Hypokalaemia

• Symptoms:
  • Generalised fatigue, weakness, ileus, atrial arrhythmia, acute renal insufficiency, rhabdomyolysis (K < 2.5), flaccid paralysis, respiratory compromise (K < 2)
• ECG changes:
  • Increased P wave amplitude
  • ST depression
  • T wave flattening/inversion
  • U waves
• Causes:
  • Renal losses
  • Extrarenal losses – vomiting, NG tubes, diarrhoea, fistula, alkalosis, catecholamine secretion
  • Medications – CHF medications, diuretics, insulin
  • Hyperthyroidism
  • Hyperaldosteronism, renin-secreting tumours
• Treatment:
  • IV or oral replacement. Rate of >10 mmol/hr IV needs cardiac monitoring.
  • Magnesium level should be monitored → hypomagnesemia can produce refractory hypokalaemia due to failure of ATP Na/K pump.