Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HMS302 Endocrine System > Pituitary Disorders > Flashcards

Pituitary Disorders Flashcards

1
Q

Pituitary tumors (minority) cause clinical problems due to:

A
  • uncontrolled secretion of pituitary hormones.
  • local compression effects.
  • inadequate production of hormones by the remaining normal pituitary (i.e. hypopituitarism).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Tumors may be:

A
  • Small = micro-adenomas <10mm diameter
  • Large = macro-adenomas >10mm diameter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Name some Local compression effects of a pituitary tumor

A
  • Bitemporal hemianopia (optic chiasm)
  • Diplopia & CN III, IV & VI palsies
  • Headache
  • Increase prolactin (PRL) levels due to loss of dopaminergic inhibitory control.
  • If very large = altered hypothalamic control of appetite, thirst & somnolence.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Many hormones are released in either by a _______ or a _________ pattern & are regulated by feedback systems.

A

pulsatile, circadian

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Pituitary tumors are a relatively common incidental finding in the general population, only a minority cause clinical problems due to:

A
  • uncontrolled secretion of pituitary hormones
  • due to local compression effects
  • hypopituitarism = inadequate production of hormones by the remaining normal pituitary
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The vast majority of tumors are?

A

Benign

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Tumors may be

A
  • small = microadenomas <10mm diameter
  • large = macroadenomas >10mm diameter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Local compression effects of Pituitary tumors

A
  • failure of pituitary gland function
  • bitemporal hemianopia (lateral vision loss - optic chiasm)
  • diplopia (double vision - optic nerves)
  • CN III, IV & VI palsies
  • increase prolactin (PRL) levels
  • headache
  • if very large = can alter the hypothalamic control of appetite, thirst & somnolence (strong desire for sleep)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Uncontrolled hormone release occurs with tumors arising from the 5 types of cells:

A
  • corticotroph cells = ACTH excess = Cushing’s syndrome.
  • somatotroph cells = hGH excess = Acromegaly (adults) or Gigantism (kids)
  • lactotrophs = PRL excess = Prolactinoma
  • thyrotrophs = rarely hyperthyroidism = TSH-releasing tumors
  • gonadotroph = rare LH or FSH excess = ovarian hyperstimulation & testicular enlargement.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Uncontrolled hormone release occurs with tumors arising from the 5 types of cells:

A
  • corticotroph cells = ACTH excess = Cushing’s syndrome.
  • somatotroph cells = hGH excess = Acromegaly (adults) or Gigantism (kids)
  • lactotrophs = PRL excess = Prolactinoma
  • thyrotrophs = rarely hyperthyroidism = TSH-releasing tumors
  • gonadotroph = rare LH or FSH excess = ovarian hyperstimulation & testicular enlargement.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Some common pituitary tumors cause no apparent hormone excess & are referred to as ______________ tumors.

A

non-functioning tumors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Investigations of Pituitary tumor

A
  • MRI of the pituitary = superior to CT because it readily shows any significant pituitary mass. Microadenomas are very common on MRI (10%) = pituitary incidentalomas
  • visual field = Goldmann perimetry & using red pin for clinical assessment. Common defects = upper temporal quadrantanopia & bitemporal hemianopia.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The aim of therapy for pituitary tumors is to: (4)

A

(1) Reduce tumor bulk & relieve pressure on local structures.
(2) Restore excess hormone secretion to normal levels
(3) Eliminate associated co-morbidities & increased mortality resulting from hormone excess.
(4) Preserve or restore pituitary function.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Treatment of pituitary tumors includes:
- dependent on the etiology of the pituitary mass.

A
  • surgery
  • radiotherapy
  • medical therapy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Post-operative radiotherapy is used if?

A

Significant tumor bulk remains after surgery or the underlying disease is still active.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Radiotherapy results in?

A

Decline of residual pituitary function over many years & must be monitored.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Surgery is only required if the pituitary tumor is large enough to?
(2)

A
  • cause anatomical effects
  • secretion of excess hormones. Small tumors producing no significant symptoms, pressure or endocrine effects may be observed.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Surgery for pituitary tumor is via the _______ route, which is usually the treatment of choice.

