Saturday 20 November 2010

MRCP revision battle 55.2: Hypokalaemia

Hypokalaemia is defined as K <3.5mmol; if <2.5mmol it is severe.


Symptoms/signs include:
  • muscle weakness
  • hypotonia
  • cramps
  • tetany
  • worsening of dig toxicity
  • cardiac arrhythmias

ECG may show:
  • small/inverted T waves
  • U waves
  • long PR
  • depressed ST

Causes of hypokalaemia


Low K with hypertension
  • raised plasma renin
    • Cushings
    • renin-secreting tumour
  • low plasma renin

Low K without hypertension


On to cryoglobulins...