Hyposecretion Of Anterior Pituitary Hormones Flashcards
What are the anterior pituitary hormones
1) gonadotrophins - FSH/LH
2) prolactin
3) growth hormone
4) TSH - thyroid stimulating hormone
5) ACTH - adrenocorticotropic hormone
What is the chain of command in the hypothalamo-adrenohypophysial axis?
Hypothalamus -> releasing/inhibiting hormones -> anterior pituitary -> anterior pituitary hormone -> gland -> glandular hormone
What is primary endocrine disease?
Problem is with the end gland itself.
What is secondary endocrine disease?
Problem is in the anterior pituitary
What is hypopituitarism?
Decreased production of ALL anterior pituitary hormones (panhypopituitarism)
OR of specific hormones
What are the two types of panhypopituitarism?
Congenital (rare) or acquired
What is congenital panhypopituitarism usually caused by?
Mutations of the transcription factor genes needed for normal anterior pituitary development - eg: PROP1 mutation
What hormone/s are people with congenital panhypopituitarism usually deficient in?
Growth hormone and at least one more anterior pituitary hormone
What do people with congenital panhypopituitarism present with?
Short stature
Because of lack of growth hormone
What shows up on the MRI of someone with congenital panhypopituitarism?
Hypoplastic anterior pituitary gland
What are the possible causes of acquired panhypopituitarism
Tumours Radiation Infection Traumatic brain injury Infiltrative disease Inflammatory Pituitary apoplexy Peri-partum infarction
What are the two types of tumours that can cause acquired panhypopituitarism
Hypothalamic - craniopharyngiomas (squash the pituitary, prevent releasing hormones from happening)
Pituitary - adenomas (benign tumours), metastases (from other cancers), cysts (that can squash the anterior pituitary)
Which pituitary hormone is most and least resistant to radiotherapy.
GH is most vulnerable. TSH relatively resistant
What is the autoimmune inflammation of the pituitary called?
Hypophysitis
What is the presentation of panhypopituitarism
Symptoms rely on deficient hormones
- Secondary hypogonadism
- reduced libido
- secondary amenorrhoea
- erectile dysfunction
- (cortisol deficiency - secondary hypoadrenalism)
- fatigue
- Secondary hypothyroidism
- fatigue
What happens in Sheehan’s syndrome
- specific to post partum hypopituitarism secondary to hypotension
- most common cause is post partum haemorrhage
- in pregnancy, pituitary gland gets bigger, because of lactotroph hyperplasia to make more prolactin.
- haemorrhage causes loss of blood supply - pituitary infarction
What is the presenartion of Sheehan’s syndrome
- lethargy, anorexia, weight loss - TSH, ACTH, GH deficiency
- failure of lactation - PRL deficiency
- failure to resume menses post delivery
(Post pituitary not affected)
What can pituitary apoplexy be precipitated by?
Anti-coagulants
What is pituitary apoplexy
Bleeding into or impaired blood supply of the pituitary gland - haemorrhage/infarction
What is the symptoms of pituitary apoplexy
Severe Sudden onset headache
Visual field defect - bitemporal hemianopia
Cavernous sinus - squash cranial nerves - Diplopia (double vision - IV, VI), ptosis (drooping of upper eyelid - III)
How do diagnose hypopituitarism biochemically?
1) BASAL plasma conc of pituitary or target endocrine gland hormones
Why could the interpretation be limited for blood analysis of hormones when testing for hypopituitarism?
> hormone profile for a lot of hormones varies throughout the days/weeks/years
(Eg - cortisol changes over a day, T4 - circulating half life of 6 days so if pt comes to A&E with apoplexy immediately T4 could still be high, FSH/LH - cyclical , GH/ACTH - pulsatile)
What is a stimulated (dynamic) pituitary function test?
ACTH and GH - Stress induced in the body by inducing hypoglycaemia (<2.2mM) by giving insulin. ACTH and GH (stress hormones) should increase in the blood to increase blood glucose.
TRH - stimulates TSH release
GnRH - stimulates FSH and LH release
TLDR: insulin, TRH, GnRH given to induce production of pituitary hormones
What is the HRT for ACTH and what do you monitor in the blood
Hydrocortisone given diurnally
Serum cortisol
