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Endo > SM_175b: Hypothalamus-Pituitary Pathophysiology > Flashcards

SM_175b: Hypothalamus-Pituitary Pathophysiology Flashcards

1
Q

Congenital malformations related to ____ can lead to hypothalamic dysfunction

A

Congenital malformations related to hypothalamic dysfunction can lead to hypothalamic dysfunction

  • Other etiologies: hydrocephalus, tumors, trauma, infiltrative disease, inflammation / infection
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2
Q

Septo-optic dysplasia involves mutations in ____, ____, ____, or ____ and can lead to ____

A

Septo-optic dysplasia involves mutations in HESX1, SOX2, SOX3, or OTX2 and can lead to hypothalamic dysfunction

  • Absent septum pellucidum, agenesis of corpus callosum, optic nerve dysplasia, hypothalamic developmental dysfunction, hypopituitarism
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3
Q

Craniopharyngiomas cause varying degrees of ____, ____, and ____

A

Craniopharyngiomas cause varying degrees of hypopituitarism, hyperprolactinemia, and diabetes insipidus

  • Cysts lined with squamous epithelium and contain serous or oily fluid
  • Nodular, lobular well-demarcated cystic mass often with rim enhancement on MRI
  • Predominantly suprasellar with intrasellar component
  • Often cause headaches and visual field defects and may cause hydrocephalus
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4
Q

Describe sellar masses

A

Sellar masses

  • Pituitary adenomas
  • Cell rest tumors
  • Benign lesions
  • Metastatic tumors
  • Aneurysms
  • Primitive germ cell tumors
  • Gliomas
  • Granulomatous lesions
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5
Q

Describe differential diagnosis of thickened hypothalamic-pituitary stalk

A

Thickened hypothalamic-pituitary stalk DDx

  • Langerhans cells histiocytosis (histiocytosis X)
  • Sarcoidosis
  • Dysgerminoma
  • Infundibulohypophysitis
  • Metastasis
  • Tuberculosis
  • Lymphoma
  • Infundibuloma
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6
Q

Langerhans cell histiocytosis presents in ___ with ____

A

Langerhans cell histiocytosis presents in middle age with osteolytic lesions especially in jaw

  • May be pulmonary interstitial disease: get DLCO
  • Treat with alkylating agents, focal irradiation, vinca alkaloids
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7
Q

Sarcoidosis involves ____ and ____

A

Sarcoidosis involves CSF pleiocytosis and increased ACF levels

  • May be isolated to CNS
  • Treat with steroids
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8
Q

Dysgerminoma usually produces ____ and is ____

A

Dysgerminoma usually produces hCG and is very radiosensitive

  • Measure hCG in CSF
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9
Q

___ tuberculosis leads to progressive dysfunction

A

Hypothalamic tuberculosis leads to progressive dysfunction

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10
Q

____ and ____ can lead to hypothalamic dysfunction

A

TBI and aneurysms can lead to hypothalamic dysfunction

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11
Q

Radiation can reduce levels of ____ including ____, ____, ____, and ____

A

Radiation can reduce levels of hypothalamic hormones including TSH, ACTH, LH / FSH, and GH

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12
Q

Hypothalamic disease manifests as ____, ____, ____ and ____

A

Hypothalamic disease manifests as hypopituitarism, disordered vasopressin regulation, hyperprolactinemia, and other

  • Midline structural defects occur if hypopituitarism is due to transcription factor mutation
  • Hyperprolactinemia is failure of dopamine to reach pituitary
  • Food intake and temp regulation difficulties
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13
Q

____ causes congenital hypogonadotropic hypogonadism and is associated with ____

A

Kallmann’s syndrome causes congenital hypogonadotropic hypogonadism and is associated with anosmia

  • Mutation in gene for protein that facilitates migration of GnRH and olfactory neurons from olfactory placode to anterior septal region of hypothalamus (GnRH) and olfactoty bulbs (olfactory neurons)
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14
Q

Acquired hypogonadotropic hypogonadism may be caused by ____, ____, and ____ and is usually ____

A

Acquired hypogonadotropic hypogonadism may be caused by stress / illness, weight loss, and increased exercise and is usually functional and reversible

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15
Q

Precocious puberty is ____ caused by ____

A

Precocious puberty is early puberty (< 8 in girls, < 10 in boys) caused by early gonadotropin secretion

