K+ Disorders (lec 3) Flashcards
K+ is major ion where?
intracellular
Major route of K+ elimination?
renal excretion
Regulation of K+ balance and excretion happens where?
distal nephron
K+ level for Hyperkalemia?
serum K+ > 5.0
> 6 = critical
Causes of HyperK+? (4)
1) pseudohyperK+ (false)
2) ↓ excretion
3) redistribution from ICF to ECF
4) excess administration
HyperK+ presentation:
Neuro?
EKG?
Neuro: weak, numb, flaccid, hypoactive DTR
EKG:
Early = tall, peaked T-wave
Final = sine wave w/ arrest
Most common cause of Pseudohyperkalemia?
hemolysis from poor venipuncture
broken RBCs release K+
Inadequate excretion etiology? (3)
Renal failure: check BUN/creatinine
Meds: K+-sparing diuretics (spironolactone)
Hypoaldosteronism:
Adrenal insuff
ACE inhib
NSAIDs
Redistribution of K+ from ICF to ECF caused by? (3)
tissue damage
acidosis
↓ insulin
How does acidosis (↓ pH) effect serum K+ levels?
- 1 ↓ in pH ->
0. 5 - 1.0 mEq/L ↑ in serum K+
Excess administration of K+ typically caused by?
Rx K+ supplements too high
K+-containing salt substitutes
HyperK+ tx?
1) r/o pseudo (repeat test)
2) correct levels
3) correct cause
Rapid correction of HyperK+? (3)
By IV:
1) CaCl (protect heart),
2) NaHCO3 (↑ pH),
3) D50W + insulin (dextrose keeps insulin from dropping glu too much)
Slow correction of HyperK+? (3)
Diuretics
Na+/K+ exchange resin (kayexalate + sorbitol)
Dialysis
K+ level for Hypokalemia?
serum K+ < 3.5
< 3 is dangerous
Causes of HypoK+? (4)
1) ↓ intake
2) GI loss
3) Renal loss
4) Redistribution from ECF to ICF
HypoK+ presentation:
Neuro?
EKG?
Other?
Neuro: malaise, weak, cramps, paralysis
EKG: U-waves
Polyuria/dipsia
Inadequate intake exacerbated by?
K+-losing meds (e.g. diuretics)
GI loss of K+ (U) from?
V/D
Fistula
tumor
Renal loss of K+ (U) from?
Diuretics Osmotic diuresis (hyperglycemia, alcohol)
Redistribution of K+ from ECF to ICF cause by?
alkalosis
↑ insulin
mineralocorticoid excess (steroids, cushings)
β-agonists: ↑ cellular K+ uptake and ↑ insulin secretion
HypoK+ tx?
*Digitalis makes hypoK+ more critical
1) Check for hypoMg (low Mg makes low K+ harder to correct)
2) find cause
If unknown, order 24º urine potassium
24º urine potassium results?
20 = renal loss
Rapid correction of HypoK+?
IV: KCl
Cardiac monitor
Check STAT K+ every 2-4 hrs
Slow correction of HypoK+?
oral K+
What med makes hypoK+ more dangerous?
Digitalis
