1b Hypopituitarism & Anterior Pituitary dysfunction Flashcards by Mia Cameron

what are the anterior pituitary hormones

Growth Hormone
Prolactin
Thyroid stimulating hormone
Lutenising hormone/Follicle stimulating hormone
Adrenocorticotrophic hormone

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What does FSH and LH do in men?

FSH: spermatogenesis
LH: testosterone production

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where does the pituitary sit

sella turcica of sphenoid bone

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what does the anterior pituitary rely on?

the hypothalamus (to regulate function by releasing or inhibiting factors)

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what factors are released by the hypothalamus for the AP

growth hormone releasing hormone
somatostatin
thyrotrophin releasing hormone
dopamine
gonadotrophin releasing hormone
corticotrophin releasing hormone

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what is a primary endocrine disease

disease where the pathology originates in the gland itself e.g ovaries

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what is a secondary endocrine disease

disease where the pathology originates in the signals from the hypothalamus/anterior pituitary

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what is primary hypothyroidism

thyroid doesn’t produce thyroxine
Hashimotos - autoimmune
T3&4 fall TSH high

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what is secondary hypothyroidism

thyroid functioning, no releasing signals

TSH falls, T3/4 fall

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Why can’t we measure TSH or CRH

located only in hypothalamic pituitary portal system

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what is primary hypoadrenalism

Addisons disease
adrenal cortex damaged/destroyed by autoimmune eg TB
ACTH high, cortisol low

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How do we measure fT4?

Measure for 6 days

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what is secondary hypoadrenalism

adrenal cortex functioning,
but can’t make ACTH
ACTH falls, cortisol low

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When do we take cortisol measurements?

suspected hypo: 9am cortisol (when it should be at its highest)
suspected hyper: midnight cortisol (when it should be at its lowest)

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what is primary hypogonadism

gonads not functional

LH and FSH high, test/oest low

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Another test to measure ACTH and GH

Insulin tolerance test, give them hypoglycaemia to see if release of these hormones (GH and ACTH) are normal and then measure Cortisol to see if its primary or secondary.

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what is secondary hypogonadism

gonadotrophs (pituitary) damaged/hypothalamus damage

LH/FSH fall, test/oest fall

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congenital causes of hypopituitarism

mutations for anterior pituitary transcription e.g PROP1

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pattern of cortisol hormones

diurnal

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what are the signs of congenital hypopituitarism

deficient in GH (main one) & at least one more hormone since birth

hypoplastic (underdeveloped) anterior pituitary

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acquired causes of hypopituitarism

Tumours
infection eg meningitis
traumatic brain injury
pituitary surgery
pituitary apoplexy/ haemorrhage
peri-partum infarction (sheehan’s syndrome)

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what is hypophysitis

inflammation of the pituitary or infundibulum

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What does hypopituitarism usually describe?

Anterior pituitary dysfunction

what is pituitary apoplexy

bleeding into a pituitary adenoma (causing sudden enlargement and damaging the pituitary)

What is panhypopituitarism?

Total loss of anterior and posterior pituitary function

what is the name for complete loss of pituitary function (post. and ant.)

panhypopituitarism

what are the causes of pituitary apoplexy

haemorrhage | less commonly infarction

what procedures may cause radiotherapy-induced hypopituitarism

``` acromegaly treatment (radio right to pit.) nasopharyngeal carcinoma treatment (indirect) ```

what hormones are most sensitive to radioactivity

Growth hormone and gonadotrophins and prolactin | Prolactin

how long does the risk of radiotherapy persist for?

up to 10yrs | requires annual assessment

How does radiotherapy cause hypopituitarism?

**destroys** DNA so cell eventually die - brain cell have slow turnover so can take years

how does hypopituitarism affecting LH/FSH present?

reduced libido secondary amenorrhoea erectile dysfunction reduced pubic hair

how does hypopituitarism affecting ACTH present?

fatigue | no salt balance issues

how does hypopituitarism affecting TSH present?

fatigue, weight gain

how does hypopituitarism affecting GH present?

reduced quality of life, short stature in children

how does hypopituitarism affecting Prolactin present?

inability to breastfeed

what is sheehan's syndrome?

post-partum hypopituitarism secondary to hypotension/post-partum haemorrhage

how does sheehans syndrome happen?

pituitary swells so anterior pituitary is more likely to be damaged following hypotension during delivery, causing pituitary infarction

what are the signs of sheehans syndrome

lethargy, anorexia, weight loss, failure of lactation!!, failure to resume menses!!! !!- most obv

what happens to the pituitary during pregnancy

enlargement **(lactotroph hyperplasia)

why is only the anterior pit affected in sheehans

diff portal system

what is the onset of pituitary apoplexy?

dramatic and sudden | often precipitated by anti-coagulants

what are the signs of pituitary apoplexy

severe sudden onset headache visual field defect - bitemporal hemianopia possible diplopia and ptosis (droopy eyelids)

how does apoplexy show up on MRIs and what is it treated by?

- anticoags - white ball

what methods can be used to diagnose hypopituitarism

blood tests, dynamic pituitary function tests (stress test), pituitary MRI

what hormone dysfunction cannot be treated

prolactin

what is the guidance for treating hypopituitarism affecting GH?

daily injection of GH | measure response by improvement in quality of life and plasma IGF-1

how to confirm GH treatment is working

assess quality of life and measure response to this | measure plasma IGF-1

what is the guidance for treating hypopituitarism affecting TSH

once daily levothyroxine | aim for fT4 above middle of reference range

what is the guidance for treating hypopituitarism affecting ACTH?

prednisolone once daily AM or hydrocortisone 3x daily

what is an adrenal crisis

dizziness, hypotension, vomiting, weakness triggered by intercurrent illness can collapse and die

what should patients taking replacement steroids be advised to do?

keep steroid alert pendant double steroid dose if fever/intercurrent illness if unable to take tablets, inject IM or come to A&E

what are the guidelines for hypopituitarism affecting LH/FSH in men?

replace testosterone topically or IM | if fertility required - gonadotrophin injections, sperm production should resume 6-12 months after

when is fertility in men best conserved?

if secondary hypogonadism developed after puberty (gonads are right size/development)

what are the guidelines for hypopituitarism affecting LH/FSH in women?

oral or topical oestrogen addition of progesterone if uterus is intact to prevent endometrial hyperplasia if fertility is required, carefully timed IVF and gonadotrophin injections can induce ovulation

signs/presentation of pituitary apoplexy

sudden onset - blood/haemorrhage in cavernous sinus | cranial III defect as blood compresses this - ptosis

radilogical diagonsis of hypopit?

empty sella apoplexy adenoma