Hypokalemia

Notes
  • It is defined as a persistent potassium serum levels of below 3.5mmol/L

##Classification of hypokalemia

  • Mild hypokalemia – 3.1 to 3.5mmol/L
  • Moderate hypokalemia – 2.5 to 3.0mmol/L
  • Severe hypokalemia – below 2.5mmol/L

## Causes of hypokalemia:

  • Vomiting (results in loss of chloride ions that leads to elevation of aldosterone levels, which in turn inhibits potassium reabsorption from the renal tubules)
  • Diarrhea
  • Laxative abuse
  • Paralytic ileus
  • Fistulae
  • Furosemide and other loop diuretics
  • Hydrochlorothiazide and other thiazide diuretics
  • Inadequate dietary intake (not common)
  • Uncontrolled diabetes
  • Failure to give potassium supplements while treating DKA
  • Systemic alkalosis and use of a wrong IV fluid
  • Pseudohypokalemia (mainly due to poor sampling technique, especially upstream of IV fluid administration site)
  • Gitelman's syndrome
Symptoms
  • Fatigue
  • Thirst
  • Polyuria
  • Muscle weakness
  • Tetany
  • Paralytic ileus
  • Low serum chloride
  • Raised serum bicarbonate
  • Cardiac arrhythmias
  • ST segment depression and appearance of V waves on ECG
Diagnosis
  • Urea & Electrolyte
  • ECG
Differential
  • Refer to the causes of hyperkalemia that are listed above
Prevention
  • Management of underlying cause
Management
  • Management of underlying cause.
  • Give oral potassium tablets for patients with mild hypokalemia who can take oral medicines.
  • If the potassium serum levels < 3.5mmol/L, give SLOW potassium infusion diluted in 500 - 1000mL of IV fluid at a rate NOT exceeding 25mmol/hr. (Max. 80mmol/24hrs). REMEMBER that potassium IV bolus can cause a cardiac arrest! ALSO monitor serum potassium levels at least 1-2 times as a risk mitigation for a possible hyperkalemia.
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