  • Rarely: hamartoma secreting GnRH, dysgerminoma secreting hCG
  • Central (hypothalamic) vs peripheral (gonad, adrenal)
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16
Q

Hyperprolactinemia is usually caused by ____ but can also be caused by ____

A

Hyperprolactinemia is usually caused by prolactin-secreting pituitary adenomas but can also be caused by decreased dopamine getting to normal lactrotrph cells to inhibit prolactin secretion

  • Hypothalamic tumors or infiltrative disease
  • Medications which block dopamine generation or dopamine receptor: antipsychotics, verapamil, metoclopramide
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17
Q

Integration of signals in ____ cause increase in food intake

A

Integration of signals in lateral hypothalamus cause increase in food intake

  • Damage to this area causes lack of appetite and weight loss
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18
Q

Feedback signals in ____ cause decrease in food intake

A

Feedback signals in ventromedial hypothalamus cause decrease in food intake

  • Damage to this area causes obesity
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19
Q

Anorexia is associated with by hormonal abnormalities including ____, ____, and ____

A

Anorexia is associated with by hormonal abnormalities including hypogonadotropic hypogonadism (amenorrhea), early satiety, and temperature dysregulation (hypothermia)

  • Hormonal abnormalities reversible with weight gain
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20
Q

Hypopituitarism can be caused by ____

A

Hypopituitarism can be caused by congenital defects

  • Isolated gonadotropin deficiency: GnRH deficiency (Kallmann’s) ± anosmia, gene mutations in gonadotropins or GnRH receptors
  • Isolated growth hormone deficiency: GH gene mutations, gene mutations in GHRH and GH receptors
  • Isolated ACTH and TSH deficiencies: gene mutations, receptor gene mutations
  • Multiple hormone deficiencies: Pit1 and Prop1 transcription factor gene mutations
  • Embryopathies: congenital midline defects, gene mutations in various transcription factors
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21
Q

Acquired defects causing hypopituitarism include ____, ____, ____, and ____

A

Acquired defects causing hypopituitarism include tumors, apoplexy / infarction / hemorrhage, empty sella syndrome, and hypophysitis

  • Tumors: pituitary, hypothalamic
  • Apoplexy / infarction / hemorrhage: Sheehan’s syndrome
  • Empty sella syndrome
  • Hypophysitis: usually associated with pregnancy
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22
Q

Dwarfism of Sindh is a ____

A

Dwarfism of Sindh is a genetic syndrome of GHRH receptor mutation

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23
Q

Pituitary transcription factors including ____, ____, ____, and ____ may be mutated

A

Pituitary transcription factors including Pit-1, PROP-1, HESX1, and others may be mutated

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24
Q

Describe mass effects of sellar lesions

A

Sellar lesion mass effects

  • Headache
  • Visual field defects
  • Cranial nerve palsies
  • Hypopituitarism
  • Diabetes insipidus
  • Rare effects: temperature dysregulation, dysregulation of food intake
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25
Q

Describe the order to loss of hormones after pituitary injuries

A

Loss of hormones after pituitary injuries

  1. GH
  2. LH / FSH
  3. ACTH / TSH
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26
Q

Describe symptoms and signs of pituitary apoplexy

A

Pituitary apoplexy

  • Headache
  • Altered consciousness
  • Visual symptoms: visual field defects, CN palsies (III, IV, V1, V2, VI)
  • Stiff neck
  • Fever
  • Nausea and vomiting
  • Hypotension
  • Hypopituitarism common, SIADH/DI rare
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27
Q

Sheehan’s syndrome is ____

A

Sheehan’s syndrome is pituitary necrosis occurring within a few hours of delivery and generally associated with obstetric hemorrhage

  • Hypotension thought to cause occlusive vasospasm resulting in ischemic necrosis of pituitary
  • Acute within 30 days of delivery, have < 10% of tissue left: hypotension, tachycardia, failure to lactate
  • Chronic: presents months to years later with varying degrees of hypopituitarism
  • May have partial to complete diabetes insipidus
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28
Q

Empty sella syndrome commonly presents with ____

A

Empty sella syndrome commonly presents with hypopituitarism

  • Primary or secondary
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29
Q

Describe pituitary hormone deficiencies

A

Pituitary hormone deficiencies

  • Prolactin
  • Growth hormone
  • Gonadotropins (LH and FSH)
  • TSH
  • ACTH
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30
Q

