Potassium disorders

Question 1

Normal range of potassium

Answer 1

3.5 - 5 mEq/L
-most abundant intracellular electrolyte

Question 2

How are potassium levels regulated?

Answer 2

Na+/K+ ATPase

Question 3

Which tissue depends on potassium to function properly?

Answer 3

-Cardiac tissue

-regulation of membrane potential
-> can cause arrythmias

Question 4

Hypokalemia

Answer 4

< 3.5 mEq/L
-severe: < 2.5 mEq/L

S/sx: often asymptomatic
severe:
-Arrhythmias, cardiac changes, muscle cramping

Question 5

Causes of Hypokalemia

Answer 5

-poor dietary intake/ GI losses
-low magnesium -> increases excretion of K+ (Mg repletion is helpful in repletion of K+)
-drugs: ß2 agonists (albuterol), insulin, diuretics
-metabolic alkalosis

Question 6

Treatment of Hypokalemia

Answer 6

1. check Mg and replace if low

-supplement potassium: PO over IV, if possible
IV reserved for severe cases (<2.5 mEq/L)
if IV: not more than 10 mEq/L, not pushed but infused per hour! -> may cause arrhythmia

Question 7

How much does a patient’s serum K change after supplementation?

Answer 7

increase in 0.1 mEq (serum) for every 10 mEq/L given PO or IV

f.e.: patient’s serum lvl is at 3.1 mEq/L and we want to get to 3.5 mEq/L -> we need an increase of 0.4 -> so give 40 mEq/L PO or IV

Question 8

Causes of Hyperkalemia

Answer 8

-K: > 5 mEq/L
-Kidney disease (acute or CKD)
-hemolysis of blood sample - breakdown of cells and exposure of intracellular K -> increase in K

-tumor lysis syndrome
-Rhabdomyolysis
-overreaction of hyperkalemia

Question 9

Signs and symptoms of Hyperkalemia

Answer 9

-EKG changes (due to arrhythmias): peaked T waves
-muscle twitches, cramping, weakness

Question 10

Treatment of Hyperkalemia

Answer 10

Shifting drugs: moving extracellular K into the cell (temporary bc the K might move out again)
-Insulin + Glucose, ß2 agonists (albuterol) -> may cause hypokalemia, sodium bicarbonate

Eliminating drugs (given with shifting drugs): bind potassium in the intestine and facilitate its removal: Loops (in the kidneys)
Kayexalate (sodium polystyrene sulfonate)
Veltassa (Patiromer)
Lokelma (sodium zirconium cyclosilicate)
Hemodialysis

Complication Mitigation drugs:
Calcium chloride and calcium gluconate
-> they do not normalize the potassium, they only stabilize cardiac myocardium,
-used together with shifting and eliminating drugs in patients with peaked T waves

Question 11

MOA for Kayexalate (sodium polystyrene sulfonate)

Answer 11

-removes K
-exchange of K with Na in the intestine

-ADR: Electrolyte abnormalities, GI hemorrhage and ulcers, intestinal necrosis or perforation
-not often used anymore due to ADR

Question 12

MOA for Veltassa (Patiromer)

Answer 12

-removes K
-Cation exchange polymer that increases fecal K excretion

-ADR: electrolyte abnormalities, GI intolerance (constipation, diarrhea, nausea) - doesn’t have the bad GI ADR as seen in Kayexalate

Question 13

MOA for Lokelma (sodium zirconium cyclosilicate)

Answer 13

-K+ binder that exchanges K for H+ and Na in the GI lumen

-ADR: minimal