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Endocrine > 169. Hypothalamic-Pituitary Pathophysiology > Flashcards

169. Hypothalamic-Pituitary Pathophysiology Flashcards

1
Q

Caused by:

  • h/o infarction, surgery, irradiation of tumor
  • medical therapy of tumor
  • end stage of hypophysitis

Results in hypopituitarism, rare visual defects, CSF in sella turcica

A

Secondary Empty Sella Syndrome

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2
Q

Clinical manifestations d/t direct or associated hormone effects

Women:

  • oligo-amenorrhea/infertility
  • galactorrhea
  • estrogen deficiency
  • osteopenia
  • diminished libido/dyspareunia
  • acne/hirsutism

Men:

  • decreased libido
  • ED
  • gynecomastia
  • galactorrhea
  • infertility
  • osteopenia
A

Hyperprolactinemia

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3
Q

Medical therapy for acromegaly

A

Cabergoline - dopamine agonist

Octreotide, lanreotide - somatostatin analogs

Pegvisomant - GH Receptor antagonist

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4
Q

Resistance to ADH

  • defective V2 receptor signaling
  • congenital defect

Caused by:

  • drugs
  • hypercalciuria
  • hypokalemia
  • mutation of V2 receptor
  • Aquaporin 2 mutation
A

Nephrogenic Diabetes Insipidus

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5
Q

Over 90% in women Associated w/ multiple hormonal abnormalities:

  • Hypogonadotrophic hypogonadism (amenorrhea)
  • Early satiety
  • Temp dysregulation (hypothermia)

Hormonal abnormalities reversible w/ weight gain

A

Anorexia nervosa

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6
Q

Dopamine agonists used to treat hyperprolactinemia

Efficacious in normalizing prolactin levels

Efficacious in shrinking tumors

Cannot nurse while on these medications d/t suppressed prolactin

A

Cabergoline and bromocriptine

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7
Q

Manifestations:

  • prepubertal
  • postpubertal

Diagnosis:

  • measure LH, FSH, estradiol, testosterone

Common:

  • mass lesions
  • reversible weight loss and increased exercise
  • idiopathic

Treatment:

  • Men: testosterone
  • Women: birth control
  • Women wanting to be pregnant: stimulate gonad w/ gonadotrophins
A

Gonadotrophin deficiency

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8
Q

Associated w/ failure of postpartum lactation

Usually associated with loss of other hormones

  • Sheehan’s syndrome
  • Lymphocytic hypophysitis
  • ACTH loss
  • other mass lesions of the sella

NO treatment

A

Hypoprolactinemia

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9
Q

Clinical characteristics:

  • male >> female
  • >40yo

Normal past history of gonadal function

  • normal puberty and fertility

Enormous pituitary size causing mass effects

  • visual field defects
  • hypopituitarism
  • hyperprolactinemia
  • extrasellar extension on MRI

Can make isolated alpha and beta subunits or intact LH or intact FSH

A

Gonadotroph adenomas

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10
Q

HA Visual field defects

Cranial nerve palsies

Hypopituitarism

Diabetes Insipidus

Temp dysregulation and dysregulation of food intake (rare)

A

Mass effects of sellar lesions

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11
Q

Congenital malformations

  • often related to transcription factor mutations

Hydrocephalus Tumors

  • craniopharyngiomas
  • pituitary adenomas
  • dysgerminomas Trauma
  • surgery
  • irradiation
  • external Infiltrative disease
  • sarcoidosis
  • Langerhans cell histiocytosis

Inflammation/infection

  • encephalitis
  • meningitis
A

Etiology of Hypothalamic Dysfunction

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12
Q

Manifestation:

secondary hypoadrenalism

  • lose cortisol and adrenal androgens
  • aldosterone relatively normal (from RAS)
  • Na+ low from lack of cortisol
  • K+ normal bc aldosterone is normal

Inability to respond to stress

  • failure to treat –> death

Diagnosis:

  • low cortisol and ACTH
  • decreased response to hypoglycemia
  • decrease cortisol response to injection Cotrosyn (synthetic ACTH) if chronic condition —> normal response if acute condition
A

ACTH deficiency

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13
Q

Inability to suppress GH levels during an oral glucose tolerance test

Elevated serum IGF-1 levels MRI to identify location, size of tumor

  • 60% macroadenomas

Visual fields if tumor found to be abutting chiasm

Evaluate for hypopituitarism if macroadenoma

A

Diagnostic testing for acromegaly

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14
Q

Normally caused by a pituitary tumor

  • also caused by a craniopharyngioma
  • can also be idiopathic

Increased fat mass

Decreased muscle mass

Decreased energy, increased fatigue

Poor QOL

A

Adult GH deficiency

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15
Q

Medical therapies for Cushing’s

A

Steroidogenesis blockers

Steroid receptor antagonist

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16
Q

GH receptor antagonist used to treat acromegaly

Less activation –> less IGF-1 production

A

Pegvisomant

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17
Q

Deficiency of vasopressin secretion or action

Polyuria - large volume of dilute urine

Polydipsia - increased thirst

A

Diabetes Insipidus

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18
Q

Hypopituitarism

Disordered vasopressin regulation

Hyperprolactinemia

Other hypothalamic dysfunction if very large and bilateral

  • food intake
  • temperature dysregulation
A

Manifestations of hypothalamic disease

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19
Q

Mutation in Type 1A subunit of Protein Kinase A (PRKAR1A)

