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4 > Anterior pituitary disorders > Flashcards

Anterior pituitary disorders Flashcards

1
Q

Causes of increased prolactin

A

Stalk compression
hypothalamic injury
prolactinoma, cosecretion with pituitary adenoma
hypothyroid

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2
Q

Effects of increased prolactin

A

amenorrhea
infertility
impotence
galactorrhea

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3
Q

Causes of decreased prolactin

A

pregnancy: progesterone inhibits lactation

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4
Q

GH increase cause

A

tumour (acremegaly, adult)

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5
Q

ACTH increase causes

A

pituitary adenoma
ectopic ACTH tumours
–> Cushing’s disease/syndrome

Addison’s disease will increase ACTH but a decrease in cortisol

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6
Q

ACTH decrease reasons

A

autosomal cortisol secreting tumours –> secondary adrenal insufficiency

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7
Q

LH increase reasons

A

gonadotroph cell adenoma (rare)

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8
Q

FSH decrease causes

A

pituitary failure

–> secondary hypogonadism, infertility

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9
Q

TSH increase causes

A

primary hypothyroidism (TSH > 10)

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10
Q

TSH decrease causes

A 
Primary hyperthyroidism (TSH < 0.1)
--> secondary hypothyroidism
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11
Q

Usual order of loss of pituitary function

A 
GH
LH
FSH
TSH
ACTH
PRL
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12
Q

Causes of hypopituitarism

A

Vascular: aneurysm, arteriosclerosis
I: sarcoidosis, histiocytosis, AI
N: pituitary carcinoma, craniopharyngioma, pituitary tumour, metastatic carcinoma, pinealoma
Drug-related
Radiation
CV, autoimmune/allergic
Head truma, post-partum pituitary necrosis
ENdocrine: DM, hemoglobinopathies, Fe overload, hypothalamic disease, isolated hormone deficiency
Genetic - familial hypopituitaris

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13
Q

Testing GH axis

A

measure IGF1

stimulation test: insulin-induced hypoglycemia, glucagon + arginine
suppression test: gluose suppression test

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14
Q

Testing gonadotropic axis

A

measure LH FSH testosterone estradiol

stimulation test: GnRH
suppression test: excess LH/FSH extremely rare

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15
Q

Testing thyroid axis

A

TSH, free T4

stimulation test: administer TRH

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16
Q

Testing adrenocortical axis

A

measure ACTH, am cortisol, urine cortisol

Stimulation test: insulin-induced hypoglycemia, ACTH stress test
suppression test: dexamethasone

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17
Q

Testing prolactin axis

A

measure prolactin

stimulation test: TRH

18
Q

Triple bolus test

A

insulin, TRH, GnRH

19
Q

Clomiphene stimulation test

A

interrupts negative feedback loop –> stimulates gonadotropin release from pituitary

20
Q

GH secreting tumou frequency

A

8-10%

21
Q

Prolactinoma frequency

A

30%, most common

22
Q

Mixed GH-prolactin adenoma frequency

A

4.5%

23
Q

ACTH-secreting tumour frequency

A

14%

24
Q

Thyrotroph tumour frequency

A

rare <1%

25
Q

Gonadotropic tumour freq

A

rare: 2.5%

26
Q

Granular cell tumour frequency

A

1-2% of unselected biopsies, most frequent of posterior ptiuitary

27
Q

Craniopharyngioma

A

sella turcica epithelial tumour
disturbance of HPA axis, vision, CSF flow
heavily calcified and hard to operate on

3-5% of all intracranial neopaslms

28
Q

Consequences of GH excess

A

before closure of epiphyseal plate: gigantism
after closure of epiphyseal plates: acromegaly
- thickened sweat skin, large feet, hands, skull and jaw, cardiomegaly, organomegaly, hypertension, arthritis, carpal tunnel syndrome, paresthesias, fatigue, glucose intolerance
may have mass effects of pituitary adenoma

29
Q

Consequences of TSH excess

A

secreting tumours are rare
causes goiter and hyperthyroidism
weight loss, nervousness, rapid heartbeat, difficulty sleeping, frequent bowel movements
women: amenorrhea

30
Q

Consequences of excess sex hormones

A

precocious puberty

Initiation of sexual maturation before puberty (8 girls 9 boys)

31
Q

Pituitary mass effect

A

hypothalamus
compress optic chiasma
compres normal pituitary tissue
compress pituitary stalk - block GnRH, dopamine transport

32
Q

Management of small pituitary tumours

A

<10 mm and no hormonal hypersecretions

  • 2-4 mm: no further testing
  • 5-9 mm: MRI 1-2x over next 2 years, if lesion stable, reduce frequncy
33
Q

Pit tumour pharmacotherapy

A

Most useful in prolactinomas
May use in other tumours as an adjunct to surgery/radiotherapy
Options:
Dopamine agonists –> prolactinomas, less useful for GH
Somatostatin analogue –> acromegaly
Pegvisomant (GH receptor blocker) –> acromegaly refractory to octreotide
Ketoconazole, metyrapone, mitotane –> cushing’s disease

34
Q

Pituitary surgery

A

for large tumours and other hyperfunctional tumours

Transphenoidal : used in 95% cases

Indications:
1st line for symptomatic pituitary adenomas
used when medical/radiotherapy fails
provides prompt relief
indictaed in pituitary apoplexy with compressive symptoms

35
Q

Pituitary radiotherapy

A

reserved for patients with large tumours and/or persistent hormonal hyperfunction despite surgical intervention
2 types:
1)conventional: slow response, 80% success in acromegaly, 50% cushing’s
- high rate of hypopituitarism and other complications possible
2) gamma knife radiosurgery: stereotactic CT guided cobalt 60 gammar adiation to narrowly focused area
success: 70% acromegaly, 70% cushings
- lower complication rate, still high for hypopituitarism

36
Q

Acromegaly therapy

A

1) surger
2) octreotide - shrinks tumour
3) GH receptor antagonist - pegvisomat

37
Q

Prolactinoma therapy

A

1) dopamine agonist
2) surgery
3) radiation

38
Q

Hypogonadotropic hypogonadism

A

Low LH and FSH
Congenital or acquired
Acquired more common

39
Q

Congenital causes of hypogonadotropinism

A

Idiopathic - most often
Familial hypogonadotropic hypogonadism - can be tarnsmitted as X-linked, autosomal recessive, or dominant
- mutations in GnRH receptor, LH/FSH mutation, etc

40
Q

Acquired causes of low LH and FSH

A

1) severe illness, stress, malnutrition, exercise - reversible
2) dopamine antagonists/serotonin agonists –> increased prolactin inhibits GnRH
3) Hyperprolactinemia - as above, or may destroy surrounding gonadotropes
4) Sellar Mass lesions: should be distinguished from prolactinomas
5) hemochromatosis

41
Q

Pituitary investigations

A

structural imaging –> CT/ MRI (best)
Functional evaluation –> PET-FDG
MACROadenomas usually nonfunctional
MICROadenomas usually functional

42
Q

Complete androgen insensitivity

A 
X-linked recessive
normal female external genitalia
absent vagina/short vagina with blind end
testes in abdomen, inguinal canals, or labia majora
normal Leydig cells + no spermatogenesis
Normal breast development
reduced/absent pubic hair
normal female psychological development
testosterone normal or Increased
LH increased
increased estrogen

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