Hypopituitarism Flashcards
What is the function of the hypothalamus in the
endocrine system?
Regulating the release of hormones from the pituitary gland - control other endocrine glands
What is the difference between primary and
secondary hypopituitarism?
1° Hypopit - dysfunction of pituitary gland
2° Hypopit - dysfunction of the hypothalamus
What is Sheehan’s syndrome?
Condition where pituitary gland is damaged due to severe bleeding in childbirth
What is the function of growth hormone?
aka somatotrophin
stimulates growth and cell reproduction
What is the function of TSH?
aka thyrotrophin
stimulates thyroid to produce hormones
What is the function of LH and
FSH?
regulates the reproductive system
What is the function of ACTH?
aka corticotrophin
stimulates release of cortisol, hormone that helps with stress
What is the hypothalamo-pituitary portal system?
Specialised network of blood vessels connecting hypothalamus and pituitary, allows transport of hormones
What is the function of the
hypothalamo-pituitary portal system?
Stimulatory/ inhibitory factors travel in portal circulation to anterior pituitary.
Anterior pituitary hormones
GH, ACTH, LH, TSH, FSH, Prolactin
What are the causes of
anterior pituitary failure?
1° disease - gland itself fails
2° disease - no signals from hypothalamus or anterior pituitary
What are the clinical features
of primary hypothyroidism?
T3 and T4 levels fall,
while TSH levels increase.
What are the clinical features
of secondary hypothyroidism?
TSH levels fall due to
pituitary tumor damaging thyrotrophs, leading to a
decrease in T3 and T4 levels.
Treated with levothyroxine, dose adj to fT4
Primary hypoadrenalism
destruction of adrenal cortex (e.g. autoimmune)
cortisol falls, ACTH rises
Secondary hypoadrenalism
pituitary tumour damaging corticotrophs
Can’t make ACTH
ACTH falls, cortisol falls
treated with glucocorticoid replacement (prednisolone/hydrocortisone)
Primary hypogonadism
destruction of testes (mumps) or ovaries (chemotherapy)
Testosterone/oestrogen fall, LH & FSH increase (we don’t measure GnRH but that
would also be high)
Secondary hypogonadism
pituitary tumour damaging gonadotrophs
LH/FSH fall, Testosterone/oestrogen fall
management depends on whether restoration of fertility is needed
What are the causes of congenital hypopituitarism?
usually due to
mutations of transcription factor genes needed for
normal anterior pituitary development.
What are the 8 acquired causes of hypopituitarism?
TTRIIPSS: tumour, trauma, radiotherapy, infection, inflammation (hypophysitis), pituitary apoplexy, surgery, sheehan’s syndrome
What are the clinical features of congenital
hypopituitarism?
short stature and hypoplastic
(underdeveloped) anterior pituitary gland on MRI.
What are the clinical features of acquired
hypopituitarism?
may include fatigue,
weight loss, decreased libido, infertility, menstrual
irregularities, and cold intolerance.
What is panhypopituitarism?
Total loss of anterior and posterior pituitary function
What may cause posterior pituitary dysfunction?
Certain processes, especially inflammation (hypophysitis) or surgery.
What is radiotherapy-induced
hypopituitarism?
pituitary and hypothalamus are both sensitive to radiation.
prod pituitary/CNS tumour
The higher the radiotherapy dose (Gy), the higher the risk of HPA axis damage
GH and gonadotrophins most sensitive
Risk persists up to 10yrs post radiotherapy .: annual assessment needed
Name a cause of anterior
pituitary damage (hypopituitarism).
radiotherapy, inflammation, or
surgery
What are the clinical features
of hypopituitarism related to FSH/LH?
Reduced libido, secondary amenorrhea, erectile
dysfunction, and reduced pubic hair
What are the clinical features
of hypopituitarism related to ACTH?
Fatigue
Not a salt-losing crisis
(renin-angiotensin).
What are the clinical features
of hypopituitarism related to TSH?
Fatigue
What are the clinical features
of hypopituitarism related to GH?
