Hypopituitarism Flashcards
What are the 5 main hormones of the anterior pituitary?
-GH
-Prolactin
-TSH
-LH/FSH
-ACTH
What is anterior pituitary failure?
Under functioning of the anterior pituitary gland
What are the 2 types of anterior pituitary failure?
- PRIMARY hypothyroidism (all fail-gland itself fails)
- SECONDARY hypothyroidism (no signal from hypothalamus or anterior pituitary)
Explain the congenital cause of hypopituitarism?
-Rare
-Mutations of transcirption factor genes needed for normal anterior pituitary development
-Results in hypoplastic (underdeveloped) anterior pituitary gland on MRI
-Deficient in GH and at least 1 more anterior pituitary hormone
-Results in short stature
List the acquired causes of hypopituitarism
*MORE COMMON
Tumours eg adenomas, metastases, cysts
* Radiation (hypothalamic/pituitary damage)
* Infection eg meningitis
* Traumatic brain injury
* Pituitary surgery
* Inflammatory (hypophysitis)
* Pituitary apoplexy - haemorrhage (or less
commonly infarction)
* Peri-partum infarction (Sheehan’s syndrome)
What is panhypopituitarism?
-total loss of anterior AND posterior pituitary
-Usually due to inflammation or surgery of the anterior pituitary causing damage to the posterior pituitary
Why are annual assessments required following radiotherapy to/around the pituitary?
- Higher total radiotherpy dose=higher risk of HPA axis damage
- GH and gonadotrophins most sensitive
- Hormones can deplete slowly
- Risk persists up to 10y after radiotherapy
What are the presentations of hypogonadism?
FSH/LH:
Reduced libido
Secondary amenorrhoea
Erectile dysfunction
Reduced pubic hair
What are the presentations of hypocorticolism?
ACTH:
Fatigue
NB Not a salt losing crisis (still has aldosterone due to reninangiotensin system)
What are the presentations of hypothyroidism?
Fatigue
What are the presentations of growth hormone deficiency
Reduced quality of life
NB short stature only in children
What are the presentations of hypoprolactinaemia?
Inability to breastfeed
Explain the pathophysiology of Sheehan’s syndrome
Caused by post partum haemorrhage
As you continue along the pregnancy:
-Lactotrophs get larger preparing for lactation after birth (lactotroph hyperplasia)
-Pituitary increases in size
-HAEMORRHAGE
-b.p. decreases
-blood does not fulfill the increased demand to pituitary (now that it’s larger)
-Pituitary infarction= decreases function
What are some symptoms of Sheehan’s syndrome?
- Lethargy (tired), anorexia, weight loss –
TSH/ACTH/(GH) deficiency (low cortisol) - Failure of lactation – PRL deficiency
- Failure to resume menses post-delivery (no period)-loss of FSH/LH
- Posterior pituitary usually NOT affected (anterior pituitary is made of glandular tissue and posterior is neuronal tissue- therefore unaffected by the haemorrhage
What scan would you do to monitor pituitary function?
- MRI
- Pituitary is v. small- found at the base of the skull
- Other scans do not have enough resolution
What is pituitary apoplexy?
Swelling due to filling of blood OR infarction
There are 2 types:
1. Bleeding (haemorrhage) into the pituitary
2. Loss of blood flow (infarction) to the pituitary
What are some symptoms 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 some cautions that need to be taken when diagnosing hypopituitarism?
- Cortisol – what time of day?
- T4 – circulating t1/2 (takes the T4 6 days to reduce to it’s half life)
- FSH/LH – cyclical in women
- GH/ACTH - pulsatile
What is a dynamic pituitary function test?
“Used to monitor pituitary function”
*to measure ACTH/GH- induce stress
-give patient insulin
-hypoglycemic (<2.2mM)
-adrenaline/ NA increases to restore blood glucose
-ACTH/ GH increases (ACTH difficult to measure- measure cortisol)
*to measure TSH- inject TRH
*to measure FSH & LH- inject GnRH
What is the treatment for GH deificiency?
- 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
What is the treatment for TSH deficiency?
- 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
What is the treatment for ACTH deficiency?
- 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 is “adrenal crisis”?
- Patients with primary adrenal failure (Addison’s) or secondary adrenal failure (ACTH deficiency) at risk of ‘adrenal crisis’ triggered by intercurrent illness
(cortisol usually increases to help fight illness) - Adrenal crisis features – dizziness, hypotension, vomiting, weakness, can result in collapse and death
What precautions must be taken for patients taking replacement steroids for ACTH deficiency?
- 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 do you treat FSH/LH deficiency in men?
If no fertility required:
* Replace testosterone – topical or
intramuscular most popular
* Measure plasma testosterone
* Replacing testosterone does not restore
sperm production (this is dependent on FSH)
if fertility required:
* 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 do you treat FSH/LH deficiency in women?
If no fertility required:
* Replace oestrogen
* Oral or topical
* Will need additional progestogen if intact uterus to prevent endometrial hyperplasia
Fertility required
* Can induce ovulation by carefully timed gonadotropin injections (IVF)
How do you treat FSH/LH deficiency in women?
If no fertility required:
* Replace oestrogen
* Oral or topical
* Will need additional progestogen if intact
uterus to prevent endometrial
hyperplasia
Fertility required
* Can induce ovulation by carefully timed
gonadotropin injections (IVF)
