Brainscape's Knowledge GenomeTM

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


See full index

BRS Year 2 > Pituitary Tumours > Flashcards

Pituitary Tumours Flashcards

1
Q

What cells are in the anterior pituitary and what hormones do they produce?

A

Somatotrophs- growth hormone (somatotorophin)

Lactotrophs- prolactin

Thyrotrophs- Thyroid stimulating hormone (TSH)

Gonadotrophs- LH and FSH

Corticotrophs- Adrenocorticotropic hormone

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

What functioning pituitary tumours can form in the anterior pituitary cells ?

A 
Somatotrophs- acromegaly
Lactotrophs- Prolactinoma 
Thyrotrophs- TSHoma
Gonadotrophs- Gonadotropinoma
Corticotrophs- Cushings disease (corticotroph adenoma)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How is a pituitary tumour appear radiologically (MRI) ?

A

Size:

  • Microadenoma <1cm (10mm)
  • Macroadenoma >1cm (10mm)

Sellar (pituitary found within sellar turcica) or suprasellar (above the sellar)

Compressing optic chiasm or not

Invading cavernous sinus or not

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

What is the function of a pituitary tumour?

A

Excess secretion of a specific pituitary hormone
eg prolactinoma

If there’s no excess secretion of pituitary hormone its called non Functioning Adenoma

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

What type of pituitary tumour is rare?

A

Pituitary carcinoma very rare (<0.5% of pituitary tumours)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How is mitotic index of pituitary tumor measured?

A

Mitotic index measured using Ki67 index – benign is <3%

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

What happens in hyperprolactinemia?

A
  1. Hypothalamus: Prolactin binds to prolactin receptors on kisspeptin neurons in hypothalamus
  2. Inhibits kisspeptin release.
  3. Ant. pituitary gland: Decreases in downstream GnRH/LH/FSH/T/Oest
  4. Gonads: Oligo-amenorrhoea/Low libido/Infertility/Osteoporosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a prolactinoma?

A

Commonest functioning pituitary adenoma
Usually serum [prolactin] >5000 mU/L
Serum [prolactin] proportional to tumour size (more prolactin, bigger the tumour)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does a prolactinoma present?

A 
Menstrual disturbance
Erectile dysfunction
Reduced libido
Galactorrhoea (production of milk outside of pregnancy)
Subfertility
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are other causes of elevated prolactin?

A

Physiological

  • Pregnancy/breastfeeding
  • Stress: exercise, seizure, venepuncture
  • Nipple/chest wall stimulation

Pathological

  • Primary hypothyroidism
  • Polycystic ovarian syndrome
  • Chronic renal failure

Iatrogenic

  • Antipsychotics
  • Selective serotonin re-uptake inhibitors
  • Anti-emetics
  • High dose oestrogen
  • Opiates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Is there an elevation in prolactin throughout the day?

A

It has no diurnal variation

It is possible to get lots of false positives for elevated prolactin so confirm the true elevation

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

If a patient has no clinical features consistent with a prolactinoma what other possible options are there?

A

Macroprolactin or stress of venepuncture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is macroprolactin?

A

Majority of circulating prolactin is monomeric & biologically active
Macroprolactin is ‘sticky prolactin’ (a polymeric form of prolactin)
An antigen–antibody complex of monomeric prolactin and IgG forms (normally <5% of circulating prolactin)
This can be recorded on assay as elevation of prolactin – needs alternative method to confirm
You should reassure the patient that their prolactin levels are normal

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

How can stress of venepuncture cause elevated prolactin?

A

Increased stress can cause an increase in prolactin
In order to eliminate this factore sequential serum prolactin measurements should be taken 20 mins apart with an indwelling cannula to minimise venepuncture stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What should you do when you have confirmed true elevation of serum prolactin?

A

Organise a pituitary MRI

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

What is the first line treatment for a prolactinoma?

