[PCL] Hyperkalemia


Physiology of Potassium

  • Major intracellular cation

  • 98% of potassium found in the body is in the cell

  • 2% found in extracellular fluid

  • All cells maintain a negative voltage in the cell interior (-40 to -80 mV) which creates membrane potential

    • Difference in electric potential between the interior and the exterior of the cell

  • Membrane potential functions

    • Provides power to the molecular devices within the cells

    • Helps transmit signals to another part of the cell

      • Action potential in nerve cells

  • Depolarization

    • Ion channels open and allows electricity to flow (cell interior becomes less negative quickly)

  • Sodium/Potassium Pump maintains the balance of negative ions (aka potassium) inside the cell compared to outside the cell

  • Too much extracellular potassium leads to less of a membrane potential (cell exterior and interior match more closely)

    • Makes it easier for depolarization to happen

    • Causes cardiac cells to be more excitable and leads to potentially lethal arrhythmias

Causes of Hyperkalemia

Shifting of Potassium Out of the Cell

  • Acidosis

  • Diabetes Mellitus

  • Acute Cell Tissue Breakdown (rhabdo, hemolysis, massive transfusion)

  • Drugs: Digoxin, Beta Blockers (especially non selective ones)

Impaired renal elimination of potassium

  • Renal insufficiency

  • Hypoaldosteronism

  • Medications that interfere with potassium excretion

    • K sparing diuretics (spironolactone, NSAIDs, and ACEI/ARBs)

  • Congestive heart failure (or the drugs associated with them: BB, ACEI)

  • Constipation

Increased intake of potassium

  • With normal renal function it takes large amounts

  • With impaired renal function a smaller increase in potassium can cause severe hyperkalemia

Signs and Symptoms of Hyperkalemia

  • Rarely associated with symptoms

  • Some patients can complain of nausea, muscle pain, or parathesias

  • If patients are symptomatic; always check an EKG

EKG Changes in Hyperkalemia

  • First: Tall, peaked T waves

  • Second: Flattening of the p wave and prolongation of PR interval

    • Can see bradycardia and AV block

  • Third: Broad QRS Complexes

  • Eventually becomes a sine wave; cardiac arrest and Vfib are imminent

Treatment of Hyperkalemia: Emergency

  • How urgent do you need therapy?

    • Treat it urgently if you have EKG changes or the patient is symptomatic

  • Calcium is your mainstay treatment in emergent hyperkalemia

    • Calcium makes outside the cell more positive and increases the gradient of electrical charge so cells aren’t able to depolarize as easily

    • 1-3 minutes to take effect

    • Only lasts 30-60 minutes

  • Which type of Calcium?

    • Calcium Gluconate preferred because calcium chloride has a higher concentration of calcium and you want to avoid calcium toxicity

    • Calcium gluconate is safe to give peripherally

    • Calcium chloride can cause tissue necrosis and can be irritating to peripheral veins

  • Calcium is in; now what?

    • Rapidly remove potassium from the body

      • Hemodiaylsis

Treatment of Hyperkalemia: Non-emergent

  • Shift Potassium into the cells (don’t affect total body potassium)

    • Fluids

      • Dilutes total body volume and treats pre-renal AKI

    • D50 + Insulin

      • Insulin shifts potassium out of the vascular space and into the cells

      • D50 given to prevent hypoglycemia

    • Sodium Bicarbonate

      • Reversing acidosis which shifts potassium out of the cells (only works if the patient is acidotic)

    • Albuterol

      • Shifts potassium back into cells

      • Additive to insulin

      • Takes about 15-30 minutes to work, lasts 2-3 hours

      • 10 mg continuous neb (not the usual 2.5 mg)

  • Remove potassium from the body

    • Loop diuretic

      • Increases renal excretion of potassium (only effective if kidneys are working)

    • Kayexelate (sodium polystyrene sulfonate)

      • Removes potassium from the gut in exchange for sodium

      • Takes 1-2 hours to work

      • Lasts 4-6 hours

      • Associated with bowel necrosis and sodium retention


  • Hyperkalemia is defined as a potassium > 5.5 outside the cell

  • caused either by intracellular shift of potassium outside the cell, decreased renal excretion of potassium or increased exogenous intake of potassium

  • patients are typically asymptomatic but when it’s not, it’s usually life threatening and associated with EKG changes

  • Calcium is used to stabilize the heart by making the outside of the cell more positive and shifting the membrane potential closer to normal

  • For life threatening hyperkalemia, stabilize the myocardial membrane potential with calcium then rapidly remove potassium with a measure such as dialysis

  • In a patient with hyperkalemic arrest you can use albuterol with insulin/d50 to rapidly shift potassium inside the cell

  • To remove potassium from the body more slowly you can use Lasix (a loop diuretic) in patients with good renal function or kayexlate to remove potassium via bowel excretion – but both take longer to work


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