Endocrine disorders Flashcards
relationship between calcium level and PTH
if plasma calcium falls then PTH secretion increases
which thyroid hormone is more potent and which produced in larger quantity by the thyroid gland
T4 is produced more
T3 is more potent
what is congenital hypothyroidism
failure to produce the hormone from birth
symptoms of hypothyroidism
- reduced metabolism
- lethargy
- weight gain
- increased sensitivity to cold
symptoms of hyperthyroidism
tachycardia
weight loss
fatigue
similar effects of increased sympathetic activity
primary hyo/hyperthyroidism refers to what
it refers to problems with the thyroid glands itself
secondary hypo/hyperthyroidism refers to what
it refers to problem with the pituitary or sometimes the hypothalamus
what should you measure to look for hyper/hypothyroidisms
TSH
what are the levels of T3/T4 in primary/secondary hypo/hyperthyroidism
T3/T4 in primary hypothyroidism= LOW
T3/T4 in secondary hypothyroidism= LOW
T3/T4 in primary hyperthyroidism= HIGH
T3/T4 in secondary hyperthyroidism=HIGH
what are the levels of TSH in primary/secondary hypo/hyperthyroidism
TSH in primary hypothyroidism = HIGH
TSH in secondary hypothyroidism = LOW/NORMAL
TSH in primary hyperthyroidism = LOW
TSH in secondary hyperthyroidism = HIGH
Anatomy of the adrenal gland
you have the inner medulla and outer cortex
in order from outer to innermost layer you have in the cortex:
Zona glomerulosa- mineralocorticoids (aldosterone)
Zona fasiculata- Gluco-cortcoids(cortisol)
Zona reticularis - adrenal androgens
what are the disorders linked to adrenal hyperfunction
- excess cortisol (cushings syndrome)
- excess aldosterone( e.g conns syndrome)
what are the disorders linked to adrenal insufficiency
- Hypocortisolism
- Lack of aldosterone and cortisol (Addison’s)
is conns syndrome primary or secondary hyperaldosteronism
primary
what 2 things activates aldosterone secretion
- RAAS
- increased plasma [Na+]
How does RAAS work
specialised epithelial cells in the distal tubule called macula dense senses decreased sodium conc and communicates with juxtaglomerular cells which release rennin to the blood stream.
renin converts angiotensinogen to angiotensin I
and ACE converts angiotensin I to angiotensin II
what are some of the effects of angiotensin II
increased aldosterone secretion
vasoconstriction
increased thirst
what activates RAAS
reduced renal perfusion
Increased sympathetic activity
what will happen if there is too much aldosterone
too much aldosterone= increased sodium reabsorption = increased expansion of extracellular volume= increased blood volume = increased BP (hypertension)
what is useful in diagnosing primary hyperaldosteronism
Plasma aldosterone/ renin ration
Difference between Cushing’s disease and Cushing’s syndrome
Cushing’s disease is due to ACTH-secreting pituitary
adenoma. Cushing’s syndrome may also be due to
ectopic ACTH source
what test is done in differential diagnosis of Cushing’s syndromes
Dexamethasone test
what are the clinical features of Addison’s
anorexia fatigue hyperpigmentation hypotension normal to low plasma sodium conc normal to high plasma sodium conc high ACTH Elevated plasma renin
what is the hallmarks of Addison’s disease
high ATCH and low cortisol
ACTH stimulation test
Assess ability of adrenal to produce cortisol in response to ACTH
Short synacthen test
• Measure baseline cortisol (9am) and 30 min after 250 ug synacthen (synthetic ACTH) i.m.
• Adrenal insufficiency is excluded by an increase in cortisol of >200 nmol/L and/or a 30
min value >550
Long synacthen test
• Adrenal cortex ‘shuts down’ in absence of stimulation by ACTH — time needed to regain
responsiveness
• 3-day stimulation with synacthen
• In secondary (but not primary) adrenal insufficiency cortisol increases by >200 nmol/L
over baseline
• Long test not often necessary since ACTH assay can distinguish
