Aani CP: Endocrine Flashcards
Which test do you do for pituitary function?
Triple test
What are the components of the triple test for pituitary function?
- IV insulin 0.15 Units/kg
- GnRH (100mg)
- TRH (200mcg)
Contraindications to the triple test?
- Ischaemic heart disease (hypo will cause MI)
- Epilepsy (hypoglycaemia will cause fit)
- Untreated hypothryoid
At what level does glucose stimulate pituitary?
<2.2
What happens in the triple test?
Insulin causes glucose to drop and then adrenaline is released
Side effects of triple test?
Aggressive, palps, sweaty, convulsions
TRH - metallic taste, nausea
What happens if glucose goes too low in triple test?
Rescue them with 50ml 20% dextrose - wide bore green cannula already in place
What should happen in order to raise glucose levels in triple test?
ACTH and GH should rise –> cortisol and GH increase glucose release to normalise glucose levels.
Cortisol shouldl get to 170-500nmol/l
GH should get to 6mcg/l
These rise in response to insulin lowering blood glucose
How high should a normal person’s cortisol get in response to the triple test?
Over 500nmol/l
In response to the triple test, if someone’s TSH remains low, what is the underlying diagnosis?
Hyperthryroidism because it is suppressing the TSH despite the action of TRH
If someone has 6000 prolactin, what do they have?
Prolactinoma
Which hormones are raised in acromegaly?
GH and prolactin
How to test if someone has acromegaly (test with hormones)?
GTT. Giving glucose should lower GH to 0 or undetectable e.g <0.3mcg.
If it does not = GH excess
What does TRH do?
Increases TSH and prolactin
What does prolactin do?
Secretion of milk Inhibits GnRH (causing amenorrhoea)
Treatment of pituitary adenoma?
Depends if it is secreting hormones.
Prolactin secreting? Give dopamine agonists e.g. Bromocriptine/Cabergoline
GH secreting? Give octreotide (mimics somatostatin) /surgery/radiotherapy
Side effects of dopamine agonists?
Excess dopamine = think manic. Super powers, gambling etc.
What does the prolactin level need to be to diagnose a functioning pituitary adenoma?
> 5000
If large pituitary tumour does not have high prolactin, what is it?
Non-functioning pituitary adenoma
Why are the prolactin levels still high in a non-functioning pituitary adenoma?
Because it is pressing on the pituitary stalk so dopamine cannot be released and so dopamine cannot suppress prolactin. = Secondary Hyperprolactinaemia
Which antibodies are in Hashimotos?
Anto Thyroid Peroxidase (Anti-TPO)
Hypothyroid - Low T4, high TSH
Which antibodies are in Graves?
TRAbs - Thyrotropin Receptor Antibodies
What is the T4 and TSH of subclincial Hypothyroid?
Normal T4
High TSH
May also have TPO Abs (susceptible to getting Hashimotos)
Why might a pregnant lady have low TSH?
hCG acts like TSH and stimulates T4 release (especially if high HCG). This feeds back and reduces TSH release
Management of hypothyroid?
Levothyroxine 50–1250–200 mcg/day
Why is T4 low in sick euthryoid?
Illnesses causes thyroid to shut down to reduce metabolic rate. Low T4, normal or high TSH
Treatment of Hyperthyroid?
Depends on cause. Always give Beta Blockers. In low uptake hyper - treat symptoms In high uptake - give Radioactive Iodine. OR drugs OR surgery Thionamines: - Carbimazole - Propylthiouracil (PTU) - not used often because of aplastic anaemia risk