Clinical Chemistry 2 - Potassium Flashcards
The concentrations of potassium in the ECF tend to vary in association with which other ion?
Hydrogen
A plasma potassium level of greater than what is a medical emergency?
> 6.5mmol/l
If a patient has hyperkalaemia, why is urgent treatment indicated?
There is a risk of ventricular fibrillation (and cardiac arrest)
What are some concerning signs and symptoms in someone with hyperkalaemia?
Irregular pulse/palpitations, chest pain, muscle weakness, light-headedness
What happens to T waves in an ECG of hyperkalaemia?
Tall, tented T waves
What happens to P waves in an ECG of hyperkalaemia?
Small or absent P waves
What happens to the QRS complex in an ECG of hyperkalaemia?
Wide
Which acid-base disorder is associated with hyperkalaemia?
Metabolic acidosis
What are some drugs which may cause hyperkalaemia?
Potassium-sparing diuretics, ACE inhibitors/ARBs
How is non-urgent hyperkalaemia managed?
Treat the underlying cause and review medications
What drug can be given to patients with non-urgent, long-term hyperkalaemia?
Calcium resonium (polystyrene sulfonate resin)
Calcium resonium (polystyrene sulfonate resin) brings down potassium levels over what time period?
A few days
When should hyperkalaemia be treated as an emergency, even if the level isn’t > 6.5mmol/l?
If there is any evidence of myocardial hyper-excitability
Which investigations should be performed immediately on someone with suspected hyperkalaemia?
ABG/VBG and ECG
How should the cardiac membrane be stabilised in someone with hyperkalaemia?
10ms 10% calcium gluconate
How should potassium be driven back into cells in someone with hyperkalaemia?
10 units Actrapid in 50mls 50% dextrose
Other than insulin and dextrose, what are some other medications which can drive potassium into cells?
Salbutamol and sodium bicarbonate
What is required if medical treatment fails to normalise the potassium level in someone with hyperkalaemia?
RRT
A plasma potassium level of less than what requires urgent treatment?
< 2.5mmol/l
Hypokalaemia exacerbates toxicity associated with which drug?
Digoxin
What drugs can be responsible for causing hypokalaemia?
Diuretics (non-potassium sparing)
What acid-base balance is associated with hypokalaemia?
Metabolic alkalosis
If a patient is on diuretics, what can be used as an indicator that hypokalaemia is longstanding?
High bicarbonate
Hypokalaemia goes hand in hand with which other electrolyte abnormality?
Hypomagnesaemia
Symptoms of hypokalaemia are rare. If they do occur, what may they include?
Muscle weakness, hypotonia/reflexia, palpitations, light-headedness, constipation
Hypokalaemia predisposes to which arrhythmias?
Ectopic beats, AV block, atrial and ventricular fibrillation
What happens to the PR interval on an ECG of someone with hypokalaemia?
Progressively lengthened
What happens to the ST segment on an ECG of someone with hypokalaemia?
Depressed
What happens to the T waves on an ECG of someone with hypokalaemia?
Flattened
What is the treatment of mild hypokalaemia (i.e. potassium > 2.5mmol/l, no symptoms)?
Oral potassium supplements
What is the treatment of severe hypokalaemia (i.e. potassium < 2.5mmol/l and/or dangerous symptoms)?
IV potassium supplementation
No more than how many mmol/l of potassium should be given in one hour?
20mmol
