HYPOPITUITARISM Flashcards
Name all anterior pituitary hormones and their respective effects
prolactin - milk production
growth hormone - growth in tissues and IGF-1/2 in liver
TSH - production of T3/4 in thyroid
ACTH - cortisol production in zona fasciculata
LH/FSH - production of testosterone/oestrogen/progesterone by gonads
What is the difference between primary and secondary disease
primary - problem with the gland itself
secondary - problem with hypothalamus or pituitary
Describe primary hypothyroidism vs secondary hypothyroidism and examples
primary - autoimmune destruction against thyroid gland. T3/4 decrease, TSH increase
secondary - pituitary tumour damaging thyrotrophs. Low TSH, low T3/4
Describe primary hypoadrenalism vs secondary hypoadrenalism and examples
primary - autoimmune destruction of adrenal cortex (addison’s). Cortisol decrease, ACTH increase
secondary - pituitary tumour damaging adrenotrophs. Cortisol decrease, ACTH decrease
Describe primary hypogonadism vs secondary hypogonadism and examples
primary - destruction of testes (mumps) or ovaries (chemotherapy). Testosterone/oestrogen decrease, LH/FSH increase
secondary - pituitary tumour damaging gonadotrophs. Testosterone/oestrogen decrease, LH/FSH decrease
What usually causes congenital hypopituitarism
Mutations of transcription factor genes e.g. (PROP1)
Outline features of congenital hypopituitarism
Low GH and at least 1 more anterior pituitary hormone
Short stature (low GH)
Hypoplastic anterior pituitary on MRI
List causes of acquired hypopituitarism
tumours e.g. adenomas, radiation, infection, traumatic brain injury, inflammation, pituitary apoplexy (haemorrhage or infarction), Sheehan’s syndrome, pituitary surgery
What is total loss of anterior and posterior pituitary function called?
Panhypopituitarism
Example of direct and indirect radiotherapy to pituitary
acromegaly (direct), nasopharyngeal carcinoma (indirect)
What does radiotherapy of pituitary especially effect?
GH and gonadotrophins most sensitive
Prolactin can increase after radiotherapy because of loss of hypothalamic dopamine
How long does the risk of radiotherapy persist up to?
10 years so need to do annual checkups
What is Sheehan’s syndrome?
After giving birth, postpartum haemorrhage may occur causing hypotension/hypovolemia in mother. This causes ischaemic necrosis of pituitary and hypopituitarism of mother
Why is the posterior pituitary usually not affected in Sheehan’s syndrome?
Posterior pituitary is neural and doesn’t depend on blood supply
List symptoms of Sheehan’s syndrome
Lethargy, anorexia, weight loss
Failure of lactation
Failure to resume menses (periods) post-delivery
What is pituitary apoplexy?
Intra-pituitary haemorrhage or infarction often with dramatic presentations in a patient who has an adenoma. Could be first sign of adenoma. Can be caused by anti-coagulants.
What are some symptoms of pituitary apoplexy?
Severe sudden onset of headache
Defect in visual field (compressed optic chiasm)
if cavernous sinus involved - can cause diplopia (CN IV, VI) and ptosis (CN III)
The blood can cause compression of the surroubnding structures
What should you be aware of when measuring cortisol, T4, LH/FSH and GH/ACTH
Cortisol is diurnal so measure in morning
T4 has a half time of 6 days
LH/FSH is cyclical in women and depends on when in the menstrual cycle it is measured
GH/ACTH are pulsatile
What is the method of measuring ACTH and GH?
Insulin-induced hypoglycaemia in patient stimulates GH and ACTH release since they are stress hormones. Cortisol is measured instead of ACTH.
What is the method of measuring TSH and FSH/LH?
Inject TRH or GnRH to stimulate release and measure
What is the best way if radiologically diagnosing hypopituitarism?
MRI
What is it called when no/little pituitary tissue is seen in an MRI?
Empty sella
Which anterior pituitary hormone deficiency cannot ben treated?
Prolactin
What is the treatment of GH deficiency in adults?
Assess quality of life in patients using questionnaire.
If low QoL give daily injections of GH and measure the progress by improvement in QoL and plasma IGF-1
What is the treatment of TSH deficiency?
One daily tablet of levothyroxine and aim for a free T4 above the middle of the reference range
What is the treatment of ACTH deficiency?
Replace cortisol rather than ACTH.
Give patient synthetic glucocorticoids:
- Prednisolone once daily AM or
- Hydrocortisone 3 times per day
This mimics the diurnal variation of cortisol
What are patient’s with ACTH deficiency/Addison’s primary adrenal failure at risk of?
Adrenal crisis which can be triggered by an intercurrent illness e.g. UTI
What are the sick day rules and who are they told to?
patients who take replacement steroids
steroid alert pendant/bracelet
double glucocorticoid does if fever /intercurrent illness
if unable to take tablets e.g. vomiting come to A&E or inject IM
What is the treatment of FSH/LH deficiency in men where fertility is not required?
Replace testosterone with topical gel or intramuscularly. Measure plasma testosterone
(testosterone does not restore sperm production)
What is the treatment of FSH/LH deficiency in men where fertility is required?
Inject gonadotrophin to induce spermatogenesis. Best response if the secondary hypogonadism has developed after puberty.
Measure testosterone and semen analysis.
How long does sperm production take after treatment of FSH/LH in men?
6-12 months
What is the treatment of FSH/LH deficiency in women where fertility is not required?
Replace oestrogen with oral or topical method\
If uterus intact administer additional progestogen to prevent endometrial hyperplasia
What is the treatment of FSH/LH deficiency in women where fertility is required?
Induce ovulation by carefully timed gonadotrophin injections (IVF)
