Hyperkalemia

Question 1

What is the definition of hyperkalemia?

Answer 1

The presence of an abnormally high serum potassium level (usually > 5.5 mEq/L).

Question 2

What are the clinical features of hyperkalemia?

Answer 2

Symptoms (fatigue, weakness, paresthesias, palpitations)

EKG changes

Question 3

What are the EKG changes seen in hyperkalemia?

Answer 3

With increasing severity:

1. peaked T-waves
2. decreased QT interval
3. ST-segment depression
4. increased PR interval
5. widened QRS complex
6. decreased P wave amplitude
7. sine wave
8. VF or asystole

Question 4

What are the symptoms of hyperkalemia?

Answer 4

1. fatigue
2. weakness
3. paresthesias
4. palpitations

Question 5

What is the differential diagnosis for hyperkalemia?

Answer 5

1. Release of potassium into extracellular space. (K+ supplements, rhabdomyolysis, hemolysis, burns)
2. Decreased elimination of potassium (acute/chronic renal failure, potassium-sparing diuretics, adrenal insufficiency)
3. Transmembrane shifts (acidosis, meds like digitalis, betablockers, succinylcholine)
4. Pseudohyperkalemia (lysis of red cells in phlebotomy specimen)

Question 6

What are causes of release of potassium into the extracellular space resulting in hyperkalemia?

Answer 6

1. potassium supplements
2. rhabdomyolysis
3. hemolysis
4. burns

Question 7

What are causes of decreased elimination of potassium resulting in hyperkalemia?

Answer 7

1. acute/chronic renal failure
2. potassium-sparing diuretics
3. adrenal insufficiency

Question 8

What are causes of transmembrane shifts of potassium resulting in hyperkalemia?

Answer 8

1. acidosis

2. meds (digitalis toxicity, beta-blockers, succinylcholine)

Question 9

What is pseudohyperkalemia?

Answer 9

Elevated levels of potassium on a lab result due to lysis of red cells in phlebotomy specimen

Question 10

What is the management of hyperkalemia?

Answer 10

1. If no EKG signs, send stat VBG or ABG to confirm diagnosis before instituting treatment
2. If real, and K > 6 mmol/L or if EKG changes are present, start emergency treatment (calcium gluconate, insulin with dextrose, albuterol, diuresis)
3. Consider hemodialysis if life threatening or accompanied by volume overload
4. If mild, cation exchange resins (kayexalate) can be used to exchange K+ for Na+ in the gut

Question 11

What is the emergency pharmacologic treatment of hyperkalemia?

Answer 11

1. Calcium gluconate 10% 10cc IV over 2 - 3 minutes (raises threshold potential and restores myocyte excitability)
2. Insulin 10 units IV with 50mL of 50% dextrose (shifts K+ into cells. No effect on total body K+)
3. Albuterol 10 to 20mg by neb over 10 minutes (shifts K+ into cells)
4. Increase blood pH (mild hyperventilation, sodium bicarbonate 50 - 150 mEq)
5. Hemodialysis

(kayexalate is used in mild hyperkalemia)