**_🧪Endocrinology🧪 - Pituitary tumours

Question 1

What is the name of the condition caused by a functioning somatotroph tumour?

Answer 1

Acromegaly/gigantism(in children)

Question 2

What is the name of a functioning lactotroph tumour?

Answer 2

Prolactinoma

Question 3

What is the name of a functioning thyrotroph tumour?

Answer 3

TSHoma

Question 4

What is the name of a functioning gonadotroph tumour?

Answer 4

Gonadotrophinoma

Question 5

What is the name of a functioning corticotroph tumour?

Answer 5

Cushing’s disease (corticotroph adenoma)

Question 6

What are the 3 categories by which pituitary tumours can be classified?

Answer 6

Radiologically (MRI)
Function
Benign or malignant

Question 7

How can pituitary tumours be classified radiologically?

Answer 7

Size:
-microadenoma <1cm/10mm
-macroadenoma >1cm/10mm
Sellar or supresellar
Compressing optic chiasm or not
Invading cavernous sinus or not

Question 8

How can pituitary tumours be classified by function?

Answer 8

Excess secretion of a specific pituitary hormone, named after that hormone (e.g. prolactinoma)
OR
No excess secretion of pituitary hormone (non functioning adenoma)

Question 9

How can pituitary tumours be classified as benign or malignant?

Answer 9

Pituitary carcinoma is very rare (<0.5%)
Pituitary tumours can have benign histology but display malignant behaviour - space is so confined than any growth will be invasive/aggresive

Question 10

What kind of pituitary tumour is shown here, and how would the patient be presenting?

Answer 10

Tumour shown is suprasellar (expanded beyond the sella turcica) and is compressing the optic chiasm significantly
Macroadenoma
Patient extremely likely to be reporting visual defects (e.g. bitemporal hemianopia)

Question 11

What would be the effect of a prolactinoma?

Answer 11

Greatly increased prolactin levels
Prolactin inhibits kisspeptin release, so also shut down of the GPH axis

Question 12

What are some key facts about prolactinomas?

Answer 12

Commonest functioning pituitary adenoma
Usually serum [prolactin] >5000 mU/L - significantly higher than normal, diagnosis will be very clear
Serum [prolactin] proportional to tumour size

Question 13

How will a patient with a prolactinoma present?

Answer 13

Menstrual disturbance (women)
Erectile dysfunction (men)
Reduced libido
Galactorrhoea (women)
Subfertility

Question 14

Why is galactorrhoea occurring in men very rare in cases of prolactinomas?

Answer 14

Galactorrhoea (lactation) very very rare in men, need oestrogen to prime/develop breasts to lactate

Question 15

What conditions will be caused by a prolactinoma?

Answer 15

Secondary hypogonadism - hypogonadotrophic hypogonadism

Question 16

What are the physiological causes of an elevated prolactin?

Answer 16

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

Question 17

What are the other pathological causes of an elevated prolactin, other than a prolactinoma?

Answer 17

Primary hypothyroidism (features low T3/T4 and high TSH, high TSH stimulates prolactin production - unknown mechanism)
Polycystic ovarian syndrome (also not fully understood, thought to be related to hormonal imbalance and hypothalamus dysfunction)
Chronic renal failure

Question 18

What are the iatrogenic causes of an elevated prolactin?

Answer 18

Antipsychotics
Selective serotonin re-uptake inhibitors
Anti-emetics
High dose oestrogen
Opiates

Question 19

What is the first step once a true pathological elevation in prolactin has been identified?

Answer 19

A pituitary MRI

Question 20

What is shown in this image?

Answer 20

Sellar microadenoma

Question 21

What is shown in this image?

Answer 21

Suprasellar macroadenoma - not yet reached, but is approaching, the optic chiasm

Question 22

What is the treatment for a prolactinoma?

Answer 22

First-line treatment is medical not surgical
Dopamine receptor agonists - cabergoline (bromocriptine)
Safe in pregnancy
Aim is to normalise serum prolactin & shrink prolactinoma
Microprolactinomas will need smaller doses than macroprolactinomas

Question 23

How do dopamine receptor agonists work?

Answer 23

Lactotrophs (including those in prolactinomas) have D2 receptors on their surfaces
Dopamine binds to these, which inhibits prolactin secretion
Dopamine receptor agonists also bind to these receptors, and so also stop prolactin secretion

Question 24

What conditions would a pituitary tumour secreting excess GH lead to?

Answer 24

Acromegaly(adults)/Gigantism(children)

Question 25

How does acromegaly present?

Answer 25

Often insidious presentation – mean time to diagnosis from onset of symptoms = 10y
Sweatiness
Headache
Coarsening of facial features: Macroglossia, prominent nose
Lage jaw - prognathism
Snoring/obstructive sleep apnoea
Hypertension
Impaired glucose tolerance/DM

Question 26

What is the mechanism of growth hormone action?

Answer 26

Acts directly on body tissues, stimulating growth
AND/OR
Acts on the liver, stimulating IGF-1 (and IGF-2) to be released, which acts directly on body tissues, stimulating growth

Question 27

How is acromegaly diagnosed?

Answer 27

GH pulsatile - random measurement unhelpful
Elevated serum IGF-1
Failed suppression of GH following oral glucose load

Question 28

Why dose acromegaly need to be treated in a timely manner?

Answer 28

Increased CVD risk in untreated acromegaly

Question 28

What is the first line treatment for acromegaly?

Answer 28

Surgery - trans-sphenoidal pituitary surgery
Aim to normalise serum GH and IGF-1

Question 29

What can be used in conjunction with surgery to treat acromegaly?

Answer 29

Can use medical treatment prior to surgery to shrink tumour or if surgical resection incomplete
Somatostatin analogues e.g. octreotide – ‘endocrine cyanide’
Dopamine agonists e.g. cabergoline (GH secreting pituitary tumours frequently express D2 receptors)

Question 30

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

Answer 30

Cushing’s syndrome = excess cortisol due to any underlying cause
Cushing’s disease = specifically a pituitary corticotroph adenoma secreting ACTH

Question 31

What investigations can be used to confirm Cushing’s disease?

Answer 31

Elevation of 24h urine free cortisol - increased cortisol in blood
Elevation of late night cortisol - salivary/blood test - loss of diurnal rhythm
Failure to suppress cortisol after oral dexamethasone

Question 32

What are the steps in confirming that a case of Cushing’s syndrome is actually Cushing’s disease?

Answer 32

Once confirmed hypercortisolism, measure ACTH
If ACTH high (ACTH dependent), pituitary MRI

Question 33

What are the ACTH dependent and independent causes of hypercortisolism?

Answer 33

ACTH dependent
-Cushing’s disease (pituitary corticotroph adenoma)
-Ectopic ACTH (eg lung cancer)
ACTH independent
-Taking steroids by mouth (common)
-Adrenal adenoma or carcinoma

Question 34

How does a non-functioning pituitary adenoma present?

Answer 34

Don’t secrete any specific hormone
Often present with visual disturbance (bitemporal hemianopia)
Can present with hypopituitarism
Serum prolactin can be raised (dopamine can’t travel down pituitary stalk from hypothalamus, so no inhibition of prolactin) - won’t be raised in most cases, but is possible
Any prolactin raise will be mild