Mild hypokalaemia (low potassium in the blood), with potassium levels of 3.1-3.5 mmol/L, is probably the commonest electrolyte abnormality affecting hospitalised patients. In 5% of cases the potassium level is below 3.0 mmol/L, but even mild hypokalaemia can affect the heart rhythm. It’s commonly associated with the use of certain diuretics (water tablets) of the thiazide type in the elderly, and also dietary disorders such as anorexia, causing gastrointestinal fluid loss through persistent vomiting, diarrhoea or laxative abuse. Other risk factors include accompanying illness such as heart failure, alcoholism and nephrotic syndrome.
Mild forms are generally asymptomatic, but in more severe conditions (potassium below 3.0 mmol/L), symptoms include tiredness, weakness, muscle pain and constipation. When severe (below 2.5 mmol/L), serious neuromuscular problems occur: severe weakness and paralysis, respiratory failure, bowel…