A

First-line treatment is medical not surgical
Dopamine receptor agonists is the main treatment (e.g. Cabergoline (bromocriptine))
Its safe in pregnancy
The aim is to normalise serum prolactin & shrink prolactinoma

17
Q

How should medication be adjusted for a microprolactinoma vs macroprolactinoma?

A

Microprolactinomas will need smaller doses than macroprolactinomas

18
Q

How do dopamine receptor agonists work?

A

The agonist binds to the D2 receptor on anterior pituitary lactotroph suppressing the release of prolactin

19
Q

What does a pituitary tumour secreting excess GH cause?

A

Gigantism in children (grow tall)

Acromegaly in adults (don’t grow taller because epiphyseal plates have fused)

20
Q

What are symptoms of acromegaly?

A 
Sweatiness
Headache
Coarsening of facial features:
- Macroglossia
- Prominent nose
Large jaw - prognathism
Increased hand and feet size
Snoring & obstructive sleep apnoea
Hypertension
Impaired glucose tolerance/diabetes mellitus
21
Q

What is the mean time to diagnose from onset of acromegaly symptoms?

A

10 years

22
Q

What is the mechanism of GH action?

A

Anterior pituitary releases GH which acts on liver causing elevated levels of IGF-1 and IGF-2 to be produced
GH and IGF-1 act on body tissues causing growth and development

23
Q

How is acromegaly diagnosed?

A 
GH is pulsatile so measuring it is unhelpful
Instead glucose (75g oral load) is given. If the patient has acromegaly there will be a paradoxical rise in GH (in a healthy patient GH falls after glucose given)
24
Q

What scan should be carried out after confirmation of GH excess?

A

MRI to visualise pituitary tumour

25
Q

How is acromegaly treated?

A
  1. First-line treatment is surgical – trans-sphenoidal pituitary surgery
    The aim to normalise serum GH and IGF-1
  2. We can use medical treatment prior to surgery to shrink tumour or if surgical resection incomplete
    E.g. Somatostatin analogues eg octreotide – ‘endocrine cyanide’
    Dopamine agonists eg cabergoline (GH secreting pituitary tumours frequently express D2 receptors)
  3. Radiotherapy (slow)
26
Q

What causes cushing’s syndrome?

A

Occurs due to an excess of cortisol or other glucocorticoid

Causes include:

  • Taking steroids by mouth (common)
  • Pituitary dependent Cushing’s disease (pituitary adenoma)
  • Ectopic ACTH (lung cancer)
  • Adrenal adenoma or carcinoma
27
Q

How can we categorize causes of cushing’s syndrome?

A

The causes can be catagorised as ACTH dependent or independent:

ACTH dependent:

  • Cushing’s disease (corticotroph adenoma)
  • Ectopic ACTH (lung cancer)

ACTH independent
Taking steroids by mouth (common)
Adrenal adenoma or carcinoma

28
Q

What is the difference between cushing’s syndrome and cushing’s disease?

A

Cushing’s syndrome = excess cortisol

Cushing’s disease is due to a corticotroph adenoma secreting ACTH

29
Q

How would we diagnose cushing’s disease?

A

We’d expect an elevation of 24 hour urine free cortisol (increased cortisol secretion)
There would also be an elevation of late night cortisol (salivary or blood test) indicating a loss of diurnal rhythm
We can also give patient oral dexamethasone (exogenous glucocorticoid). Failure to suppress this indicates cushing’s disease

30
Q

What should be tested once we have confirmed hypercortisolism in cushing’s disease?

A

Once confirmed hypercortisolism, measure ACTH

If ACTH high, pituitary MRI ACTH dependent

31
Q

What are features of a non-functioning pituitary adenoma?

A

Don’t secrete and specific hormone
Often present with visual disturbance (bitemporal hemianopia)
Can be present with hypopituitarism
Serum prolactin can be raised (as dopamine cant travel down stalk)

32
Q

How can large non-functioning pituitary adenomas be treated?

A

Trans-sphenoidal surgery needed for larger tumours, particularly if visual disturbance

BRS Year 2 (110 decks)

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