Potassium Disorders

Question 1

is potassium found inside or outside cells

Answer 1

major intracellular ion

amount measured in blood is lower than the total amount in the body

Question 2

normal plasma K levels

Answer 2

3-5 mEq/L

Question 3

K+ sources - internal and external

Answer 3

external: diet
internal: intracellular fluid (gets pumped back into ICF by Na/K pumps)

Question 4

major systems affected by K dysregulation

Answer 4

1. cardiac
2. neuromuscular

Question 5

how is potassium eliminated

Answer 5

kidneys

Question 6

which is more severe - hyper or hypokalemia

Answer 6

hyperkalemia - emergency

hypokalemia requires treatment but is not urgent

Question 7

causes of hyperkalemia

Answer 7

1. decreased excretion
2. increased intake (RARE)

Question 8

causes of decreased K excretion

Answer 8

• kidney failure (AKI)
• post-renal obstruction
• addison’s disease
• chronic body cavity effusions

Question 9

clinical signs of hyperkalemia

Answer 9

1. cardiac arrhythmias
   - visible at K > or = 6.0
2. generalized weakness/NM signs

Question 10

hyperkalemia ECG

Answer 10

• absent P wave
• tall T wave
• wide QRS complex
• +/- asystole or ventricular fibrillation

Question 11

hyperkalemia treatment

Answer 11

EMERGENCY
1. IV calcium gluconate
2. IV fluids
3. +/- dextrose + insulin
4. +/- beta agonists

Question 12

role of calcium gluconate in hyperkalemia treatment

Answer 12

cardioprotectant - works rapidly to protect heart from excess K+

does NOT lower blood K+

Question 13

role of fluids in hyperkalemia treatment

Answer 13

increases GFR to increase renal elimination of K+

dilutes K+ in ECF space

Question 14

role of dextrose and insulin in hyperkalemia treatment

Answer 14

insulin: facilitates movement of K+ into cells with glucose

ALWAYS supplement dextrose first to avoid hypoglycemia

Question 15

role of beta agonists in hyperkalemia treatment

Answer 15

terbutaline or albuterol

increase cycling rate of Na/K pumps to put K back into cells

CONTRAINDICATED in heart disease patients

Question 16

pseudohyperkalemia

Answer 16

lab abnormality resulting in abnormal reading of K+ despite patient having normal K+

Question 17

causes of pseudohyperkalemia

Answer 17

1. thrombocytosis - causes platelet degranulation and K release in serum samples
2. hemolysis in japanese breeds

Question 18

causes of hypokalemia

Answer 18

1. increased excretion
2. decreased intake
3. toxins (B agonists)

Question 19

causes of increased K+ excretion

Answer 19

• kidney disease (CKD)
• diuretics
• GI losses (diarrhea, vomiting)

Question 20

causes of decreased K+ intake

Answer 20

• IV fluids without supplementation
• vomiting
• anorexia

Question 21

clinical signs of hypokalemia

Answer 21

1. muscle weakness
   - cervical ventroflexion
   - hypoventilation

Question 22

ECG changes with hypokalemia

Answer 22

• absent T waves
• tall P waves

Question 23

hypokalemia treatment

Answer 23

NOT AN EMERGENCY
1. IV potassium in fluids
2. treat underlying process
3. +/- magnesium supplementation

Question 24

how much IV potassium

Answer 24

max dose: 0.5 mEq/kg/hr

ALWAYS have ECG monitoring while supplementing

Question 25

when to supplement magnesium

Answer 25

severe hypokalemia that does NOT respond to treatment

low Mg can exacerbate low K