Endocrine Flashcards
what are the characteristics of water soluble hormones?
fast clearance
short half life
what are the characteristics of lipid soluble hormones?
diffuse into cell
slow clearance
long half life
what are examples of water and lipid soluble hormones?
water- peptides, monoamines
lipid- steroids, thyroid hormone
which hormone switches off appetite?
leptin
which hormone switches on appetite?
Ghrelin
what is obesity?
excessive accumulation of fat which may impact on health
where is TSH produced?
pituitary gland
what effect does removal of the thyroid gland have on TSH levels?
raised TSH
what effect does an overactive thyroid gland have on TSH levels?
reduced TSH
screening for which hormone can be used to check thyroid activity?
TSH
where is TRH produced?
hypothalamus
where are T3 and T4 hormones produced?
Thyroid
what effect do T3 and T4 have on TRH production?
negative feedback
more T3/4 = reduced TRH production
what effect do T3/4 have on TSH production?
negative feedback
more T3/4 = reduced TRH production
production of TSH is stimulated by which hormone?
TRH
production of T3/4 is stimulated by which hormone?
TSH
where is dopamine produced?
hypothalamus
where is prolactin released from?
anterior pituitary
dopamine inhibits the release of which hormone from the anterior pituitary gland?
prolactin
pressure of the pituitary on the optic chiasm causes which classical presentation?
bitemporal hemianopia
where is cortisol produced?
adrenal glands
what is goitre?
enlarged thyroid
what are the signs of graves disease?
goitre, weight loss, insomnia
pretibial myxoedema, thyroid eye disease, thyroid acropachy
what affect does graves disease have on the thyroid?
excessive growth- hyperthyroidism
what effect does PTH have on bone?
causes increased bone resorption
what effect does PTH have on absorption of calcium?
increased absorption in small intestine
PTH regulated which ion?
Ca2+
when calcium in serum is low which hormone is stimulated to be released?
PTH
what is the cause of graves disease?
autoimmune IgG antibodies produced which mimic TSH by binding to receptors to stimulate T3/4 production. causing hyperplasia of follicular cells
how is graves disease diagnosed?
TSH levels low due to high T3/T4, TSHr antibodies high, ultrasound, radioactive thyroid uptake test
what are causes of hyperthyroidism?
graves disease (IgG antibodies), pituitary adenoma of thyrotrophs, toxic thyroid adenoma, amiodarone, iodine intake, thyroid medication
what are actions of T3/4?
INC METABOLISM, initiate transcription, CNS development, growth, inc gluconeogenesis, inc HR&CO, inc RR
what are the signs of hypothyroidism?
BRADYCARDIC
bradycardia, reflexes relax slowly, ataxia, dry skin, yawning, cold hands, ascites, round puffy face, defeated low mood, immobile, congestive HF
what are the causes of hypothyroidism?
autoimmune (anti thyroid auto antibodies), hashimotos, iodine deficiency, DM1, surgery
what is the treatment for hypothyroidism?
thyroid replacement- oral levothyroxine
describe hypothalamus pituitary thyroid axis?
TRH from hypothalamus causes TSH release from pituitary gland (thyrotrophs) which causes T3/4 production in thyroid gland (both have neg feedback on TRH)
what is the difference between cushings syndrome and disease?
syndrome is any reason for high cortisol, disease refers to a pituitary tumour of corticotrophs
what are exogeneous causes of cushings syndrome?
iatrogenic (e.g. steroid use for RA)
what are endogeneous causes of cushings syndrome?
cushings disease(pit tumour), ectopic acth tumour, adrenal adenoma/carcinoma
what effects can a pituitary tumour have on hormones?
GH from somatotrophs- acromegaly
TSH from thyrotrophs- hyperthyroidism
ACTH from corticotrophs- cushings disease
prolactinoma- prolactin from lactotrophs causes hyperprolactaemia
what effects does elevated cortisol have?
anxiety, depression, memory problems, cvd (hyperglycaemia), dampened immune system (infection), hypertension, central obesity, muscle wasting, osteoporosis, thin skin
how is cushings diagnosed?
random plasma cortisol, give oral dexamethasone then test cortisol (in healthy individual it has negative feedback on ACTH), MRI pituitary, CT adrenals, plasma ACTH
what does a low plasma ACTH in an individual who you suspect cushings in suggest?
adrenal tumour rather than pituitary tumour
what causes type 1 diabetes?
autoimmune destruction of beta cells in the pancreas, therefore insulin deficiency
what are the three common symptoms of type 1 diabetes?
polyuria/nocturia
polydipsia
weight los
how does ketoacidosis occur in type 1 diabetic?
breakdown of fatty acids for energy due to lack of glucose in the cells (low insulin), which causes acetyl coA to be produced and therefore ketones increase
what are the 4 P’s of type 2 diabetes?
polyuria, polydipsia, polyphagia, paraesthesia
what tests define diabetes?
fasting glucose > 7mmol/L
plasma glucose > 11.1mmol/L
Haemoglobin A1c > 48mmol/mol
what effects does insulin have?
DEC BLOOD GLUCOSE: increases uptake of glucose into fat/muscle cells, deceases hepatic glucose output, decreases gluconeogenesis/glycogenolysis/lipolysis
what effects does glycogen have?
INC BLOOD GLUCOSE: decrease uptake into fat/muscle cells, increases hepatic output, increases glycogenolysis/gluconeogenesis/lypolysis
what are the macrovascular effects of diabetes?
cerebrovascular events, limb ischaemia, coronary heart diease
what are the microvascular effects of diabetes?
retinopathy, nephropathy, neuropathy
what are symptoms/signs of acromegaly?
excessive sweating, large hands/feet, headache, visual problems/ sleep apnoea/ large brow, jaw, nose
insidious onset!
what is the name given to acromegaly in children and how does it differ?
giantism
before epiphyseal bone plates fuse in long bones
what are the treatments for acromegaly?
surgical removal, somatostatin analogues, GH antagonists
how is acromegaly diagnosed?
GH plasma test (not reliable due to pulsatile nature), IGF1 raised (production stimulated by GH), glucose tolerance test (glucose in blood has negative feedback on GH, inc bg and test GH), MRI for tumour
what is conns syndrome?
adrenal adenoma releasing aldosterone causing hyperaldosteronism
hows is conns syndrome diagnosed?
aldosterone renin ratio (low renin and high aldosterone), saline infusion and test aldosterone (not supressed in conns), CT/MRI tumour
treatment for conns syndrome?
laproscopic adrenalectomy