Hyporpolactinemia is associated with ____ and ____

A

Hyporpolactinemia is associated with failure of postpartum lactation and loss of other hormones

  • Sheehan’s syndrome: pituitary infarction in association with peripartum obstetric hemorrhage
  • Lymphocytic hypophysitis: inflammatory destruction of pituitary often with ACTH loss
  • Other mass lesions of the sella
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31
Q

____ may present with increased fat mass, decreased muscle mass, decreased energy, and poor quality of life

A

Adult GH deficiency syndrome may present with increased fat mass, decreased muscle mass, decreased energy, and poor quality of life

32
Q

Common etiologies of childhood GH deficiency are ____, ____, and ____

A

Common etiologies of childhood GH deficiency are idiopathic, organic, and septo-optic dysplasia

33
Q

Insulin induced hypoglycemia causes _____ GH release

A

Insulin induced hypoglycemia causes increased GH release

(inverse)

34
Q

Describe testing and treatment for GH deficiency

A

GH deficiency testing

  • ITT, Arg / GHRH, Arg / L-dopa, Arginine, L-dopa
  • IGF-1 levels not useful
  • Treatment: starting dose of 150-300 ug/day, usual final dose needed 5-10 ug/kg/dat, want IGF-1 levels in middle of normal range
35
Q

Growth hormone insensitivity syndrome (Laron’s syndrome) results from a ____ causing ____

A

Growth hormone insensitivity syndrome (Laron’s syndrome) results from a defective GH receptor causing an inability to generate IGF-1

  • Recessive gene
  • IGF lower than in GH deficiency
36
Q

Gonadotropin deficiency has ____ and ____ manifestations

A

Gonadotropin deficiency has prepubertal and postpubertal manifestations

  • Prepubertal: failure to go through puberty
  • Postpubertal: lack of libido / impotence / infertilitty / decreased hair growth / osteoporosis in men, lack of libido / oligo/amenorrhea / infertility / osteoporosis in women
37
Q

Describe diagnosis and treatment of gonadotropin deficiency

A

Gonadotropin deficiency

  • Diagnosis: measure LH, FSH, estradiol, testosterone
  • Common: mass lesions, reversible (exercise, weight), idiopathic
  • Treatment: testosterone for men, cyclic estrogen / progesterone for women, stimulate gonad with gonadotropins for fertility
38
Q

TSH deficiency manifests as ____

A

TSH deficiency manifests as secondary hypothyroidism

39
Q

TSH deficiency diagnosis involves ____ and treatment involves ____

A

TSH deficiency diagnosis involves low thyroid hormones and lack of elevation of TSH and treatment involves l-thyroxine

40
Q

ACTH deficiency manifests as ___

A

ACTH deficiency manifests as secondary hypoadrenalism

  • Lose cortisol and adrenal androgens
  • Aldosterone relatively normal
  • Na+ low from lack of cortisol and K+ normal because aldosterone is normal
41
Q

____ deficiency is the most important homrone deficiency due to an inability to respond to ____ which may result in death

A

ACTH deficiency is the most important homrone deficiency due to an inability to respond to stress which may result in death

42
Q

ACTH deficiency diagnosis involves ____ and treatment involves ____

A

ACTH deficiency diagnosis involves low cortisol and ACTH and treatment involves replacing hydrocortisone first

43
Q

Pituitary tumors may manifest as ____ or ____

A

Pituitary tumors may manifest as mass effects of oversecretion syndromes

  • Mass effects: headache, visual field defects, CN palsies, and hypopituitarism
  • PRL: prolactinoma
  • GH: acromegaly
  • ACTH: Cushing’s disease
  • TSH: hyperthyroidism
  • LH / FSH: none
  • Nonfunctioning
44
Q

Microadenoma is ____ in greatest dimension

A

Microadenoma is < 1 cm in greatest dimension

45
Q

Macroadenoma is ___ in greatest dimension, can be ____, and has ____ extension

A

Macroadenoma is > 1 cm in greatest dimension, can be invasive or noninvasive, and has extrasellar extension

46
Q

Inherited forms of pituitary adenomas include ____, ____, and ____

A

Inherited forms of pituitary adenomas include familial isolated pituitary adenoma (FIPA) syndrome, multiple endocrine neoplasia (MEN) type 1, and Carney complex

