Electrolyte Imbalance Flashcards
normal intracellular K level
3.5-5 mmol/L
elimination of potassium
secretion from distal tubules
homeostasis of potassium levels affected by
hormones
acid base status
hyperosmolality
how insulin affects potassium levels
stimulates NA K ATPase pump to transport K+ intracellularly
how catecholamines affect potassium levels
betat receptor stimulation activates the pump to drive K intracellular
causes break down of glycogen which increases glucose and releases insulin driving potassium intracellularly
how does aldosterone affect potassium levels
acts at distal tubule, increases the urinary potassium excretion
decreased pH affect of K
moves H into cells and K out
.1 decrease in pH = .7 increase in serum K
why is the increase K when blood pH decreases called false hyperkalemia
not actually increasing the total amount just shifting K into serum
increased blood pH effect on K
moves H out of cells and K in
.1 unit increse in PH = .6 decrease in serum K
false hypokalemia
hyperosmolality effect on K
K shits to extracellular fluid
mild hypokalemia
3.1 - 3.5
mod hypokalemia
2.5-3
severe hypokalemia
<2.5
effects of hypokalemia
mod - cramps, weakness, myalgia
sev - EKG, arrhythmia, increased dig toxicity
causes of hypokalemia
GI loss
metabolic alkalosis
hypomagnesemia increases renal excretion of K
100mmol of oral replacement increase serum K by
1mmol/L
oral K replacement products
potassium chloride liquid
potassium citrate 25meq tablets
slow k 8 meq
dosing of oral K replacement
more nore than 24meq per dose to avoid GI irritation or 50meq of liquid and wait 2hrs between doses
slow k dosing in chronic K deficiency
8-16meq daily
use IV K replacement if
severe hypokalemia
vomiting
monitoring in acute setting correcting severe hypokalemia
monitor serum levels numerous times daily
EKG with high rate infusions
monitoring inpatient in mild-mod acute K deficiency
replace and check serum levels daily to every 3 days
if K replacement is not correcting serum levels check…
magnesium levels
ambulatory setting K supplement monitorin
check serum level and renal function every 1-2 months once stable
mild hyperkalemia
5.1-5.9
moderate hyperkalemia
6-7
severe hyperkalemia
> 7
problems with hyperkalemia
usually asymptomatic when mild
more severe EKG changes, arrhythmias, mortality
4 main causes of hyperkalemia
increase K intake
decreased K excretion
decreased effect of aldosterone
extracellular movement of total body potassium (pseudo)
foods with high potassium
potatoe prunes carrots yogurt milk orange juice bananas KCL salt substitutes
increased intake of K usually only a problem in …
severe renal impairment or dialysis
causes of impaired K excretion
renal failure ACEIs ARBs K sparing diuretic NSAID minor: digoxin, tmpsmx, heparin
what is blood sample hemolysis
if sample sits too long intracellular K can spill from RBC
falsely elevated serum K
first step in severe hyperkalemia treatmemt
stabilize the cardiac membrane with IV calcium
doesnt change K levels
calcium gluconate 1g IV
ways to drive K intracellular in severe hyperkalemia
regular insulin 10units IV* x 1 + dextrose
or
beta 2 agonists salbutamol 10mg nebule inhaled x 1
if not hyperglycemic and giving insulin have to give**
dextrose 25g IV
if severe hyperkalemia from metabolic acidosis
sodium bicarc 100mg to moves K back into cells
who wouldnt we treat severe hypokalemia with a beta blocker
ppl on beta blockers
why dont we give insulin SC for hyperkalemia
longer duration of effect than dextrose and patient becomes hypoglycemic
kayexalate MOA and use
exchanges K for Na in the intestine
mild hyperkalemia
15g
problems with kayexalate
may take hours for full effect
CI in bowel dysfunction
risk of colonic necrosis
ay bind other meds space by 6hr
treatment options for mild hyperkalemia
furosemide 40mg IV x 1
onset within minutes
monitoring of hyperkalemia
also see chart slide 28
K levels every 2 hr until <5
sodium bicarb not appropriate in
ESRD
normal sodium serum levels
135-147
rapid swings in sodium levels assiciated with
significant morbidity and mortality
hypovolemic hypotonic hyponatremia common with
thiazides
euvolemic hyponatremia associated with
SIADH
syndrome of inappropriate secretion of antidiuretic hormones
ADH retains water but losses sdoium
hypervolemic hyponatremia associated with
cirrhosis, HF, nephrotic syndrome
treatment of hypovolemic hyponatremia
IV nacl 0.9%
treatment of euvolemic or hypervolemic hyponatremia
fluid restriction first
rapid swings in sodium can cause
osmotic demyelination syndrome - damage to myelin sheath of the brainstem
rapdi water movement out of brain cells as serum osmolalty increases
can result in paralysis and death
rule of correcting sodium levels
never increase serum Na more than 12mmol/L/24hr*******
more conservative if chronic