Reduced quality of life and short stature (only in
children)
What are the clinical features
of hypopituitarism related to PRL?
Inability to breastfeed
Sheehan’s syndrome?
Post partum bleeding -> hypotension -> pituitary infarction
lactotroph hyperplasia in pregnancy (larger anterior pituitary)
What are the clinical features of Sheehan’s
syndrome?
- lethargy, anorexia, weight loss (TSH, ACTH,GH deficiency)
- failure of lactation (PRL deficiency)
- amenorrhea post delivery (LH/FSH)
What is the treatment for Sheehan’s syndrome?
HRT
What is the best radiological way to visualize the
pituitary gland?
MRI
What is pituitary apoplexy?
Haemorrhage into pituitary gland
sometimes due to blood thinners
What are the clinical features of pituitary apoplexy?
severe sudden onset headache
bitemporal hemianopia
diplopia (double vision)
ptosis (droopy eyelid)
visual field defect
cavernous sinus involvement
What is the treatment for pituitary apoplexy?
HRT and sometimes surgery
Why does Sheehan’s syndrome not affect posterior pituitary function?
Blood supply for posterior pituitary is from a different pathway (neuronal), is not affected
High intravascular blood pressure .: protected against hypotension
What are 3 of the other potential differential diagnoses for someone you suspect has Sheehan’s syndrome?
Anaemia (blood loss), Post-natal depression, Primary hypothyroidism
What are 7 questions you would ask someone who you suspect has Sheehan’s syndrome?
history of depression, breastfeeding specifics, weight loss, visual problems, previous thyroid problems, family history, medication history (dopamine antagonists)
What should be considered as a reason for pituitary apoplexy?
pituitary adenoma
Why is caution needed when interpreting basal
plasma hormone concentrations for
hypopituitarism?
Cortisol levels vary depending on the time of day,
T4 has a circulating half-life of 6 days,
FSH/LH are
cyclical in women,
GH/ACTH are pulsatile.
What is the dynamic pituitary function test for
diagnosing hypopituitarism?
ACTH and GH are stimulated by hypoglycaemia, measure IGF1.
What 3 specific things may be found in hypopituitarism MRI?
Haemorrhage, Adenoma, Empty Sella Turcica
How would you treat GH deficiency and why is it complicated?
Daily injection of GH, measure QoL and plasma IGF-1 // not essential - depends on QoL and expense
How would you treat TSH deficiency?
Levothyroxine (T4), treat above middle ref range
How would you treat ACTH?
Corticosteroids: Prednisolone (once daily - high cortisol and drops) or Hydrocortisone (3x daily - spikes of cortisol - short half life)
What do ACTH steroid users report as a side effect?
Very low mood in the morning (low cortisol - tablet wears off)
What is the risk of adrenal crisis for patients with
primary or secondary adrenal failure?
Patients with primary or secondary adrenal failure
are at risk of adrenal crisis triggered by intercurrent
illness.
What risk do ACTH steroid users have to be aware of?
Adrenal Crisis, aka sick day rules: wear steroid user pendant, double dose of glucocorticoid, go to A&E
What are the features of adrenal crisis?
Adrenal crisis features include dizziness, hypotension, vomiting, weakness, and can result in
collapse and death.
How would you treat FSH/LH deficiency in men?
If fertility is not an issue - testosterone //
If fertility is important - gonadotrophin injections to induce spermatogenesis (6-12 months)
Does replacing testosterone restore sperm
production?
No, as this is dependent on FSH.
How would you treat FSH/LH deficiency in women?
If fertility is not important, oral oestrogen medication (HRT) //
If fertility is important then gonadotrophin injections aka IVF
What two hormones are in HRT?
Oestrogen and Progesterone (to avoid endometrial hyperplasia secondary to oestrogen dose)
Why is HRT given instead of oral contraceptives?
Oral contraceptives is a high unregulated oestrogen dose, HRT is a physiological level dose and has progesterone to avoid endometrial hyperplasia