A

trans-sphenoidal route

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Very large pituitary tumors are usually done through the ______ _______ route for surgery.

A

open trans-cranial (usually trans-frontal) route

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Radiotherapy

A
  • done by conventional linear accelerators or newer stereotactic techniques.
  • conventional regimen = involves a dose of 45Gy.
  • postoperative radiotherapy is used when the tumor bulk remains after surgery or the underlying disease is still active.
  • results in gradual decline or residual pituitary function over many years & must be monitored.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Medical therapy for pituitary tumor

A
  • Somatostatin analogs and/or dopamine agonists (can shrink specific tumor types)
22
Q

________ _________ are the most common mass lesion of the pituitary (90%)

A

Pituitary adenomas

23
Q

Craniopharyngioma

A
  • 1-2%
  • usually cystic hypothalamic tumor
  • arises from Rathke’s pouch
  • most common pituitary tumor in children
  • may present at any age
24
Q

Uncommon tumors include

A
  • meningiomas
  • gliomas
  • chondromas
  • germinomas
  • pinealomas
25
Q

Occasionally PRL & ACTH-secreting tumors present in an ________ manner which may?

A

aggressive manner which may require chemotherapy in addition to conventional treatment.

26
Q

Metastases occasionally present as apparent pituitary tumors, typically accompanied by?

A

headache & diabetes insipidus

27
Q

Panhypopituitarism

A

deficiency of all anterior pituitary hormones

28
Q

Panhypopituitarism is most commonly caused by:
(3)

A
  • pituitary tumors
  • surgery
  • radiotherapy
29
Q

ADH will only be significantly affected if?

A

the hypothalamus is involved or if there is an infiltrative/inflammatory process.

30
Q

Causes of Hypopituitarism (7)

A
  1. Congenital = isolated deficiency of pituitary hormones (e.g. Kallmann’s syndrome), POU1F1 mutations.
  2. Infective = basal meningitis, encephalitis, syphilis.
  3. Vascular = pituitary apoplexy (infarction of the pituitary), Sheehan’s syndrome, carotid artery aneurysm.
  4. Immunological = autoimmune hypophysitis, pituitary antibodies.
  5. Neoplastic = pituitary or hypothalamic tumor, craniopharyngioma, meningioma, lymphoma.
  6. Traumatic = skull fractures through base, surgery (especially transfrontal), perinatal trauma.
  7. Infiltrations = sarcoidosis, langerhans’ cell histiocytosis, hypophysitis = postpartum, giant cell.
31
Q

PROP1 gene

A

Provides instructions for making a protein that helps control the activity of many other genes.

32
Q

POU1F1 gene

A

Regulates the expression of several genes involved in pituitary development & hormone expression.

33
Q

Mutations in the PROP1 & POU1Fi genes

A

Prevents differentiation of anterior pituitary cells leading to deficiencies of hormones.

differentiation - process of cells, tissues & organs acquiring specialized features.

34
Q

Symptoms of deficiency of a pituitary-stimulating hormone are the _______ as those of primary deficiency of the peripheral endocrine gland.
- Example

A

same
- Example = TSH deficiency & primary hypothyroidism cause similar symptoms due to lack of thyroid hormone secretion.

35
Q

Treatment for Hypopituitarism

A
  • steroid & thyroid hormones are given as oral replacement drugs
  • androgens & estrogens for symptomatic control
  • LH & FSH analogs are used if fertility is desired.
  • GH therapy should be given to the growing child under appropriate specialist supervision.
36
Q

2 warnings necessary for the treatment of hypopituitarism

A
  1. Thyroid replacement should not commence until normal glucocorticoid function has been demonstrated or replacement steroid therapy is initiated.
    - may precipitate an adrenal crisis
  2. Glucocorticoid deficiency masks impaired urine concentrating ability.
    - Diabetes insipidus is apparent after steroid replacement.
37
Q

