Hypopituitarism Flashcards
What are the 5 anterior pituitary hormones?
What regulates anterior pituitary hormone production? And where do they travel?
What do each of the anterior pituitary hormones make?
What glands can be affected if the anterior pituitary fails? What are the two different types of failure - explain?
Describe primary hypothyroidism
Describe secondary hypothyroidism
Describe primary hypoadrenalism
Describe secondary hypoadrenalism
Describe primary hypogonadism
Describe secondary hypogonadism
What are the congenital causes of hypopituitarism and how can it be seen?
What are the acquired causes of hypopituitarism and how can it be seen?
What is hypophysitis? Where does it affect?
Inflammation (hypophysitis) that can cause anterior and posterior pituitary dysfunction. Surgery can also dysfunction
What is panhypopituitarism?
Total loss of anterior & posterior pituitary function
How does radiotherapy induce hypopituitarism?
Pituitary and hypothalamus both sensitive to radiation
Radiotherapy direct to pituitary eg hormone producing pituitary tumour or indirect eg CNS tumour nearby
Higher total radiotherapy dose (Gy), higher risk of HPA axis damage
GH and gonadotrophins most sensitive
Risk persists up to 10y after radiotherapy, so annual assessment
What are presentations of secondary hypogonadism?
Lower FSH/LH
Reduced libido
Secondary amenorrhoea
Erectile dysfunction
Reduced pubic hair
What are presentations of secondary hypoadrenalism?
Lower ACTH
Cortisol loss - Fatigue
NB Not a salt losing crisis (renin-angiotensin)
What are presentations of secondary hypothyroidism?
Lower TSH
Fatigue
Long term - weight gain potentially
What are presentations of low GH?
Reduced quality of life
NB short stature only in children
What are presentations of lower PRL?
Inability to breastfeed
What is Sheehan’s syndrome?
Post-partum hypopituitarism secondary to hypotension (post partum haemorrhage - PPH)
More common in developing countries
Anterior pituitary enlarges in pregnancy (lactotroph hyperplasia)
PPH leads to pituitary infarction
What are presentations 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
What is the best radiological way to visualise the pituitary gland?
MRI
What is pituitary apoplexy?
Bleeding (haemorrhage) into the pituitary or loss of blood flow (infarction) to the pituitary
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 (blood thinners)
What are the presentations of pituitary apoplexy?
Severe sudden onset headache
Visual field defect – compressed optic chiasm, bitemporal hemianopia
Cavernous sinus involvement may lead to diplopia (IV, VI), ptosis (III)
What are biochemical diagnosis’s of hypopituitarism?
Caution in interpreting basal plasma hormone concentrations
Cortisol – what time of day?
T4 – circulating t1/2 6 days
FSH/LH – cyclical in women
GH/ACTH - pulsatile
What is a dynamic pituitary function test?
Used in the diagnosis of hypopituitarism
ACTH & GH = ‘stress’ hormones
Hypoglycaemia (<2.2mM) = ‘stress’
Insulin-induced hypoglycaemia stimulates
GH release
ACTH release (cortisol measured)
TRH stimulates TSH release
GnRH stimulates FSH & LH release
What can a pituitary MRI show?
Pituitary MRI (CT not so good at delineating pituitary gland)
May reveal specific pituitary pathology
eg haemorrhage (apoplexy), adenoma
Empty sella – thin rim of pituitary tissue
How hormone can you not give if someone has hypopituitarism?
Prolactin
How can GH deficiency be treated?
NICE guidance
Confirm GH deficiency on dynamic pituitary function test
Assess Quality of Life (QoL) using specific questionnaire
Daily injection
Measure response by :
-improvement in QoL
-plasma IGF-1
How can TSH deficiency be treated?
Straightforward
Replace with once daily levothyroxine
Don’t forget, TSH will be low, so you can’t use this to adjust dose as you do in primary hypothyroidism
Aim for a fT4 above the middle of the reference range
How can ACTH deficiency be treated?
Replace cortisol rather than ACTH
Difficult to mimic diurnal variation of cortisol
Two main options in the UK using synthetic glucocorticoids
-Prednisolone once daily AM eg 3mg
-Hydrocortisone three times per day eg 10mg/5mg/5mg
What are those with adrenal failure at risk of? How is this presented
Patients with primary adrenal failure (Addison’s) or secondary adrenal failure (ACTH deficiency) at risk of ‘adrenal crisis’ triggered by intercurrent illness
Adrenal crisis features – dizziness, hypotension, vomiting, weakness, can result in collapse and death
What are sick day rules?
Patients who take replacement steroid eg prednisolone, hydrocortisone must be told sick day rules
-Steroid alert pendant/bracelet
-Double steroid dose (glucocorticoid not mineralocorticoid) if fever/intercurrent illness
-Unable to take tablets (eg vomiting), inject IM or come straight to A & E
How can FSH/LH deficiency be treated if fertility is not required in men?
Replace testosterone – topical or intramuscular most popular
Measure plasma testosterone
Replacing testosterone does not restore sperm production (this is dependent on FSH)
How can FSH/LH deficiency be treated if fertility is required in men?
Induction of spermatogenesis by gonadotropin injections
Best response if secondary hypogonadism has developed after puberty
Measure testosterone and semen analysis
Sperm production may take 6-12 months
How can FSH/LH deficiency be treated if fertility is not required in women?
Replace oestrogen
Oral or topical
Will need additional progestogen if intact uterus to prevent endometrial hyperplasia
How can FSH/LH deficiency be treated if fertility is required in women?
Can induce ovulation by carefully timed gonadotropin injections (IVF)
