Hyposecretion Of Anterior Pituitary Hormones Flashcards
Anterior pituitary hormones
FSH/LH (gonadotrophins) Prolactin GH TSH ACTH
Anterior pituitary action
Hypothalamus makes releasing/inhibiting hormone
Anterior pituitary hormone releases hormone
Endocrine gland (thyroid, gonads, adrenal cortex) produces primary hormone
Disorder in the endocrine gland results in
Primary endocrine gland disease
Disorder in the anterior pituitary results in
Secondary endocrine gland disease
Panhypopituitarism
Decreased production of all anterior pituitary hormones
NOTE: congenital is rare, mostly acquired
Congenital panhypopituitarism
Rare
Usually due to mutations of transcription factor genes needed for normal anterior pituitary development
- e.g. PROP1 mutation
Deficient in GH and at least 1 more anterior pituitary hormone
Short stature
Hypoplastic anterior pituitary gland on MRI
Acquired panhypopituitarism (causes)
Tumours
- hypothalamic - craniopharyngiomas
- pituitary - adenomas, metastases, cysts
Radiation
- hypothalamic/pituitary damage
- GH most vulnerable, TSH relatively resistant
Infection (e.g. meningitis)
Traumatic brain injury
Infiltrative disease - often involves pituitary stalk (e.g. neurosarcoidosis)
Inflammatory (hypophysitis)
Pituitary apoplexy
- haemorrhage (or less commonly infarction)
Peri-partum infarction (SHeehan’s syndrome)
Presentation of panhypopituitarism
Occassionally called Simmond’s disease
Symptoms due to deficient hormones:
FSH/LH:
- secondary hypogonadism
- reduced libido
- secondary amenorrhoea
- erectile dysfunction
ACTH:
- secondary hypoadrenalism (cortisoldeficiency)
- fatigue
TSH:
- secondary hypothyroidism
- fatigueSheehan’s syndrome
Specifically describes post-partum hypopituitarism secondary to hypotension (post partum haemorrhage - PPH)
Less common in developed countries
Anterior pituitary enlarges in pregnancy (lactotroph hyperplasia - to make lots of prolactin )
PPH leads to pituitary infarction
Slide 10 [pic]
Presentation of Sheehan’s syndrome
Lethargy, anorexia, weight loss - TSH/ACTH/(GH) deficiency
Failure of lactation - PRL deficiency
Failure to resume menses post-delivery
Posterior pituitary usually not affected
Pituitary apoplexy
Intra-pituitary haemorrhage or (less commonly) infarction
Often dramatic presentation in patients with pre-existing pituitary tumours (adenomas)
May be first presentation of a pituitary adenoma
Can be precipitated by anti-coagulants
Bleed into pituitary gland:
- severe sudden onset headache
- visual field defect - compressed optic chiasm, bitemporal hemianopia
Cavernous sinus involvement may lead to diplopia (IV, VI), ptosis (III)
Slide 13 [pic]
Diagnosis of hypopituitarism - biochemical
- Basal plasma concentrations of pituitary or target endocrine gland hormones
- interpretation may be limited
- undetectable cortisol - what time of day?
- T4 - circulating t(1/2) 6 days
- FSH/LH - cyclical
- GH/ACTH - pulsatile
- Stimulated (‘dynamic’) pituitary function tests
- ACTH and GH = ‘stress’ hormones
- hypoglycaemia (<2.2mM) = stress
- inuslin-induced hypoglycamia stimulates:
GH release
ACTH release (cortisol measured) - TRH stimulates TSH release
- GnRH stimulates FSH and LH release
Hypopituitarism diagnosis - radiological
Pituitary MRI
May reveal specific pituitary pathology e.g. haemorrhage (apoplexy), adenoma
Empty sella - thin rim of pituitary tissue
Slide 17 [pic]
Hormone replacement therapy in hypopituitarism
Slide 18 [pic]
Growth hormone (somatotrophin) deficiency
In children = short stature (=2 SDs < mean height for children of that age and sex)
In adults = effects less clear
