ENDOCRINOLOGY - HYPERPITUITARISM Flashcards
What causes hyperpituitarism?
Pituitary adenoma - most often the cause
Ectopic production of pituitary hormones
Carcinoma
Whats the most common cause of hyperpituitarism?
Pituitary adenoma
What is a pituitary adenoma?
A benign tumour in the anterior pituitary that arises from a specific cell type
How are pituitary adenomas classified?
They are classified by size:
<1cm micro adenomas
>1cm they are macroadenomas
They are also classified as functional or non-functional.
Macroadenomas are more likely to compress surrounding structures. What structures may they compress and what are the consequences of this?
Meninges - headache
Optic nerve - bitemporal hemianopia
May compress other pituitary cells and interfere with their ability to make hormones
Whats the difference between a functional and non-functional adenoma?
Functional adenomas secrete hormones
Non-functional adenomas do not
Whats the most common type of pituitary adenoma?
Prolactinoma - tumour arising from lactotrophs
What are the different types of pituitary adenoma?
Prolactinoma
Somatotrope derived adenoma
Coticotroph derives adenoma
Thyrotroph derived adenoma
Gonadotropin derives adenoma
Whats the effect of somatotrope derived adenomas?
Gigantism and acromegaly
Whats the effect of a corticotroph-derived adenoma?
It’s ACTH secreting so can cause Cushing disease
Whats the effect of a Thyrotroph derived adenoma?
Secretes excess TSH which can cause hyperthyroidism signs
Whats the effects of gonadotropin derived adenomas?
They are often clinically silent and non-functional but may cause hypogonadism
May also cause compression signs
Whats the most frequent type of non-functional pituitary tumour?
Gonadotropin derived adenomas
What are the potential complications of pituitary adenomas?
Mass effect
Pituitary apoplexy
Sella turcica erosion
Hormone-related diseases e.g. Cushing syndrome
How do we diagnose pituitary adenomas?
Measure pituitary hormone levels
Gadolinium-enhanced MRI to image pituitary gland
How do you treat non-functional pituitary adenomas?
Surgical removal but only if large enough to cause sympotms
What usually inhibits and stimulates prolactin release?
Dopamine is a prolactin inhibiting factor
Thyrotropin releasing hormone stimulates its release
What can cause hyperprolactinemia?
Physiological e.g. pregnancy or lactation
Prolactinoma
Hypothyroidism - as TRH stimulates its release
Medications e.g dopamine antagonists - most common cause
Damage or compression to hypothalamic-pituitary stalk
What medications can cause hyperprolactinemia?
Dopamine antagonists e.g. metoclopramide, domperidone, phenothiazines and haloperidol
Oestrogens
Why can damage to the hypothalamic-pituitary stalk cause hyperprolactinemia?
As dopamine can’t reach the lactotroph cells
What are the symptoms of hyperprolactinemia?
Galactorrhoea, amenorrhoea and painful breasts in women
Gynaecomastia, erectile dysfunction, infertility, impotence or decreased libido in men
Compression symptoms if caused by prolactinoma
What is a prolactinoma?
A benign tumour of the lactotroph cells in the pituitary gland that secretes excess prolactin
What are micro and macroprolactinomas?
Microprolactinomas are <10mm and macroprolactinomas are >10mm
Why do prolactinomas decrease oestrogen and testosterone?
As excess prolactin inhibits GnRH release which causes less FSH and LH
