated with other autoimmune disorders
• Risk of developing lymphoma

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Hashimoto Thyroiditis

• Mononuclear inflammatory infiltrate
• Small lymphocytes, plasma cells, germinal centers
• Thyroid follicles are atrophic
• Hurthle (oxyphil) cells
• Fibrosis

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Other forms of thyroiditis

• Subacute granulomatous thyroiditis (de Quervain)
• Self-limited (6-8 weeks)
• h/o upper respiratory infection
• Painful thyroid, fever
• Granulomas
• Subacute lymphocytic thyroiditis (postpartum)
• Painless
• Chronic inflammation of thyroid

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Diffuse and Multinodular Goiter

• Enlargement of thyroid
• Impaired synthesis of thyroid hormones
• Euthyroid or hypothyroid
• Endemic or sporadic
• Compression of trachea, esophagus, can grow into
  thoracic cavity
• All diffuse goiters ? MNG

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Goiter versus neoplasm
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Neoplasms of the Thyroid

• Follicular adenoma
• Carcinoma
• Papillary carcinoma
• Follicular carcinoma
• Medullary carcinoma
• Anaplastic carcinoma

• Clues
• More likely to be malignant
• Solitary nodule
• Young patient
• Male patient
• h/o RT to HN
• More likely to be benign
• Hot nodules on radioactive iodine scan

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Papillary carcinoma
Follicular carcinoma
Anaplastic carcinoma
Medullary carcinoma
Anaplastic carcinoma
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Papillary Thyroid Carcinoma

• Most common (80)
• Risk factor radiation
• Papillary architecture
• Characteristic nuclear features
• Nuclear grooves
• Nuclear inclusions
• Orphan Annie nuclei

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Follicular Carcinoma

• 10-20
• Single nodule
• Follicular architecture
• Capsular and vascular invasion

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Medullary Thyroid Carcinoma

• Rare (5)
• Originates from C-cells (calcitonin)
• Amyloid stroma
• Sheets of neuroendocrine cells
• Sporadic (80)
• Familial (MEN IIa and MEN IIb)

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Thyroglossal Duct Cyst

• Remnant of embryonic thyroglossal duct
• Thyroid gland develops from the foramen cecum (at
  the base of tongue) and migrates to the anterior
  neck
• Ectopic thyroid tissue (lingual thyroid)

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Parathyroid Glands

• 4 glands
• Chief cells ? PTH
• PTH secretion is controlled by serum levels of
  free Ca
• PTH actions
• Mobilizes Ca from bones
• Increases renal reabsorption of Ca and P
  excretion
• Increases conversion of vit. D. to active form
• Increases GI absorption of Ca

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Hyperparathyroidism

• Primary
• Due to
• Adenoma (75-80)
• Hyperplasia (10-15)
• Carcinoma (lt5)
• Hypercalcemia
• Sporadic (95)
• MEN-1 and MEN-2a (5)
• Secondary
• Tertiary

Normal parathyroid
Parathyroid adenoma
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Primary Hyperparathyrodism

• High PTH, high Ca
• painful bones, renal stones, abdominal groans,
  psychic moans
• Osteoporosis, osteitis fibrosa cystica, brown
  tumor
• Renal stones
• GI constipation, peptic ulcer, pancreatitis,
  gallstones
• CNS lethargy, depression
• Muscle weakness and hypotonia

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Brown tumor of hyperparathyroidism. Large number
of osteoclast-like giant cells. It is impossible
to distinguish this tumor from other giant cell
lesions of the bone. Sharply defined, radiolucent
lesions, more frequently in the mandible.
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Hypoparathyrodism

• Caused by
• Surgical ablation
• Congenital absence
• Autoimmune
• Hypocalcemia
• Tingling, muscle spasm, tetany
• Cardiac arrhythmias
• Seizures
• Dental abnormalities small teeth with
  hypoplastic enamel, stunted roots, structural
  abnormalities in the radicular dentine

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Aspects of endocrine disease relevant to dentistry

• Recognize clinical manifestations of
• Gigantism / acromegaly
• Hyperthyrodism / hypothyroidism
• Be able to recognize goiter, thyroid nodule,
  thyroglossal duct cyst, lingual thyroid
• Brown tumor of hyperparathyroidism
• Dental abnormalities of hypoparathyroidism