  • FUPA: germline mutation in gene for aryl hydrocarbon receptor-interacting protein (tumor suppressor)
  • MEN type 1: mutation in menin (tumor suppressor)
  • Carney complex: mutation in type 1A subunit of Protein Kinase A (PRKAR1A)
47
Q

Describe principles of evaluation for pituitary adenomas

A

Pituitary adenomas principles of evaluation

  • Establish that a hormone excess syndrome exists: exclude other potential causes, demonstrate nonsuppressibility of homrone oversecretion
  • Image pituitary / hypothalamic area with MR or CT: may need visual field testing
  • Evaluate for other mass effects if macroadenoma: hypopituitarism
48
Q

Pituitary adenoma treatment includes ____, ____, and ____

A

Pituitary adenoma treatment includes surgery, irradiation, and medical therapy

49
Q

Describe regulation of prolactin secretion

A

Prolactin secretion regulation

  1. Hypothalamus secretes TRH and VIP
  2. Pituitary secretes prolactin
  3. Acts on breast
  4. Positive feedback on hypothalamus via spinal afferent pathways (suckling)
50
Q

Describe clinical manifestations of hyperprolactinemia

A

Hyperprolactinemia clinical manifestations

  • Men: decreased libido, erectile dysfunction, gynecomastia, galactorrhea, infertility, osteopenia
  • Women: oligo-amenorrhea / infertility, galactorrhea, estrogen deficiency, osteopenia, diminished lipido / dyspareunia
  • Acne / hirsutism
51
Q

____ may result from hyperprolactinemia

A

Hypogonadism may result from hyperprolactinemia

52
Q

____ is a ____ that is most useful for the treatment of prolactinomas

A

Cabergoline is a dopamine agonist that is most useful for the treatment of prolactinomas

  • Efficacy in normalizing prolactin levels: 80-90%
  • Efficacy in shrinking tumors
  • Can also use bromocriptine
53
Q

Prolactin levels and pituitary size ___ during normal pregnancy due to ___

A

Prolactin levels and pituitary size increase during normal pregnancy due to lactotroph hyperplasia

  • Concerns in patients with prolactinomas: dopamine agonist use safe, macroadenomas increase, nursing does not increase tumo size but cannot nurse while taking dopamine agonists that suppress prolactin
54
Q

Describe growth hormone regulation

A

Growth hormone regulation

  1. Hypothalamus secretes GHRH
  2. Pituitary secretes GH
  3. Liver and bones secrete IGF-1 and negatively feedback on pituitary and hypothalamus
55
Q

____ is involved in the pathogenesis of acromegaly

A

IGF-1 is involved in the pathogenesis of acromegaly

56
Q

Acromegaly involves a ____ due to a ____ mutation

A

Acromegaly involves a constitutively activated adenyl cyclase due to a GSP mutation

  • Mutations found in alpha sunit of guanine nucleotide binding stimultory regulatory protein (Gs) that couples the GHRH receptor to adenyl cyclase in pituitary GH-secreting adenomas in about 40% of patients with acromegaly
  • Mutations result in unregulated, high activity of adenyl cyclase and secretion of GH and cell proliferation
  • Tumors with mutation are not significantly different from those without mutations with respect to size, GH levels, invasiveness, and curability
57
Q

Acromegaly involves many ____ and decreases ____

A

Acromegaly involves many comorbidities and decreases survival

58
Q

Diagnostic testing for acromegaly involves ____, ____, and ____

A

Diagnostic testing for acromegaly involves

  • Inability to suppress GH levels during an oral glucose tolerance test
  • Elevated serum IGF-1 level (age matched)
  • MRI to identify location and size of tumor (60% macroadenomas)
59
Q

Acromegaly treatment involves ____ or ____

A

Acromegaly treatment involves surgery and medical therapy

  • Microadenomas easier to cure than macroadenomas
  • Dopamine agonists: cabergoline
  • Somatostatin analogs: octreotide, lantreotide (better)
  • GH receptor antagonist: pegvisomant
60
Q

Describe the mechanism of hGH binding and signal transduction

A

hGH binding and signal transduction mechanism

  1. hGH has two binding sites, each of which bind identical cell surface receptor
  2. Both sites bind, dimerizing the receptor
  3. Signal transduction occurs
  4. IGF-1 produced
61
Q

Describe action of Pegvisomant (GH receptor antagonist)

