• Hypokalemia treatment consists of two arms:
  • Treatment of the underlying cause
  • Potassium replacement therapy
• Potassium can be replaced orally/ enterally or intravenously.
  

  The severity of Hypokalemia

  • Mild hypokalemia if K 3-3.5 Meq/L.
  • Moderate hypokalemia if K 2.5-3 Meq/L.
  • Severe or critical if K < 2.5 Meq/L or any hypokalemia with symptoms. (arrhythmias, marked muscle weakness, or rhabdomyolysis).

  Hypokalemia-induced EKG changes

• All hypokalemic patients should get an EKG and placed on telemetry, this is particularly important in moderate-severe hypokalemia.
• Hypokalemia produces a wide range of EKG changes:
  • QT prolongation.
  • ST depression.
  • U waves.
  • PAC or PVC.
  • Sinus bradycardia.
  • Atrioventricular block.
  • Paroxysmal atrial or junctional tachycardia.
  • Ventricular tachycardia or fibrillation.

• The following patients are at highest risk of these arrhythmias
  • Patients on digoxin, antiarrhythmic drugs, and other QT-prolonging drugs.
  • Patients with CAD, CHF, or structural heart diseases.
  • Patients with a history of previous arrhythmias.

Potassium level targets

• 3.5 Meq/L for all patients including those at risk of arrhythmia!
• 3 Meq/L for renal failure patients, whether acute or chronic.
• 5-5.3 Meq/L for DKA/NKHH while on insulin drip.
• The target of 4 meq/L in cardiac patients and those at risk of arrhythmia isn’t necessary.
• Spurious hypokalemia is way less frequent compared to spurious hyperkalemia but can happen with extreme leukocytosis or when the blood sample sits for long before running the test.

Treatment

• Magnesium level should always be checked and corrected if low.
• Treat the underlying cause: Is hypokalemia due to K loss, redistribution, or both?

Potassium deficit

• The vast majority of potassium in the body is located intracellularly (IC). Thus, most of the total body potassium deficit represents deficient intracellular potassium.
• The serum K level represents the potassium level in the extra-cellular fluid.
• A small drop in ECF potassium likely represents a large deficit in the IC potassium.
• The total body potassium is proportional to the muscle mass and body weight. Muscle mass decreases with age.

Kdeficit (mmol) = (Knormal lower limit – Kmeasured) x kg body weight x 0.4

Daily potassium requirement is around 1 mmol/Kg body weight. 

Amount to be given = Kdeficit + Daily potassium requirement

• This equation is a rough estimate only and should be used, only, in hypokalemia due to potassium loss whether renal or extra-renal losses. If there’s an issue with potassium redistribution, this estimate may not be as accurate as in DKA.

Oral vs IV Potassium

• Potassium preparations are available for oral and IV administration.
• Mild and moderate hypokalemia should be treated with oral potassium only unless there’s a contraindication to the enteral route, then IV potassium can be used instead.
• IV potassium supplements should be reserved for severe or symptomatic hypokalemia.

Oral potassium

• Cheaper.
• Safer.
• Raise K level slowly.
• Larger doses.
• The risk of acute hyperkalemia is small.

IV potassium

• More expensive.
• Irritates the veins/phlebitis.
• Raise K level quickly.
• Smaller doses.
• May cause acute hyperkalemia

Potassium preparations

• Potassium chloride (KCL):
  • Is the most widely used one
  • Available in IV and oral preparation.
  • Pills and liquid

• Potassium Bicarbonate:
  • Available in oral form only
  • An optimal choice for hypokalemia and Non-anion gap metabolic acidosis

• Potassium citrate:
  • Available in oral form only.
  • Citrate is metabolized into bicarb in the body.
  • An optimal choice for hypokalemia and Non-anion gap metabolic acidosis.

• Potassium acetate:
  • Available in IV form only.
  • Metabolized into bicarb.
  • An optimal choice for hypokalemia and Non-anion gap metabolic acidosis.

• Potassium phosphate:
  • Available in oral and IV forms.
  • Can be considered when hypokalemia and hypophosphatemia exist together.

Patients selection:

• Hypokalemia + Non-anion gap metabolic acidosis (Diarrhea, RTA 1,2):
  • Potassium bicarbonate.
  • Potassium Citrate.
  • Potassium acetate (IV only).
• Hypokalemia + Hypophosphatemia:
  • Potassium phosphate.
• All other hypokalemias:
  • Potassium chloride.

   

Potassium administration

• Replace potassium deficit in divided doses (reduce the dose in Renal failure).
• A 120 meq deficit, for example, can be replenished with KCL 40 meq every 8 hours x 3 doses.
• IV potassium:
  • Infuse at 10 meq/hour in Mild-moderate hypokalemia (Use only if the enteral route is contraindicated).
  • Infuse at 20 meq/hour in severe or symptomatic hypokalemia.
  • Infuse at 20-40 meq/hour in DKA/NKHH to quickly raise potassium to a safe level (3.3 meq/L)  to start the insulin drip.
  • In Cardiac arrest due to hypokalemia, 10-20 meq can be infused over 3-5 minutes, and this is the only time we give potassium that fast.
  • If the patient keeps losing the pulse, potassium can be infused at a rate of 60 meq/hour.
  • Use precautions in renal failure patients, the amount and the rate of infusion should be probably reduced by 25-50%, frequent monitoring is the key.
  • Rates of 20 meq/hour and above should be given via a central line. If a central line isn’t available, split the amount and give it via multiple peripheral lines.

Monitoring:

• All patients should be on telemetry.
• For mild hypokalemia, repeat K with the next morning’s labs.
• For moderate hypokalemia, repeat K in 6-8-12 hours.
• For severe hypokalemia, monitor potassium every 2-4 hours.
• For potassium infused >=40 meq/hour, monitor every 60 minutes.
• Potassium level should not be obtained directly from a line where potassium is being infused, this will give you falsely elevated potassium.
• Potassium supplements are provided until we achieve our target K-level
• Replete magnesium if magnesium deficiency exists.
• Potassium-sparing diuretics should be considered in hypokalemia secondary to other types of diuretics.
• The underlying problem should undergo simultaneous treatment.

Watch the video here

Thanks for learning with me!