Principles of Endocrinology Flashcards
most diverse hormone subtype?
proteins and peptides
what are prehormones?
large inactive hormones that undergo proteolytic change
name the 4 main hormone receptors
GPCR
receptor tyrosine kinase
steroid hormone receptors
cytokinase receptors (linked to TK activity)
what hormone receptor does insulin use?
tyrosine kinase receptor
what are the main chemicals involved in signalling cascades within GPCR?
cAMP
IP3
what receptors are seen as the main sensors of the internal environment?
GPCR
what happens to TK receptors when insulin binds?
undergo a conformational change
name 2 hormones that perform signalling via TK activity?
prolactin receptor
growth hormone receptor
are steroid hormone reeptors usually intra or extra cellular?
intracellular
where in the cell are steroid receptors typically located?
cytoplasm
nucleus
what is the main aim of hormones that signal via steroid hormone receptors?
to change gene transription
how does the hypothalamus control release of hormones from the anterior pituitary?
via hypothalamic releasing hormones
main determinant of hormone concentration?
rate of secretion
what is the only hormone not to be triggered by hypothalamic secretion?
prolactin
what hormones should be tested regularly?
thyroid steroid GH reproductive and sex hormones prolactin
2 types of negative feedback?
short or long acting loop
what would a normal TSH indicate?
normal thyroid
what would a raised TSH indicate?
hypothyroid
what would a suppressed TSH indicate?
hyperthyroid
when would TSH not be a reliable marker of thyroid status?
if you have pituitary disease eg secondary hypothyroidisim or pituitary cancer
what is your first line hormone test?
TSH levels
what hormone test would you do if the first line test was normal?
T3/4 levels
are thyroid levels affected in illness?
yes, you get low free T3/4 and low/normal TSH
what are the most important hormones for survival?
cortisol
thyroid hormones
what are the least important hormones in terms of survival?
sex
growth hormone
what hormones are lost first in pituitary dysfunction?
sex
GH
what hormone is affected in diabetes insipidus?
ADH
what imaging can be used to look at the thyroid?
MRI
what is a synacthen test?
tests the adrenal gland for ACTH production (synACTHen)
how is cortisol made
hypothalamus secretes corticotropin releasing hormone
anterior pituitary secretes ACTH
reaches the adrenal cortex
stimulates adrenal cortex to release cortisol
when is the best time to measure cortisol levels in suspected cushing’s syndrome and why?
midnight, should be virtually 0 in normal people but will be high in cushings
measurement of what protein can indicate GH hypersecretion?
IGF-1
how do hormones regulate their own secretion once they are released?
via negative feedback
when is the best time to measure testosterone?
9am
where are a female’s sex hormones at their highest?
around ovulation (all depends on menstrual cycle)
what cells in the anterior pituitary gland release prolactin?
lactotroph cells
what hormone inhibits prolactin?
dopamine
does an ncrease or decrease in prolactin affect fertility?
too much
a decrease in prolactin puts you at risk of what disease?
hypogonadism
what drugs are a particular cause of hyperprolactinaemia?
dopamine antagonists
does angiotensin 1 or 2 act on the hypothalamus to get it to release vasopressin?
angiotensin 1
how does vasopressin increase arterial pressure?
contricts blood vessels
increases fluid reabsorption at kidneys
what part of the pituitary secretes vasopressin?
posterior
what hormones are derived from cholesterol?
aldosterone
cortisol
sex hormones
what kind of test would you do for a hormone excess?
suppression test
what kidn of test would you do for a hormone deficiency?
stimulation test
should you do imaging or biochemical testing first?
biochemical testing
where is the pathology in cushing’s disease?
pituitary gland
is cushings from an excess or deficiency in cortisol?
excess
what test would you do for cortisol excess?
dexamethasone suppression test
what test would you do for cortisol deficiency?
synacthen test
clinical presentation of cushings?
moon face acne testicular atrophy fat pads on back (hump) proximal myopathy
what causes pituitary cushings?
tumour from corticotroph cells in anterior pituitary
what causes ACTH independent cushings?
adrenal adenoma
what can cause ectopic ACTH production?
malignancy
1st line screening test for excess cushings?
1mg overnight dexamethasone suppression test
1st line screening test for ACTH?
ACTH
