Renal System >
Hypokalaemia
“A low serum potassium of <3.5mmol/L”
Risk Factors
- Eating Disorders
- AIDS
- Alcoholism
- Bariatric Surgery
Aetiology
- Increased Potassium uptake
- Increased Potassium excretion
- Decreased Potassium intake
- Increased Potassium shift from extracellular to intracellular
Pathophysiology
- Increased Potassium Excretion (loss)
- Drugs – diuretics (thiazides, loop), laxatives, glucocorticoids, fludrocortisone, penicillin, amphotericin, aminoglycosides
- GI losses – diarrhoea, vomiting, ileostomy, intestinal fistula
- Renal – renal tubular acidosis, diuretics, increased mineralocorticoid activity, polyuria, dialysis
- Endocrine disorders – hyperaldosteronism, Cushing’s syndrome
- Increased Potassium Uptake
- Insulin/glucose therapy
- Increase in beta-adrenergic activity e.g. salbutamol, theophylline, head injury
- Metabolic alkalosis
- Hypothermia
- Increased blood cell production
- Toxins
- Decreased Potassium Intake
- Diet
- Increased sweat loss – Magnesium depletion associated with increased renal potassium loss
Clinical Presentation
- Most patients asymptomatic and symptoms are non-specific (muscular/cardiac)
- Nervous system – cells are unable to become depolarised due to increased RMP (flaccid paralysis, weakness, muscle cramps)
- Constipation
- Respiratory difficulties
Investigations
- Bloods:
- Urea and Electrolytes – Creatinine ratio
- Potassium Levels – Check multiple values
- Imaging: n/a
- Special:
- Urinary Potassium
- To establish urinary loss vs transcellular shift
- >30mmol = inability of kidney to concentrate potassium
- ECG
- ST segment depression
- T wave flattering
- U waves
- Urinary Potassium

Management
- Mild Hypokalaemia
- Potassium supplements
- Potassium-sparing diuretics (Spironolactone)
- Severe Hypokalaemia
- Oral and IV KCl administration with normal saline at 10mmol/hr
Complications
- Cardiac Arrhythmias
- Rhabdomyolysis
- Ascending Paralysis