Transition block: biochemistry Flashcards
What will the osmolality be of diluted urine?
low
What controls sodium balance?
steroids eg. aldosterone
What is Na+ reabsorption in exchange for?
K+/H+ excretion
Which body compartment is sodium confined to?
extracellular fluid
Give examples of non-osmotic stimuli for SIADH
hypovolaemia
hypotension
pain
N+V
Why are patient’s with Addison’s disease dehydrated?
not enough mineralocorticoid activity means sodium is lost from ECF and water goes with it
What happens when ADH is released in response to a non-osmotic stimulus?
water retention
hyponatraemia
Which type of fluid can go into all body water compartments?
dextrose
When are random cortisol measurements useful?
if someone is very ill (should be physiologically increased, so if low then adrenals are compromised)
Which type of adrenal insufficiency is associated with palmar pigmentation?
primary
lots of ACTH produced
Why are patients with hypercalcaemia rehydrated early ?
hypercalcaemia interferes with proximal tubular
reabsorption of sodium and so causes loss of sodium and water – patients are
usually dehydrated
Which part of the adrenal gland is affected in Addison’s?
cortex
How can you distinguish primary and secondary adrenal insufficiency?
short synacthen test
ACTH levels (inc in primary)
What does gross hyperkalaemia and hypocalcaemia suggest?
contamination with Potassium EDTA, the anticoagulant used in the FBC (purple top) bottles
Can long-term immobilisation result in hypercalcaemia?
bone loss will occur but PTH will compensate by dropping to reduce calcium
