Hypopituitarism Flashcards
What are the 6 hormones released by the anterior pituitary gland?
- Prolactin
- Growth hormone (somatotrophin)
- Thyroid Stimulating Hormone (TSH)
- Luteinising Hormone (LH)
- Follicle Stimulating Hormone (FSH)
- Adrenocorticotrophic Hormone (ACTH)
What does prolactin stimulate?
Milk production
What does LH and FSH stimulate?
- Oestrogen
- Progesterone
What does TSH stimulate?
Triiodothyronine (T3) - active
Thyroxine (T4)
What does ACTH stimulate?
Cortisol release
What is the difference between primary and secondary pituitary gland failure?
Primary: failure of the gland itself
Secondary: no signals from the hypothalamus or the anterior pituitary
What is characteristic of primary hypothyroidism?
thyroid destruction
- T3 and T4 fall
- TSH increases (unmeasured but TRH would also be high)
What is characteristic of secondary hypothyroidism?
damaged thyrotrophs
- TSH falls
- T3 and T4 fall without TSH
What is characteristic of primary hypoadrenalism?
adrenal cortex destruction
- cortisol falls
- ACTH increases (CRH would be high)
What is a characteristic of secondary hypoadrenalism?
corticotroph damage
- ACTH falls
- Cortisol falls
What is characteristic of primary hypogonadism?
Destruction of testes (mumps) or ovaries (chemo)
- Testosterone / estrogen fall
- LH and FSH increase
What is characteristic of secondary hypogonadism?
damaged gonadotrophs
- LH and FSH fall (can’t be produced)
- Testosterone / estrogen fall
Causes of Hypopituitarism?
- Congenital (rare)
- Acquired
What are the congenital cause of hypopituitarism?
- Due to mutations of transcription factor genes needed for normal development (eg: PROP1 mutation)
- Deficient in GH and at least one more anterior pituitary hormone
- Short stature
- Hypoplastic anterior pituitary gland (MRI)
What are the acquired causes of hypopituitarism?
- tumours
- radiation
- infection
- traumatic brain injury
- pituitary brain surgery
- inflammation
- pituitary apoplexy (haemorrhage or infarction)
- peri-partum infection (Sheehan’s syndrome)
What can cause anterior and posterior pituitary gland dysfunction?
- inflammation (hypophysitis)
- surgery
What is the term for the total loss of anterior and posterior pituitary function?
Panhypopituitarism
Impact of radiotherapy on hypopituitarism?
- extent depends on the total dose of radiotherapy delivered to the hypothalamo-pituitary axis
- GH and gonadotrophins are most sensitive, and prolactin can increase after radiotherapy (loss of hypothalamic dopamine)
- risk persists up to 10years after radiotherapy (annual assessment necessary)
How does secondary hypopituitarism present?
- reduced libido
- secondary amenorrhoea
- erectile dysfunction
- reduced pubic hair
How does hypopituitarism with reduced ACTH present?
- fatigue
not a salt losing crisis (renin-angiotensin)
How does reduced TSH due to hypopituitarism present?
fatigue
How does reduced GH (hypopituitarism) present?
- reduced quality of life
ONLY IN CHILDREN - short stature
How does reduced prolactin present?
inability to breastfeed
What is Sheehan’s syndrome?
Post-partum hypopituitarism secondary to hypotension (post-partum haemorrhage, which can lead to a pituitary infarction)
What changes to the anterior pituitary occur during pregnancy?
Lactrotroph hyperplasia (It enlarges)
What are common symptoms of Sheehan’s syndrome?
TSH/ACTH/GH deficiency
- lethargy
- weight loss (anorexia possible)
PRL deficiency
- lactation failure
- failure to resume normal menses post-delivery
(posterior pituitary not normally affected)
What is pituitary apoplexy?
Intra-pituitary haemorrhage (rare: infarction)
What can cause pituitary apoplexy?
- can be caused by anti-coagulants
- can be first presentation of a pituitary adenoma
- can have a dramatic presentation with a current adenoma
What are the symptoms of a pituitary apoplexy?
- severe, sudden onset headache
- visual field defect (possible bitemporal hemianopia)
- Cavernous sinus involvement may lead to diplopia (IV, VI) and ptosis (III)
What is the nature of FSH/LH?
cyclical in women
What is the nature of GH/ACTH?
pulsatile
What is the nature of T4?
circulating t1/2 of 6 days
What can stimulate the release of GH and ACTH?
Insulin-induced hypoglycaemia
done in a dynamic pituitary function test
How to radiologically diagnose hypopituitarism?
Pituitary MRI (CT has poor differentiation) may reveal the pathology
How to treat a GH deficiency?
- confirm GH deficiency using a dynamic pituitary function test
- assess QoL
- Daily injection (Genotropin)
How to manage GH deficiency?
- Improvement in QoL
- Plasma IGF-1
How to treat a TSH deficiency?
- HRT using a once daily levothyroxine
- aim: fT4 above the middle of the reference range
How to treat a ACTH deficiency?
- replace cortisol NOT ACTH
- difficult to mimic the diurnal variation of cortisol
- use synthetic glucocorticoids:
- prednisolone (1 x daily)
- hydrocortisone (3 x daily)
What are people with an ACTH deficiency at risk of?
Adrenal crisis
How does an adrenal crisis present?
- dizziness
- hypotension
- vomiting
- weakness
- collapse
- death
What are sick day rules?
- steroid alert pendant/bracelet
- double steroid dose if fever/intercurrent illness
- if unable to take tablets, inject IM or straight to A&E
When are sick day rules necessary?
For patients that take replacement steroids
prednisolone or hydrocortisone
How to treat an LH/FSH deficiency in men (no fertility required)?
- testosterone replacement (topical or IM)
- plasma testosterone monitoring
(does not restore sperm production)
How to treat an LH/FSH deficiency in men (fertility required)
- induction of spermatogenesis by gonadotrophin injections
(may take 6-12 months) - best if secondary hypogonadism is developed post puberty
- testosterone measurements and semen analysis
How to treat an LH/FSH deficiency in women (no fertility required)?
- HRT (Oestrogen) by oral or topical means
- If intact uterus, progestogen to prevent endometrial hyperplasia
How to treat an LH/FSH deficiency in women (fertility required)?
induce ovulation using timed gonadotrophin injections (IVF)
Impact of ACTH deficiency on aldosterone?
No affect
