1b Hypopituitarism Flashcards
What are the five anterior pituitary hormones?
growth hormones, prolactin, thyroid stimulating hormone (TSH), luteinising hormone, follicle stimulating hormones (FSH), ACTH
What is the purpose of hypothalamic releasing factors?
travel in the portal circulation to the anterior pituitary to regulate anterior pituitary hormone production
What is primary disease in relation to the pituitary?
When the gland itself fails
What is secondary disease in r4elation to pituitary function?
when no signal are received from the hypothalamus or anterior pituitary
What happens to TSH and T3 and T4 when a patient has primary hypothyroidism? Why?
T3 and T4 fall and TSH increases - Primary = problem with the gland itself therefore thyroxine levels are lowered, and due to the negative feedback of TSH, this causes the levels to rise
What happens to T3 and T4 and TSH levels when a patient has secondary hypothyroidism?
TSH Falls as the patient cant make it from the pituitary, and because of this T3 and T4 also lower
Why is only cortisol impacted with disorders of the adrenal gland?
Cortisol is regulated by ACTH, aldosterone is through the renin-angiotensin system
What happens to cortisol and ACTH levels during primary hypoadrenalism?
Cortisol falls, ACTH Increases - this is due to destruction of the adrenal cortex
What happens to cortisol and ACTH levels during secondary hypoadrenalism?
pituitary tumour damaging corticotrophs
Can’t make ACTH
ACTH falls, cortisol falls
What happens to TESTOSTERONE/OESTROGEN and FSH/LH levels during secondary hypogonadism?
Can’t make LH/FSH
LH/FSH fall, and therefore Testosterone/oestrogen fall
What happens to Testosterone/Oestrogen and LH and FSH levels during primary hypogonadism?
Testosterone (men) or oestrogen (women) fall, LH
& FSH increase
Patients with congenital hypopituitarism?
Usually due to mutations of
transcription factor genes needed
for normal anterior pituitary
development
* Deficient in GH and at least 1
more anterior pituitary hormone
* Short stature
* Hypoplastic (underdeveloped)
anterior pituitary gland on MRI
What are some acquired causes of hypopituitarism?
- tumours, radiation, infection,
What is hypophysitis?
Inflammation of the pituitary
What is panhypopituitarism?
Total loss of anterior and posterior pituitary function
Describe the relationship between the dosage of radiotherapy and the risk of HPA Axis damage?
higher total dose = higher risk
Which hormones are most sensitive to Radiotherapy?
GH and gonadotrophins
Which endocrine organs are highly sensitive to radiation?
Pituitary and hypothalamus
Why is continual assessment required for patients with radiotherapy induced hypopituitarism?
Risk persists up to 10y after
radiotherapy, so annual assessment
What are the presentations of hypopituitarism (FSH/LH)?
Reduced libido
Secondary amenorrhoea
Erectile dysfunction
Reduced pubic hair
What are the presentations of hypopituitarism (ACTH)?
Fatigue
What are the presentations of hypopituitarism (TSH)?
Fatigue
What are the presentations of hypopituitarism (GH)?
Lower QoL
What are the presentations of hypopituitarism (PRL)?
no breastfeeding
What is Sheehan’s syndrome?
Post partum hypopituitarism secondary to hypotension (PPH - Post Partum Haemorrhage)
What happens to the anterior pituitary in pregnancy?
Enlarges - lactotroph hyperplasia
How does a post partum haemorrhage lead to a pituitary infarction?
Haemorrhage = blood pressure drops, as not enough blood to the enlarged pituitary = infarction as the pituitary is deprived
Why does the anterior pituitary enlarge in pregnancy?
enlarge as they prepare to lactate
Four key symptoms of sheehans?
Lethargy, anorexia, weight loss –
TSH/ACTH/(GH) deficiency
* Failure of lactation – PRL deficiency
* Failure to resume menses post-delivery
* Posterior pituitary usually NOT affected
Why is the posterior pituitary usually not affected by Sheehan’s syndrome?
posterior pituitary is a downward extension from the hypothalamus and therefore is neuronal tissue
What is a pituitary apoplexy?
Bleeding (Haemorrhage) into the pituitary or loss of blood flow (infarction) to the pituitary
What might be the first presentation of a pituitary adenoma?
Pituitary apoplexy
hat can help precipitate a pituitary apoplexy?
Anti-coagulants
What are the key symptoms of a pituitary apoplexy?
- Severe sudden onset headache
- Visual field defect – compressed optic chiasm,
bitemporal hemianopia
Why must you exercise caution when interpreting basal plasma hormone concentrations?
Cortisol – what time of day?
* T4 – circulating t1/2 6 days
* FSH/LH – cyclical in women
* GH/ACTH - pulsatile
How is the “stressed” state enduced when performing a dynamic pituitary function test?
Giving the patient insulin in order to replicate the hypoglycaemic state
What are the two “stress” hormones?
GH and ACTH Release
What does the insulin-induced hypoglycaemia stimulate?
GH release and ACTH Release
Why are MRI’s used to diagnose hypopituitarism?
Highest resolution - CT not good
What radiological landmark is looked for on an M RI of the pituitary?
Posterior pituitary bright spot
What is the treatment for GH deficiency?
- confirm GH deficiency on dynamic function test and assess QoL
- give daily injection
How is the effect of GH treatment measured?
Improvement in QoL and plasma IGF-1
What is the treatment for TSH deficiency?
Levothyroxine
What must you aim for when treating a TSH deficiency and why?
Aim for fT4 above the middle of the reference range - the TSH will be low therefore you cannot use this to adjust the dose
What challenge is faced hen treating ACTH deficiency?
Difficult to mimic diurnal variation of
cortisol
What are the two main treatment options for ACTH deficiency?
Prednisolone and hydrocortisone
What is an adrenal crisis?
dizziness, hypotension, vomiting,
weakness, can result in collapse and death
What is important to mention to patients who are on steroid replacement?
Sick Day Rules - must have a steroid alert bracelet
What happens to the dose of steroid if a patient with ACTH deficiency falls sick?
double steroid dose if they have a fever / intercurrent illness
What is the treatment for FSH/LH deficiency in men if fertility is and isnt required?
No fertility = replace testosterone (topical or intramuscular) as this does not impact sperm production
Fertility = 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
What is the treatment for FSH/LH deficiency in women if fertility is and isnt required?
No fertility = replace oestrogen (oral/topical)
Fertility = induce ovulation. by carefully timed gonadotropin injections
What will women need if they are receiving additional oestrogen?
Additional progesterone if intact uterus to prevent endometrial hyperplasia
Which hormone increases its levels after radiotherapy?
Prolactin
Sudden onset headache and bitemporal hemaniopia…what is the diagnosis?
Pituitary apoplexy
What are the signs of an adrenal crisis?
Dizziness, hypotension, vomiting, weakness and can result in collapse and death
Which patients should be told sick day rules?
Patients who take replacement steroids like prednisolone, hydrocortisone
What is seen on a MRI of the pituitary if there is a pathology?
Empty sella - thin rim of the pituitary tissue is visible
