Introduction

• Abnormally low potassium concentration in the blood.
• Hypokalemia is a manifestation of disease NOT A DIAGNOSIS.
• Cause: excessive potassium loss through vomiting or urinary sytem, or reduced dietary intake (anorexia).
• Signs: muscle weakness, ileus.
• Diagnosis: laboratory measurement of potassium.
• Treatment: manage underlying cause and potassium supplementation.
• Prognosis: good if condition recognized and managed appropriately.

Pathogenesis

Etiology

• Gastrointestinal:
  • Vomiting Vomiting.
  • Diarrhea Diarrhea: chronic.
• Renal:
  • Renal failure Kidney: chronic kidney disease (CKD).
  • Post-obstructive renal disease Urethra: obstruction.
  • Chronic pyelonephritis Kidney: pyelonephritis.
  • Diuretic therapy eg frusemide Furosemide.
  • Amphotericin B Amphotericin B.
  • Hyperaldosteronism (nephrotic syndrome Nephrotic syndrome , heart failure Heart: congestive heart failure , liver failure Liver: cirrhosis ).
• Metabolic:
  • Diabetic ketoacidosis Diabetic ketoacidosis.
  • Metabolic alkalosis (heat exhaustion Hyperthermia ).
  • Insulinoma Pancreas: neoplasia: insulinoma or insulin administration.
• Burns.
• 
  
  Inadequate potassium replacement
• Anorexia.
• Potassium deficient intravenous fluid therapy Fluid therapy.

Predisposing factors

• Polyuria increases urinary loss of potassium.
• Anorexia reduces dietary intake.

Pathophysiology

• Vast majority (95%) of body potassium is present intracellularly.
• Serum potassium concentration may not be an accurate reflection of total body stores.
• Intestinal ileus may predispose to hypokalemia (pooling of potassium rich intestinal secretions within intestinal lumen).
• Hypokalemia may → ileus.
• In the recovery from gastrointestinal surgery particulary where vomiting has been a pre-operative feature, eg intussusception Intussusception or intestinal obstruction Intestine: obstruction serum potassium concentrations should be measured regularly and supplementation given where necessary to ensure rapid post-operative return to normal function.

Timecourse

• Usually insidious onset over a number of days.

Diagnosis

Treatment

Outcomes