Symptoms for Acromegaly

A
  • Head & neck = changes in facial appearance, headaches, visual deterioration, deep voice, goitre.
  • General = weight gain, breathlessness, excessive sweating, joint pain, muscular weakness.
38
Q

Signs of Acromegaly

A
  • Facial = prominent supraorbital ridge, prognathism (protruding jaw), interdental separation, large tongue, visual field defects.
  • Hands = space-like hands & feet
  • General = hirsutism (thick hair growth on different body parts), thick greasy skin.
39
Q

Investigations for Acromegaly
(7)

A
  1. GH levels
  2. Glucose tolerance test
  3. IGF-1 levels
  4. Visual field examination
  5. MRI scan pituitary
  6. Pituitary function
  7. Prolactin levels
40
Q

GH levels - Acromegaly

A
  • a detectable value alone is non-diagnostic
  • normal adult levels < 0.5 microg/L (except during stress or a GH pulse)
41
Q

Glucose tolerance test - Acromegaly

A
  • is diagnostic if there is no suppression of Gh
  • about 25% of acromegalics have a positive diabetic glucose tolerance test
42
Q

IGF-1 levels - Acromegaly

A
  • are almost always increased in acromegaly
  • a normal IGF-1 + a random GH <1 microg/L may be taken to exclude acromegaly if the diagnosis is clinically unlikely.
43
Q

Management of Acromegaly
- indication & aim

A
  • Treatment is indicated in all except the elderly or those with minimal abnormalities.
  • Aim = to achieve a mean GH level <2.5 microg/L not always normal BUT considered a safe GH level. Also to have a normal IGF-1 level.
44
Q

Management of Acromegaly
(3)

A
  1. Surgery
    - trans-sphenoidal surgery is the appropriate 1st-line therapy.
    - transfrontal surgery is rarely required except for massive macroadenomas.
  2. Pituitary Radiotherapy
    - normally used after pituitary surgery fails to normalize GH levels.
    - combined with a somatostatin analog, dopamine agonist, or GH antagonist because of the slow biochemical response to radiotherapy.
  3. Medical Therapy
45
Q

Medical therapy - Acromegaly
3 receptor targets

A
  1. Pituitary somatostatin receptors
    - Octreotide & Lanreotide = monthly depot injections (slow release)
  2. Dopamine (D2) receptors
    - can be given to shrink tumors prior to definitive therapy OR to control symptoms & persisting GH secretion.
    - given alone, they reduce GH to safe levels in only a minority of cases but are useful for mild residual disease or in combination with somatostatin analogs.
    - bromocriptine 10-60mg daily
  3. GH receptors antagonists
    - Pegvisomant = genetically modified analog of GH
    - it doesn’t decrease GH levels or tumor size but normalizes IGF-1 levels (90%).
    - daily injection
46
Q

Prolactin (PRL) stimulates _______ ______ but also inhibits ______ _______. It is under tonic ________ inhibition.

A

milk secretion, gonadal activity, dopamine.

47
Q

Causes of Hyperprolactinemia
(3)

A
  1. Physiological
    - pregnancy, lactation, stress, sleep, exercise & coitus.
  2. Pathological
    - prolactinoma, co-secretion of prolactin in tumors causing acromegaly, PCOS, primary hypothyroidism, idiopathic hyperprolactinemia.
  3. Drug-induced
    - estrogens (contraceptive pill), dopamine antagonists, antidepressants (SSRIs), antiemetics (metoclopramide).
48
Q

In the presence of a pituitary mass on MRI, the level of PRL helps determine whether the mass is a…

A
  • prolactinoma
  • non-functioning pituitary tumor
49
Q

Strongly suggestive of a Prolactinoma

A

> 5000 mU/L + macroadenoma

> 2000 mU/L + microadenoma (or no radiological abnormality)

  • Macroprolactinoma >10mm in diameter
  • Microprolactinoma <10mm in diameter
  • Mesoadenomas approx. 10mm
50
Q

Treatment for Hyperprolactinemia
- goals?

A
  • reduce the size of the tumor
  • treat galactorrhea
  • reverse hypogonadism = avoid the long-term effects.

HMS302 Endocrine System (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions