Hypokalaemia Flashcards
What are the main differential diagnoses of hypokalaemia?
- Diuretic therapy
- ß-agonist treatment
- Vomiting
- Excessive faecal loss
- Primary hyperaldosteronism
- Renal tubular defect
What suggests that diuretic therapy is the cause of hyperkalaemia?
Patient taking thiazide or loop diuretics
What confirms that diuretic therapy is the cause of hypokalaemia?
Normal potassium after stopping diuretic
How is hypokalaemia caused by diuretic therapy managed?
Stop suspected cause, with or without potassium supplements
What suggests that ß-agonist treatment is the cause of hypokalaemia?
Taking high doses ß-agonist, usually in a nebuliser for acute asthmatic attack in hospital
What confirms that ß-agonist treatment is the cause of hypokalaemia?
Normal potassium after stopping the drug
What suggests that vomiting is the cause of hypokalaemia?
History of severe vomiting with poor fluid intake
What confirms that vomiting is the cause of hypokalaemia?
Normal potassium without subsequent need for replacement when cause of vomiting is treated
How is hypokalaemia caused by vomiting managed?
Depending on severity, replacement of fluids and electrolytes, correction of acid-base imbalance, and dealing with specific underlying causes
What may cause increased faecal loss of potassium?
- Chronic diarrhoea
- Purgative abuse
- Intestinal fistula
- Villous adenoma of rectum
What suggests that increased faecal loss is the cause of hypokalaemia?
History of severe diarrhoea or mucous loss
How is it confimed that increased faecal loss is the cause of hypokalaemia?
Normal potassium without any need for further replacement when the cause is treated
How is hypokalaemia caused by increased faecal loss managed?
- Oral potassium supplements if not dehydrated, or potassium IV with IV fluid replacement if they are dehydrated
- Treatment of cause
What might cause primary hyperaldosteronism?
- Adrenal hyperplasia
- Conn’s syndrome with adrenal tumour
What suggests that hypokalaemia is caused by primary hyperaldosteronism?
- Normal fluid intake
- Increased BP
- Decreased serum potassium
