Hypokalaemia



Background

Vomit contains relatively little potassium but severe vomiting causes hypochloraemic alkalosis due to loss of chloride and acid, which causes severe renal wasting of potassium and an intracellular shift of potassium.

Liquid stool has 10-50mmol l-1 - hypokalaemia early in diarrhoea.

Renal loss K+ most often due to diuretics. Commonest is seen with large doses diuretics with secondary hyperaldosteronism as seen in heart failure, cirrhosis and nephrotic syndrome.

Other causes are primary hyperaldosteronism (Conn's) and Cushing's syndromes.


Aetiology

Intracellular shifts

  • Alkalosis, Hi dose insulin, Periodic paralysis

GI loss

  • D & V
  • Ileostomy
  • Purgative abuse
  • Eating disorders
  • Villous adenoma of rectum

Renal wasting

  • Diuresis - drugs or osmotic ( Hyperglycaemia, Uraemia )
  • RTA
  • Hyperaldosteronism - Primary or secondary
    Cushing’s
  • Bartter's synd
  • Drugs - Liquorice, carbenoxolone, gentamicin XS
  • Leukaemia

Hypokalaemia
hypokalaemia

Key Clinical Features

Severe hypokalaemia < 2.5 mmol l-1 

  • dysrhythmias, dig toxicity and fasciculations

Moderate

  • muscle weakness, absent reflexes, gut ileus
  • reduced renal conc ability (Nephrogenic diabetes insipidus) with Na+ retention 

Treatment and management

  • Treatment PO replacement (bananas, orange juice or if long term treatment required - Sando K tablets)
  • IV max potassium = 20mmol / hour with cardiac monitor and hourly U&E

Content by Dr Íomhar O' Sullivan 13/07/2004. Reviewed by Dr ÍOS 19/07/2005, 27/05/2006, 28/03/2007. Last review Dr ÍOS 4/12/18.