Pituitary adenoma in 10% (GH producing)

Spotty skin pigmentation

Myxomas

Schwannomas

Pigmented nodular adrenal cortical disease causing Cushing’s syndrome in 30%

A

Carney Complex

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20
Q

Mutations in HESX1, SOX2, SOX3, OTX2

Absent septum pellucidum

Agenesis of corpus callosum

Optic nerve dysplasia

Hypothalamic developemental dysfunction leads to hypopituitarism

Variable presentation

A

Septo-Optic Dysplasia

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21
Q

Pituitary transcription factor mutation of __ GH, TSH, PRL deficiencies

A

Pit-1

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22
Q

Infiltrative hypothalamic disease

  • often presents in middle age

May be pulmonary interstitial disease

  • get diffusing capacity measurement

Osteolytic lesions, especially in jaw

Treat w/ alkylating agents, focal irradiation, vinca alkaloids

A

Langerhans Cell Histiocytosis

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23
Q

Asymptomatic Symptomatic d/t mass effects

Primary therapy is surgery

A

Nonfunctional pituitary adenomas

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24
Q

Prolactinomas

  • continued growth despite medical therapy and surgery GH, ACTH, and TSH secreting pituitary adenomas
  • persistent hormone secretion despite surgery
  • often used in conjunction with medical therapy
  • primary therapy when surgery is contraindicated

Clinically nonfunctional adenomas

  • tumor recurrence
A

Indications for radiotherapy

25
Q

Inflammatory destruction of pituitary often with ACTH loss

A

Lymphocytic hypophysitis

26
Q

Pituitary transcription factor mutation of __ GH, TSH, PRL, LH, FSH deficiencies

A

Prop-1

27
Q

Germline mutations in gene for AIP

  • tumor suppressor
  • found in 1/3 of patients
  • most commonly in those with GH and PRL producing tumors (pituitary tumors)

Often large tumors presenting in childhood

A

Familial Isolated Pituitary Adenoma (FIPA) Syndrome

28
Q

In men:

  • lack of libido, impotence, infertility, decreased hair growth, osteoporosis

In women:

  • lack of libido, oligo/amenorrhea, infertility, osteoporosis
A

Postpubertal gonadotrophin deficiency

29
Q

Due primarily to prior treatment with glucocorticoids which suppress the HPA axis for up to a year

With mass lesions, a late loss

Treatment:

  • In the setting of hypopituitarism with multiple deficiencies, always replaces with hydrocortisone first
  • no need for mineralocorticoid
A

ACTH deficiency

30
Q

Usually caused by prolactin-secreting pituitary adenomas

Also caused by decrease dopamine getting to the normal lactotroph cells

  • hypothalamic tumors or infiltrative disease
  • meds: antipsychotics, verapamil, metoclopramide
A

Hyperprolactinemia

31
Q

2 main transcription factors involved in hypothalamic development and pituitary cell differentiation

A

Prop-1 and Pit-1

32
Q

Decreases the pulsatile release of GnRH from the hypothalamus leading to hypogonadism

A

Hyperprolactinemia

33
Q

Usually functional and reversible

D/t stress/illness

Seen w/ weight loss

Seen in individuals with increased exercise habits

A

Acquired hypogonadotropic hypogonadism

34
Q

Manifestation: secondary hypothyroidism

Diagnosis: low T3 and T4, low/normal TSH

Treatment: l-thyroxine - dose adjusted based solely on T4 levels and not TSH levels

A

TSH deficiency

35
Q

Integration of signals in ___ causes increase in food intake

Damage to this area causes lack of appetite and weight loss

A

Lateral hypothalamus

36
Q

Pituitary necrosis occurring w/in a few hours of delivery and generally associated with obstetric hemorrhage

  • hypotension –> occlusive vasospasm –> ischemic necrosis of pituitary

Acute: w/in 30 days of delivery

  • hypotension, tachycardia, failure to lactate

Chronic: months to years later

  • varying degree of hypopituitarism

May have partial to complete DI, which must be looked for

A

Sheehan’s Syndrome

37
Q

Mutations found in the alpha subunit of the Guanine nucleotide binding stimulatory regulatory protein (Gs) that couples the GHRH receptor to adenyl cyclase in pituitary GH-secreting adenomas in about 40% of patients w/ acromegaly

