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Phase 1b - Endocrinology > Pituitary Tumours > Flashcards

Pituitary Tumours Flashcards

-> Function of endocrine glands: Summarise the function of the key endocrine glands, including the synthesis, regulation and physiological effects of their hormones. -> Endocrine disorders: Describe the clinical features and treatment options of endocrine disorders.

1
Q

Somatotrophs release:

A

Growth hormone

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2
Q

Lactotrophs release:

A

Prolactin

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3
Q

Thyrotrophs release:

A

Thyroid stimulating hormone (TSH)

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4
Q

Gonadotrophs release:

A
  • Luteinising hormone (LH)
  • Follicle stimulating hormone (FSH)
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5
Q

Corticotrophs release:

A

ACTH

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6
Q

A functioning pituitary tumour on somatotrophs can lead to:

A

Acromegaly

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7
Q

A functioning pituitary tumour of the lactotrophs is referred to as?

A

Prolactinoma

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8
Q

A functioning pituitary tumour of the thyrotrophs is referred to as?

A

TSHoma

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9
Q

A functioning pituitary tumour of the gonadotrophs is referred to as?

A

Gonadotrophinoma

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10
Q

A functioning pituitary tumour of the corticotrophs is referred to as?

A

Corticotroph adenoma

Cause of Cushing’s Disease

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11
Q

What are pituitary tumours classified by (radiologically) (4)?

A
  • Size
  • Suprasellar (situated or rising above the sella turcica) or not
  • Compressing optic chiasm or not
  • Invading cavernous sinus or not
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12
Q

What is the size classification of a microadenoma?

A
  • < 1Omm (1cm)
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13
Q

What is the size classification of a macroadenoma?

A
  • > 1cm (10mm)
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14
Q

What are pituitary tumours classified by (in terms of function) (2)?

A
  • Excess secretion of a specific pituitary hormone
  • No excess secretion of pituitary hormone (non-functioning adenoma)
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15
Q

What are pituitary tumours classified by (in terms of malignancy) (2)?

A

Benign: Adenomas
Malignant: Carcinomas (very rare (< 0.5%))
* Mitotic index measured using Ki67 index – benign is < 3%

Pituitary adenomas can have benign histology but display malignant behaviour

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16
Q

How is the malignancy (mitotic index) of a pituitary adenoma measured?

A

ki67 index

Describing how many cells are dividing

< 3% is considered benign

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17
Q

What ki67 mitotic index classifies a pituitary adenoma as benign?

A
  • < 3%
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18
Q

What are the clinical presentations of a prolactinoma (5)?

A
  • Menstrual disturbance
  • Erectile dysfunction
  • Reduced libido
  • Galactorrhoea
  • Subfertility
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19
Q

How do the symptoms of prolactinoma arise (5 steps)?

A
  • Prolactinoma leads to hyperprolactinaemia
  • Prolactin binds to prolactin receptors on kisspeptin neurons in hypothalamus
  • Inhibits kisspeptin pulsative release
  • Decreases in downstream GnRH/LH/FSH/T/Oest
  • Oligo-amenorrhoea/Low libido/Infertility/Osteoporosis
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20
Q

Which hormone inhibits the pulsatile action of kisspeptin neurones?

A
  • Prolactin
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21
Q

What are the physiological causes of an elevated prolactin (3)?

A
  • Pregnancy / breast feeding
  • Stress: exercise, seizure, venepuncture (stress induced can lead to an increase in prolactin levels)
  • Nipple / chest wall stimulation
22
Q

What are the pathological causes of elevated prolactin other than a prolactinoma (3)?

A
  • Primary hypothyroidism (Due to increased TRH release)
  • Polycystic ovarian syndrome (PCOS)
  • Chronic renal failure
23
Q

What are the iatrogenic causes of elevated serum prolactin (5)?

A
  • Antipsychotics
  • Selective serotonin re-uptake inhibitors (SSRIs)
  • Anti-emetics
  • High dose oestrogen
  • Opiates
24
Q

What investigations are recommended in suspection of prolactinoma (2)?

A
  • Serum [prolactin]
  • Pituitary MRI
25
Q

What parameter of serum prolactin is associated with a prolactinoma?

A
  • > 5000mu/L

Serum prolactin is proportional to tumour size

26
Q

How is the majority of prolactin transported within the serum?

A
  • Monomeric prolactin that is biologically active
27
Q

What are the two possible outcomes of an elevation of serum prolactin yet there are no clinical consistent features (false positives)?

