Endo - Hypopituitarism Flashcards
What are the 5 APG hormones?
- Thyroid stimulating hormone (thyrotrophin)
- Growth hormone (somatotrophin)
- LH/FSH
- Prolactin
- Adrenocorticotrophic hormone
What are the 5 APG cells?
Thyrotrophs Somatotrophs Gonadotrophs Lactotrophs Corticotrophs
How are APG hormones primarily regulated?
Mainly through hypothalamic inhibitory or leasing factors travelling from the hypothalamus to the APG cells via the portal circulation
Where does GH act?
Muscles and bones (and liver to give IGF-1)
Where does TSH act?
Thyroid gland
Where does FSH/LH act?
Gonads (ovaries F or testes M)
Where does prolactin act?
Mammary gland
Where does ACTH act?
Adrenal gland
What are the main affected sites in APG failure?
3 glands can fail for 2 main reasons:
Thyroid gland, adrenal gland and the gonads
How do we test for primary vs secondary hypothyroidism?
If TSH is low and T3/T4 are also low then 2
TSH high and T3/T4 low then 1
How do we test for primary vs secondary hypoadrenalism?
Low ACTH, Low cortisol = 2
High ACTh, low cortisol = 1
How do we test for primary vs secondary hypogonadism?
Low FSH/LH, Low sex hormone = 2
High FSH/LH, Low sex hormone = 1
What is a common cause for primary hypogonadism in men?
Mumps
What is a common cause for primary hypogonadism in women?
Chemotherapy
What is usually the cause of congenital hypopituitarism?
Ineffective APG development e.g. from the PROP1 mutation
What is the result of congenital hypopituitarism?
Deficient in growth hormone and at least one other APG hormone therefore they have a short stature and hypoplastic APG on MRI
What is the more common cause of hypopituitarism?
Acquired hypopituitarism
What are some of the causes for acquired hypopituitarism
Tumour (adenoma, metastasis, cysts) Radiation (hypothalamus or pituitary damaged) Infection e.g. meningitis Pituitary surgery Traumatic brain injury Inflammation (hypophysitis) Pituitary apoplexy (haemorrhage or infarction) Peri-partum haemorrhage (Sheehan's)
What do we call a total loss of APG and PPG function?
Panhypopituitarism
What is the common cause of panhypopituitarism?
Hypophysitis
Surgery
Why can radiotherapy cause hypopituitarism?
We can be giving radiotherapy for a pituitary reason such as acromegaly, or for a different reason such as a nasopharyngeal carcinoma
How can radiotherapy cause hypopituitarism?
The pituitary and hypothalamus are both very sensitive to radiotherapy and therefore can be damaged
How long does radiotherapy risk last?
10 years
What hormones are most affected from radiotherapy?
Growth hormone and gonadotropins are most commonly lost, whereas prolactin may increase
Presentation of FSH/LH deficiency?
Libido
2º amenorrhoea
Erectile dysfunction
Loss of pubic hair or decrease in growth rate
Presentation of ACTH deficiency
Fatigue
Presentation of TSH deficiency
Fatigue
Weight gain
Presentation of GH deficiency
Quality of life decreases Short stature (children)
Presentation of PRL deficiency
Nothing in men
Decrease in post parts lactation (women)
What happens in Sheehan’s
Post partum haemorrhage leads to hypotension and thus pituitary infarction leading to post party hypopituitarism
What are the symptoms of Sheehans
Lethargy Anorexia Weight loss Failure to lactate Failure of post delivery menses
What is pituitary apoplexy
Intra pituitary haemorrhage or less commonly an infarction
How does pituitary apoplexy present?
Dramatic presentation associated with pre-existing adenomas therefore it may be the first presentation of the adenoma.
How do we stimulate GH release?
Induce stress response
How do we stimulate ACTH release?
Induce stress e.g. inject insulin to make them hypoglycaemic (glucose <2.2mM), stimulating an adrenergic stress response to cause GH and ACTH release
How do we stimulate TSH release?
Give TRH
How do we stimulate FSH/LH release?
Give GnRH
How do we diagnose hypopituitarism?
Can be diagnosed radiologically with an MRI showing an empty sella
How do we treat PRL deficiency?
Cannot be treated
How to treat Gh deficiency?
Make children their target weight with GH injection
With adults - give GH and plasma IGF-1 injections to see if their quality of life improves
How to treat TSH deficiency?
Levothyroxine once daily - aim for fT4 in the top half of the reference range
How to treat ACTH deficiency?
Prednisolone -3mg once every morning
Hydrocortisone (10mg, then 5mg, then 5mg again throughout day)
How to treat FSH/LH deficiency in men if fertility required
FSH/LH injections
Measure T/Sperm intermittently
Sperm production may return to normal in 6-12 months - normal gonad size produces the best response
How to treat FSH/LH deficiency in men if no fertility required
Topical/ IM testosterone
Measure plasma T
T doesn’t restore sperm production - just restores low libido and loss of pubic hair
How to treat FSH/LH deficiency in women if fertility required
Carefully timed gonadotrophin injection
How to treat FSH/LH deficiency in women if no fertility required
Oral/topical oestrogen
Intact uterus requires addition progesterone to prevent endometrial hyperplasia
What can cause pituitary apoplexy
Can be precipitate by anticoagulants
What are the symptoms of pituitary apoplexy
Headache (fast and sudden)
Visual field defect (bitemporal hemianopia)
Problems with eye movement - if blood enters cavernous sinus then CN 2, 3, 4, V1, V2, 6 can be affected
What is the purpose of sick day rules
If someone is on cortisol replacement with Addisons or secondary ACTH deficiency, they’re at risk of an adrenal crisis due to intercurrent illness
What can cause an adrenal crisis?
UTI or chest infection for example
What are the symptoms of a crisis?
Dizziness Hypotension Vomiting Weakness Collapse and death (potentially)
What are the sick day rules?
- Are you wearing a steroid alert pendant or bracelet?
- Double your steroid dose (glucocorticoid not mineralocorticoid), because during illness the body should be making more cortisol
- If you can’t take tablets due to vomiting, inject IM or come to A&E
