Hypopituitarism Flashcards
What does hypo mean?
Under active
What are the anterior pituitary hormones?
GH Prolactin TSH LH/FSH ACTH
Summarise the hypothalmo-pituiraty portal system
Hypothalamic released or inhibitory factors travel in the portal circulation the anterior pituitary to regulate anterior pituitary hormone productions
What is primary failure of a gland?
When the gland itself is not working
What is secondary failure of a gland?
When there is no signal to the gland and it cannot be told what to do
What is primary hypothyroidism?
e.g. Autoimmune destruction of thyroid gland
T3 and T4 fall
TSH increases
TRH would also be high
What is secondary hypothyroidism?
E.g. pituitary tumour damagingly thyrotrophs
Can’t make TSH
TSH falls
T3 and T4 fall as no TSH
The signal is the problem
What is cortisol regulated by?
ACTH
What is aldosterone regulated by?
Renin-angiotensin
What is primary hypoadrenalism?
e.g. Destruction of adrenal cortex
Cortisol falls
ACTH increases
Addison’s
What is secondary hypoadrenalism?
e.g. Pituitary tumour damaging corticotrophs
Cannot make ACTh
ACTH falls, cortisol falls
No hyperpigmentation like in additions because low ACTH
What is primary hypogonadism?
E.g. destruction of testes (mumps) or ovaries (chemo)
Testosterone or Oestrogen falls
LH and FSH increase
GnRH would also be high (don’t measure)
What is secondary hypogonadism?
E.g. pituitary tumour damaging gonadotrophs
Can’t make LH/FSH
LH/FSH fall
Testosterone and oestrogen fall
Why might the anterior pituitary not be working?
Congenital
Acquired
What are the congenital causes of hypopituitarism?.
Rare
Usually due to mutations of transcription factor genes needed for normal anterior pituitary development
e.g. PROP1 mutation
What are the acquired causes of hypopituitarism?
Tumours Radiation Infection e.g. meningitis Traumatic brain injury Pituitary surgrey Inflammatory (hypophysitis)
Pituitary apoplexy - haemorrhage (less commonly infarction)
Peri-partum infarction (Sheehan’s syndrom)
Which axis’ would hypopituitarism affect?
Can use one, several or all axis
What processes also damage the posterior pituitary?
Inflammation
What is pan-hypopituitarism?
When it affects the anterior and posterior pituitary
How can radiotherapy damage the pituitary?
Direct e.g acromegaly
Indirect e.g. nasopharyngeal carcinoma
What is most sensitive to radiation damage?
GH and Gonadotrophin
What can increase after radiotherapy?
Prolactin
Are the affects of radiant seen in the long-term?
Yes, up to 10 years after treatment
What is an example of primary ovarian failure?
The Menopause
Ovaries stop working
Oestrogen falls
FSH/LH goes up
How would low FSH/LH present?
Reduced libido
Secondary amenorrhoea
Erectile dysfunction
Reduced pubic hair
How would low ACTH present?
Fatigue
Weight loss
(No salt loosing crisis like Addisons)
How would low TSH present?
Fatigue
How would low GH present?
Reduced quality of life
Short stature only in children
How would low prolactin present?
Inability to breastfeed
What is Sheehan’s syndrome?
Post-partum hypipituitarism secondary to hypotension (post partum haemorrhage)
More common in developing countries
Anterior pituitary enlarges in pregnancy (lactotroph hyperplasia)
PPH leads to pituitary infarction due to lack of blood supply
Pituitary cells no longer produce hormones
What are the symptoms of Sheehan’s syndrome?
Lethargy Anorexia Weight Loss TSH/ACTH/GH deficiency Failure of lactation (PRL deficiency) Failure to resume messes post-delivery Posterior pituitary usually not affected
What is the best way to visualise the pituitary?
MRI
What is pituitary apoplexy?
Intra-pituitary haemorrhage (less commonly infarction)
Often dramatic presentation in patients with pre-existing pituitary adenomas
May be first presentation of a pituitary adenoma
Can be precipitated by anti-coagulants
What are the symptoms of pituitary apoplexy?
Severe sudden onset headaches
Visual field defect- compressed optic chiasm (bitemporal hemianopia)
Cavernous sinus involvement may lead to diplopia - double vision (IV, VI), ptosis - droopy eyelid (III)
Compromising cranial nerves that run through the cavernous sinus
Why is hypopituitarism diagnosis difficult?
Cortisol - differs during the day
T4 - circulating half life of 6 days
FSH/LH - cyclical in women
GH/ACTH - pulsatile
How is hypopituitarism diagnosed?
Dynamic pituitary function
Stress the body with hypoglycaemia by giving insulin
ACTH and GH are ‘stress hormones’ and are released
We can give TRH which stimulates TSH release
We can give them GnRH which stimulates FSH and LH release
Then do many blood tests and plot them (every few mins for an hour)
How can we diagnose hypopituitarism with imaging?
Pituitary MRI
May revela specfic pituitary pathology e.g. haemorrhage, adenoma
Empty sella - thin rim of pituitary tissue
How do we treat hypopituitarism?
Replacement apart from prolactin
How do we treat GH deficiency?
NICE guidance
Assess QoL using specific questionnaire repeatedly
Daily injection
Measure response by
- improvement in QoL
- IGF 1
How do you treat TSH deficiency?
Replace with once daily levothyroxine
TSH will be low you cannot use this to adjust dose as you do in primary hypothyroidism
Aim for fT4 to be within reference range
How do you treat ACTH deficiency?
Replace cortisol rather than ACTH
Difficult to mimic diurnal variation
Two option in UK using synthetic glucocorticoids
- Prednisolone once daily AM
- Hydrocortisone
Why are there rules for patients for ACTH deficiency?
They are at risk of adrenal crisis which is triggered bu intercurrent illness
They MUST take tablets every day
What are the features of adrenal crises?
Dizziness Hypotensions (less common) Vomiting Weakness Collapse and death
What are the ‘sick day’ rules?
Steroid alert pendant/bracelet
Double steroid dose if fever/intercurrent illness
Unable to take tablets (e.g. vomiting) inject IM or come straight to A&E
How do you treat FSH/LH deficiency for men?
If they don’t need fertility
- replace testosterone (topical or IM)
- measure plasma testosterone
- does not restore spermatozoon production
How do you treat FSH/LH for men with fertility?
Induction of spermatogenesis by gonadotrophin injections
best response if secondary hypogonadism has developed after puberty
measure testosterone and semen analysis
sperm production may take 6-12 months
How do we treat FSH/LH deficiency for women?
No fertility
- replace oestrogen
oral or topical - will need additional progestagen if intact uterus to prevent endometrial hyperplasia
- mimics normal menstrual cycle
How do we treat FSH/LH deficiency for women with fertility?
Can induce ovulation via IVF
