Pituitary hormone regulation and presentation of pituitary disease Flashcards
What makes up the thyroid axis?
Hypothalamus
Pituitary
Thyroid
Which hormone does the hypothalamus produce to later stimulate the thyroid?
TRH
Which hormone does the pituitary release that acts on the thyroid?
TSH
Which hormones produced by the thyroid has a negative feedback effect on the thyroid axis?
T4 and T3
How does TRH travel from the hypothalamus to the pituitary?
Through portal circulation
How does TSH travel from the pituitary to the thyroid?
Through systemic circulation
What makes up the pituitary gonadal axis?
Hypothalamus
Pituitary
Gonads (testes/ovaries)
What makes up the HPA axis?
Hypothalamus
Pituitary
Adrenal gland
What hormone does the pituitary release that acts on the adrenal glands?
ACTH
What hormone do the adrenal glands produce that act on the pituitary?
Cortisol
What makes up the GH/ IGF-I axis?
Hypothalamus
Pituitary
Liver
What hormone does the hypothalamus produce that acts on the pituitary in the GH/ IGF-I axis?
GHRH
What hormone does the pituitary release in the GH/ IGF-I axis?
GH
What does GH act on?
The liver
What hormone does the liver produce?
IGF-I (insulin like growth factor)
What does IGF-I act on?
Has a negative feedback effect on the hypothalamus
What hormone produced by the hypothalamus has a negative feedback effect on the GH/ IGF-I axis?
Somatostatin
Which hormones produced by the hypothalamus regulate GH?
GHRH and somatostatin
Which hormone produced by the hypothalamus regulates LH and FSH?
GnRH
Which hormone produced by the hypothalamus regulates ACTH?
CRH
Which hormone produced by the hypothalamus regulates TSH?
TRH
Which hormone produced by the hypothalamus regulates prolactin?
Dopamine
What are some diseases of the pituitary?
- Benign pituitary adenoma
- Craniopharygioma
- Trauma
- Apoplexy / Sheehans
- Sarcoid / TB
What are 3 vital points of presentation for diagnosing pituitary tumours?
- Pressure on local structure e.g. optic nerves
- Bitemporal hemianopia - Pressure on normal pituitary
- hypopituitarism - Functioning tumour
- Prolactinoma
- Acromegaly
- Cushing’s disease
What are features of prolactinomas?
- More common in women
- Present with galactorrhoea/ amenorrhoea/ infertility
- Loss of libido
- Visual field defect
- Treatment dopamine agonist eg. Cabergoline or bromocriptine
What would you want to investigate in someone with a pituitary tumour?
- Is it pressing on optic chiasm?
- Are they hypopituitary?
- Do they have a functioning tumour?
