C - K and Electrolytes Flashcards
what is the most abundant intracellular cation
K
give normal range of K
3.5 to 5 mmol/L
what regulates K
angiotensin 2
aldosterone
describe the ang / ald / K pathway
angiotensinogen –> angiotensin 1 (via renin from JGA)
angiotensin 1 –> angiotensin 2 (via ACE in lungs)
angiotensin 2 stimulates aldosterone in adrenals
aldosterone increases K and decreases N in kidney
which cells does aldosterone act on to increase K
principal cells in cortical collecting duct of kidney
what 2 things stimulate aldosterone production
K+ and ang 2
what electrical change causes K+ excretion
if LUMEN of principal cells in kidney is more negative then K+ is lost into lumen down electrical gradient
what R does aldosterone act on
mineralocorticoid R
are K and Na transported on the same transporter in the kidney
NO - separate transporters but their passage is linked by the electrical gradient equillibrium
describe the mechanism of how aldosterone increases K excretion
aldosterone increases the number of open Na channels –> more Na resorption –> lumen becomes more negative –> more K secreted out of cells into lumen
list 4 main causes of high K in order of commonness
1.) renal impairment
2.) drugs
3.) low aldosterone eg Addisons
4.) release of K from cells - rhabdomyolysis / acidosis
name 3 drug classes to cause high K
ACEi
ARBs
spironolactone
what ECG finding is seen with high K
peaked T waves
give the Mx of high K (inc doses)
10ml 10% calcium gluconate
100ml of 20% dextrose + 10 units of insulin
nebulised salbutamol
treat underlying cause
give causes of low K
GI loss - vomitting
renal loss - osmotic diuresis, high ald/cortisol, more Na to distal nephron
redistribution into cells - insulin / beta agonists / alkalosis
rare = renal tubular acidosis or low magnesium
