Pituitary Tumors

Question 1

What do pituitary tumors of somatotrophs cause?

Answer 1

Acromeglay

Question 2

What do pituitary tumors of lactotrophs cause?

Answer 2

Prolactinoma

Question 3

What do pituitary tumors of thyrotrophs cause?

Answer 3

TSHoma

Question 4

What do pituitary tumors of gonadotrophs cause?

Answer 4

Gonadotrophinoma

Question 5

What do pituitary tumors of corticotrophs cause?

Answer 5

Cushings disease (corticotrophadenoma)

Question 6

How are pituitary tumors classified radiologically?

Answer 6

Size, micro or macrodenoma (less or more than 1cm), sellar or suprasellar, invading optic chiasm or not, invading cavernous sinus or not

Question 7

How are pituitary tumors classified functionally?

Answer 7

Is there excess secretion of a specific pituitary hormone or not (non functioning adenoma)?

Question 8

How are pituitary tumors classified as benign or malignant?

Answer 8

Mitotic index measured, benign if <3%

NOTE: can have benign histology but display malignant behaviour

Question 9

Where is the cavernous sinus found?

Answer 9

The sides of the pituitary gland

Question 10

What is special about pituitary tumors that invade the cavernous sinus?

Answer 10

They are non operable- many important structures are present in cavernous sinus eg cranial nerves and carotid artery

Question 11

Are most pituitary tumors functioning or not?

Answer 11

Non functioning and benign- not carcinomas

Question 12

Are most pituitary tumors benign or malignant?

Answer 12

Benign

Question 13

Describe the hormonal axis in hyperprolactinaemia

Answer 13

Excess prolactin
Binds to kisspeptin neurons in hypothalamus
Less kisspeptin released
Reduced release of GnRH from hypothalamus
Reduced release of LH/FSH from anterior pituitary
Reduced oestrogen (women) and testosterone (men)

Question 14

How is GnRH released in the body?

Answer 14

Pulsatile in puberty

Question 15

What are the physiological effects of hyperprolactinaemia?

Answer 15

Oligo-amenorrhea, low libido, infertility, osteoporosis

Question 16

Why does hyperprolactinaemia cause osteoporosis long term?

Answer 16

Bones require sex hormones (oestrogen and testosterone) for strength

Question 17

What is the most common pituitary adenoma?

Answer 17

Prolactinoma

Question 18

How does size of prolactinoma effect prolactin levels?

Answer 18

Serum prolactin is proportional to tumor size, bigger tumor=more prolactin

Question 19

How do prolactinomas present?

Answer 19

Menstrual disturbance, erectile dysfunction, reduced libido, galactorrhea (milk production from breast), subfertility (no sperm production or egg release)

Question 20

What are causes of elevated prolactin other than prolactinomas?

Answer 20

Physiological= pregnancy/breastfeeding, stress (venepuncture, exercise, seizure), nipple stimulation
Pathological= primary hypothyroidism, PCOS, chronic renal failure
Latrogenic= antipsychotics, SSRIs, high dose oestrogen, opiates

Question 21

How do we confirm elevated serum prolactin isnt a false positive?

Answer 21

If there is mild elevation, check that they have at least one symptom thats expected if not, consider:

Macroprolactin= instead of circulating as singular molecules, the prolactin sticks together in big clumps

Stress of venepuncture= exclude this by a cannulated prolactin series

Question 22

How are prolactinomas treated?

Answer 22

Medical not surgical

Use a dopamine receptor agonist eg cabergoline to normalise serum prolactin and shrink tumors

Question 23

How do dopamine receptor agonists work?

Answer 23

Dopamine binds to D2 receptors on lactotrophs which prevents prolactin release, the agonist does the same

Question 24

What happens to growth plates when you grow up?

Answer 24

They fuse so you stop growing

Question 25

What are presentations of acromeglay?

Answer 25

``` Sweatiness Headache Macroglossia Prominent nose Large jaw Snoring/sleep apnoea Larger hand and feet ```

Question 26

Describe the mechanisms of GH

Answer 26

Body tissues metabolic actions leads to growth and development Increases IGF-1

Question 27

How is acromegaly diagnosed?

Answer 27

Check if IGF-1 is high | Give them a 75g drink of glucose, in acromegaly GH will go up for normal people it should go down

Question 28

What is the main risk for those with acromegaly?

Answer 28

Increased cardiovascular risk

Question 29

What happens when someone has excess cortisol?

Answer 29

Cushings syndrome

Question 30

What are the causes of Cushings?

Answer 30

``` ACTH dependant or independant: Too many oral steroid Adenoma of corticotrophs Cancer of lung= too much ACTH Tumor of adrenal gland ```

Question 31

How do we investigate Cushings?

Answer 31

``` Observe urine cortisol for 24 hrs (will be constantly high in Cushings) Elevation of late night cortisol (via blood test) Give dexomethasone (cortisol will still be high in Cushings) ```

Question 32

How do non functioning pituitary tumors commonly present?

Answer 32

Visual disturbance eg bitemporal hemianopia

Question 33

What can non functioning tumors surprisingly present with?

Answer 33

Hypopituitarism- stops all hormones being secreted

Question 34

What happens to prolactin in non functioning tumors and why?

Answer 34

Cant be raised as dopamine cant travel down pituitary stalk from hypothalamus

Question 35

How are non functioning tumors treated and when?

Answer 35

Trans sphenoidal surgery but only if close to optic chiasm to prevent visual disturbance

Question 36

What medicine is given for acromegaly?

Answer 36

Octreotide- GH agonist