Electrolyte 2: Hyperkalemia

What is hyperkalemia?

• K+ > 5

How does hyperkalemia develop?

• Potassium intake exceeds excretion

  • (True hyperkalemia)

• Transcellular distribution of potassium is disturbed

  • Extracellular shift of potassium

How does oral/IV K+ cause hyperkalemia?

• Increased intake K+

How does digitalis cause hyperkalemia?

• Transcellular movement of K+

How does CKD, acute kidney injury, ACEI, ARBs cause hyperkalemia?

• Impaired renal excretion of K+

How does acidosis cause hyperkalemia?

• Transcellular movement of K+

• Impaired renal excretion of K+

What are the primary causes of hyperkalemia?

• Increased potassium intake

• Impaired potassium excretion

  • AKI or stage 4-5 CKD

  • Drug induced hyperkalemia: ACEI, ARB, NSAID, direct renin inhibitors, potassium sparing diuretics

  • Tubular unresponsiveness to aldosterone

• Redistribution of potassium into the extracellular space, metabolic acidosis, diabetes mellitus, or lactic acidosis; drug induced redistribution of potassium: B-blockers

What can cause an erroneously elevated potassium? (false elevated)

• Hemolysis

What is mild hyperkalemia and the symptoms?

• 5.1-5.9

• May be asymptomatic

• Muscle twitching, cramping, weakness

What is moderate to severe hyperkalemia and its symptoms?

• Moderate: 6-7

• Severe: >7

• Sx: arrythmias, death

What are general sx of hyperkalemia?

• Abnormal heart rhythms

  • PEAK T waves, flat P waves, ST depressed, widened QRS

• Muscular dysfunction

  • Flaccid paralysis (muscle weakness, reduced muscle tone, paralysis)

• MURDER

  • Muscle cramps, Urine abnormalities, respiratory distress, decreased cardiac contractility, EKG changes, reflexes

To determine is pt needs chronic vs acute hyperkalemia, what should they check?

• ECG, sx, etiology of hyperkalemia

What does it mean to treat underlying causes of hyperkalemia?

• Renal insufficiency (ex: CKD)

  • Missing dialysis appointments → acute hyperkalemia

  • Acute kidney injury → acute hyperkalemia

• Metabolic acidosis (ph down, K up)

• Meds that increase K+ → chronic or acute

  • K+ sparing diuretics, ACEI/ARBs, NSAIDs

How to manage CHRONIC hyperkalemia (CKD)?

• Promote physical removal of potassium

  • Cation-exchangers (aka potassium binders)

  • Dialysis (if already on dialysis)

How to manage ACUTE hyperkalemia?

• Shift potassium intracellularly

  • Insulin regular, sodium bicarbonate, beta-2 agonists

• Increase potassium excretion

  • Diuretics

• Promote physical removal of potassium

  • Dialysis

For the GI Cation-Exchangers, what are the 3 potassium binders?

• Sodium polystyrene sulfonate (SPS) (Kayexalate)

• Patiromer (Veltassa)

• Sodium Zirconium cyclosilicate (SZC) (Lokelma)

What is the MOA of the potassium binders?

• Binds to and INCREASES fecal K+ excretion

  • Non-absorbed cation exchange polymer that binds to K+ in exchange for a cation in the colon

  • Efficacy variable

For Sodium Polystyrene Sulfonate, what is it available as?

• Oral suspension and rectal suspension

How do you administer SPS?

• Suspend each dose in water/syrup

• Give at least 3 hours before or after other meds

What is the onset of Sodium Polystyrene Sulfonate?

• 1 hour

  • Sometimes given adjunct in acute hyperkalemia

What are some AE of Sodium Polystyrene Sulfonate?

• N/V, constipation, fecal impaction, hypoCa2+, hypoK+

  • Serious: GI obstruction, necrosis (FDA warning)

What is the MOA of Patiromer?

• Non-absorbed cation exchange polymer that binds to K+ in exchange for Ca2+ in the distal colon

How do you administer Patiromer?

• Powder → does not dissolve

• Give at least 3 hours before or after oral meds

• Do NOT heat or add heated foods/liquids

When is the onset of Patiromer?

• 7 hours (peak K+ lowering in 48 h)

  • NOT used for acute hyperkalemia (only chronic)

What are the AE in Patiromer?

• Constipation, hypomagnesemia

What is the MOA of sodium zirconium cyclosilicate?

• Non-absorbed cation exchange polymer that binds to K+ in exchange for H+ and NA+ in the distal colon

How to administer Sodium Zirconium Cyclosilicate?

• Add powder to at least 3 tbsp water

• Give at least 2 hours before or after oral meds

When is the onset of Sodium Zirconium Cyclosilicate?

• 1 hour

  • Sometimes given as an adjunct in acute hyperkalemia

What is an AE of Sodium Zirconium Cyclosilicate?

• Edema

What are the Acute HyperK management?

• Calcium

• Albuterol

• Bicarbonate

• Insulin

• Glucose

• K+ binders

• Dialysis

• “C a BIG K Drop”

What do you first give in acute hyperkalemia?

• IV calcium to stabilize cardiac membrane

  • NOTE: calcium does NOT decrease serum K+

  • Purpose: raise the depolarization threshold AKA protect the heart

What are the Calcium IV products?

• Calcium Chloride (CaCl3)

  • Administer 1g as slow IVP via central line

  • Available as vial or prefilled syringe

  • 3x more elemental calcium than calcium gluconate

  • Can cause tissue necrosis so central line preferred unless cardiac arrest/code blue (emergency)

• Calcium Gluconate

  • Administer 1 g IVPB over 10 min or slow IVP

After Calcium, what do you want to do?

• Shift K+ into cells

  • Intracellularly shift K+

What is 1st line for shifting K+ intracellularly? For this agent, what do you do depending on blood glucose levels?

• Insulin REGULAR 5-10 units IVP

  • If blood glucose <250 mg/dL, then also give 25-50g (50-100 mL) D50W to prevent hypoglycemia

  • Check BG Q30 min for 2 hours or more and monitor potassium

What else shifts K+ intracellularly and can be given adjunct to insulin?

• Sodium bicarbonate 50-100 mEq slow IVP

  • Adjunct to insulin, use if pt has metabolic acidosis or hyperkalemia from toxicological etiology

• Nebulized albuterol 10-20 mg nebulizer over 10 min

  • Adjunct to insulin, commonly used on ambulance for hyperK

What do you do after shift K+ into cells?

• Remove K+ from the body

What can remove potassium from the body?

• Potassium binders

  • Sodium poluysterene sulfonate (Kayexelate) or Sodium Zirconium Cyclosilicate may be used as adjunct if pt has acute or chronic hyperkalemia

• Furosemide 20-40 mg IV

  • Adjunct; only usr if pt has good renal function

• Dialysis

  • NOT used in all cases

  • Use if patient is ALREADY ON DIALYSIS

  • Use if pt having SEVERE ARRHYTHMIAS or needs dialysis for toxin removal (overdose situations)