Mutations result in unregulated, high activity of adenyl cyclase and secretion of GH and cell proliferation

A

GSP mutation in acromegaly

38
Q

Diagnostic test used to see if GH and ACTH response is adequate in individuals Inject insulin into a non-diabetic pt

A

Insulin-induced hypoglycemia

39
Q

HTN, cardiomyopathy, valvular disease

Cerebrovascular events and HA

Hypogonadism

Arthritis

  • GH stimulates cartilage growth

Colon polyps

Glucose intolerance/DM

Respiratory complications/sleep apnea

A

Acromegaly comorbidities

40
Q

Primary deficiency of ADH

  • destruction of posterior pituitary
  • increased degradation by placenta
  • gestational

Caused by:

  • tumors
  • trauma
  • infections
  • granulomatous diseases
  • infundibulohypophysitis
  • genetic
  • idiopathic
A

Central Diabetes Insipidus

41
Q

Can be isolated to CNS

  • infiltrative hypothalamic disease CSF pleiocytosis, increased ACE levels

Treat w/ steroids

A

Sarcoidosis

42
Q

Syndrome caused by hemorrhage into tumor

Symptoms and signs:

  • HA
  • Altered consciousness
  • Visual symptoms
  • Stiff neck
  • Fever
  • Nausea and vomiting
  • Hypotension Hypopituitarism is common SIADH/DI rare
A

Pituitary apoplexy

43
Q

Congenital hypogonadotrophic hypogonadism

D/t mutation in gene for protein that facilitates migration of GnRH and olfactory neurons from olfactory placode to anterior septal region of hypothalamus and olfactory bulbs

Associated w/ anosmia and late puberty

A

Kallmann’s Syndrome

44
Q

Medical therapy for TSH-secreting tumors

A

Somatostatin analogs - octreotide and lanreotide

45
Q

Starting dose

  • 150-300 micrograms/day regardless of body weight

Evaluate every 1-2 month for clinical symptoms and measurement of IGF-1 levels

Increase dose to obtain IGF-1 levels in middle of normal range (age and sex-adjusted) while avoiding symptoms

Older individuals tend to need smaller doses

A

GH treatment

46
Q

Cysts lined with squamous epithelium and contain serous or oily fluid

On MRI, nodular, lobular well-demarcated cystic mass, often w/ rim enhancement

Predominantly suprasellar with some intrasellar component

Cause varying degrees of hypopituitarism, hyperprolactinemia, and DI

  • often causes HA, visual field defects, and may cause hydrocephalus
A

Craniopharyngioma

47
Q

Caused by:

  • diaphragmatic defect
  • congenital
  • benign intracranial hypertension
  • congenital embryopathy
  • txn factor mutations
  • asymptomatic infarction in many adults
  • autoimmune

Results in hypopituitarism, rare visual defects, CSF in sella turcica

A

Primary Empty Sella Syndrome

48
Q

<8yo in girls, <10yo in boys

Central (hypothalamic) vs. Peripheral (gonad, adrenal)

More common in girls

  • 1/3 have organic disease (esp. boys)

Mechanisms triggering early gonadotrophin secretion largely unknown

Rare:

  • hamartoma or dysgerminoma secreting GnRH
A

Precocious Puberty

49
Q

Feedback signals in ___ cause decrease in food intake

Damage to this area causes obesity

A

Ventromedial hypothalamus

50
Q

Infiltrative hypothalamic disease

Often make hCG

  • measure in CSF

Usually very radiosensitive

A

Dysgerminoma

51
Q

Order of pituitary hormones lost after radiotherapy or with pituitary injuries

A

GH, then LH/FSH, ACTH, TSH

52
Q

Common sequela of irradiation therapy

A

Hypopituitarism

53
Q

Normally is asymptomatic if water intake is reduced proportionally

However, if water intake is maintained or increased

  • hyponatremia
  • water intoxication: HA, nausea, confusion, death
A

Excessive vasopressin secretion (SIADH)

54
Q

Defective GH receptor

  • AR disease

Unable to generate IGF-1

Treat w/ IGF-1 treatment

A

Laron’s Syndrome (GH Insensitivity Syndrome)

55
Q

Mutation in menin gene causing pituitary tumor

  • tumor suppressor

Occurs w/ parathyroid and pancreatic tumors (PPP)

A

MEN 1

56
Q

Pituitary transcription factor mutation of __ Variable deficiencies

  • GH, TSH, ACTH, FSH, LH, vasopressin
  • in association w/ midline brain abnormalities and optic nerve hypoplasia
A

HESX1

57
Q

Treatment of Central Diabetes Insipidus

Urine output decreases to normal in 1-2 days

Water retention and resultant fall in serum sodium is minimal

A

Desmopressin (DDAVP)

58
Q

Used acutely in hospital to treat SIADH

  • vasopressin blocker
A

Conivaptan

Endocrine (26 decks)

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