A

Pegvisomant (GH receptor antagonist)

  1. Site-2 binding disrupted by substituting an amino acid with a long side-chain in G120 position
  2. Site-1 binding to GH receptor enhanced, preventing hGH from binding to receptor, greately increasing potency of GH antagonist
  3. Functional dimerization prevented
  4. Signal transduction does not occur
  5. IGF-1 production does not occur
62
Q

Cushing’s syndrome is ____

A

Cushing’s syndrome is hypercortisolism

63
Q

TSH producing pituitary adenoma causes ____ and may be treated with ____ or ____

A

TSH producing pituitary adenoma causes hyperthyroidism and may be treated with ablative treatment or octreotide / lantreotide

64
Q

Gonadotroph adenomas occur in ____ who are ____, have a ____, and have ____

A

Gonadotroph adenomas occur in males who are > 40 years of age, have a normal past history of gonadal function, and have enormous pituitary size

  • Visual field defects, hypopituitarism and hypogonadism, hyperprolactinemia, and extrasellar extension on CT or MIR
  • Can make isolated alpha and beta subunits or intact LH or FSH
65
Q

Clinically nonfunctioning pituitary adenomas include ____ and ____

A

Clinically nonfunctioning pituitary adenomas include asymptomatic and symptomatic

  • Asymptomatic: present as incidental finding on MRI that has been done for other reason
  • Symptomatic: mass effects (visual field defects, headaches, hypopituitarism), primary therapy is surgery
66
Q

Indications for radiotherapy for pituitary adenomas include ____, ____, and ____

A

Indications for radiotherapy for pituitary adenomas include prolactinomas, GH / ACTH / TSH secreting pituitary adenomas, and clinically nonfunctioning adenomas

  • Medical therapies: prolactinoma, acromegaly, Cushing’s, TSH secreting tumors
67
Q

Diabetes insipidus is ____ and presents as ____ and ____

A

Diabetes insipidus is deficiency of vasopressin secretion or action and presents as polyuria and polydipsia

  • Polyuria: large volume of dilute urine as a result of failure of vasopressin to act on the kidney to promote water resorption
  • Polydipsia: increased thirst and/or fluid intake as a result of the rise in serum osmolality brought on by the excessive urinary losses of water
68
Q

Central diabetes insipidus is caused by ____

A

Central diabetes insipidus is caused by primary deficiency

  • Destruction of neurohypophysis
  • Increased degradation of placenta
69
Q

Nephrogenic diabetes insipidus is ____ caused by ____

A

Nephrogenic diabetes insipidus is resistance to antidiuretic action of AVP caused by defective V2 receptor signaling

70
Q

____ can treat central diabetes insipidus

A

DDAVP can treat central diabetes insipidus

  • Urine output decreases to normal
  • Thirst and fluid intake also decrease rapidly commensurate with urine output
  • Water retention and resultant fall in serum Na+ is minimal
71
Q

Excessive vasopressin secretion / action may ____ and ____, but these have no effect if ____ and ____ are ____

A

Excessive vasopressin secretion / action may raise urine osmolality and reduce urine output, but these have no other effect if thirst and water intake are reduced proportionately as they normally area

72
Q

Normal or increased water intake in the setting of increases vasopressin secretion / action will result in ____ and ____

A

Normal or increased water intake in the setting of increases vasopressin secretion / action will result in hyponatremia and symptoms of water intoxication (nausea, headache, confusion, death)

73
Q

Primary cause of excess vasopressin may lead to ____, ____, or ____ hyponatremia

A

Primary cause of excess vasopressin may lead to SIADH, ectopic, or eutopic hyponatremia

  • SIADH: no known stimulus to ADH secretion
  • Ectopic: tumors making vasopressin
  • Eutopic (neurohypophysis): strokes, head trauma, and other acute illnesses
74
Q

Secondarily excess vasopressin may cause ____ hyponatremia

A

Secondarily excess vasopressin may cause multiple types of hyponatremia

  • Secondary: known non-osmotic stimulus
75
Q

Describe treatment of hyponatremia

A

Hyponatremia treatment

  • Decreased effective volume -> restrict water intake and increase cardiac output
  • Hypovolemic -> stop losses and replace deficits with blood or saline
  • Euvolemic (known cause): restrict water intake and treat cause
  • Euvolemic (SIADH): restrict fluids

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