A
  • Macroprolactin
  • Stress of venipuncture
28
Q

What is macroprolactin?

A
  • A polymeric form of prolactin (An antigen-antibody complex of monomeric prolactin and IgG)

Normally < 5% of circulating prolactin

29
Q

How can a stress of venepuncture be excluded from true elevation in serum prolactin?

A
  • Exclude by a cannulated prolactin series
    • Sequential serum prolactin measurement 20 minutes apart with an indwelling cannula to minimise venepuncture stress
30
Q

How is a true pathological elevation of serum prolactin diagnosed?

A
  • Conduct pituitary MRI
31
Q

What is the first line of treatment in regards to prolactinomas?

A
  • Dopamine receptor agonists (cabergoline or bromocriptine)
32
Q

What is the aim with using cabergoline to manage prolactinoma?

A
  • Normalise serum prolactin and shrink prolactinoma
33
Q

How do dopamine receptor agonists work in the management of prolactinoma?

A
  • Bind to D2 receptors on lacotrophs therefore exerting an inhibitory effect on prolactin release
34
Q

What are the symptoms associated with acromegaly (8)?

A
  • Sweatiness
  • Headache
  • Coarsening of facial features: Macroglossia / Prominent nose
  • Large jaw - prognathism
  • Increased hand & feet size
  • Snoring & obstructive sleep apnoea
  • Hypertension
  • Impaired glucose tolerance / diabetes mellitus
35
Q

What is the main risk that is increased in patients with untreated acromegaly?

A
  • Increased cardiovascular risk
36
Q

Which factors are released from the liver upon stimulation of growth hormone (2)?

A
  • IGF-1
  • IGF-2
37
Q

How can acromegaly be diagnosed (3)?

A
  • Elevated serum IGF-1
  • Failed suppression of GH following oral glucose load (OGTT) - paraxodical rise
  • Once confirm GH excess, pituitary MRI to visualise pituitary tumour

GH pulsatile -> so random measurement unhelpful

38
Q

What is the first line of treatment in patients with acromegaly?

A
  • Trans-sphenoidal pituitary surgery

Aim to normalise serum GH and IGF-1

39
Q

What pharmacological treatments can be prescribed for acromegaly?

A
  • Somatosatin analogues (octreotide)
  • Dopamine agonists (cabergoline)

GH secreting pituitary tumours frequently express D2 receptors

40
Q

What is Cushing’s syndrome?

A

An excess cortisol

41
Q

What is Cushing’s disease?

A
  • Cushing’s Syndrome due to a corticotroph adenoma
42
Q

What are the clinical features Cushing’s syndrome (13)?

A
  • Mental changes (depression)
  • Osteoporosis
  • Impaired glucose tolerance (diabetes)
  • High BP
  • Proximal myopathy
  • Red cheeks
  • Fat pads
  • Thin skin
  • Easy bruising
  • Moon face
  • Purple striae
  • Pendulous abdomen
  • Poor wound healing
43
Q

What are the causes of Cushing’s disease divided into (2)?

A
  • ACTH Independent
  • ACTH Dependent
44
Q

What are the ACTH independent causes of Cushing’s syndrome (2)?

A
  • Oral corticosteroids
  • Adrenal adenoma or carcinoma
45
Q

What are the ACTH dependent causes of Cushing’s syndrome (2)?

A
  • Corticotroph adenoma (Cushing’s Disease)
  • Ectopic ACTH (Lung cancer)
46
Q

What is the most common cause of Cushing’s syndrome?

A
  • Oral corticosteroids
47
Q

How is Cushing’s syndrome investigated (3)?

A
  • Elevation of 24h urine free cortisol - increased cortisol secretion
  • Elevation of late night cortisol - salivary or blood test - loss of diurnal rhythm
  • Failure to suppress cortisol after oral dexamethasone (exogenous glucocorticoid) increased cortisol secretion
48
Q

If Cushing’s syndrome is confirmed, how can one distinguish between ACTH dependent / ACTH independent cause?

A
  • Once confirmed hypercortisolism, measure ACTH
  • If ACTH high, pituitary MRI ACTH dependent
49
Q

What is the main clinical feature often presented alongside a non-functioning pituitary adenoma?

A
  • Bitemporal hemianopia
50
Q

What are the not-so-common clinical features presented alongside a non-functioning pituitary adenoma?

A
  • Hypopituitarism
  • Serum prolactin can be raised
51
Q

How are non-functioning pituitary adenomas managed?

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

Phase 1b - Endocrinology (19 decks)

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