Hyperkalaemia

Question 1

Conditions that cause hyperkalaemia:

Answer 1

AKI
CKD
Rhabdomyolysis
Adrenal insufficiency
Tumour lysis syndrome

Question 2

Medications that can cause hyperkalaemia

Answer 2

• aldosterone antagnoists (spironolactone/ eplerenone)
• ACE inhibitors
• ARBs
• NSAIDs
• Potassium supplements

Question 3

What can cause a falsely elevated potassium on U&Es?

Answer 3

Haemolysis during sampling

Lab may alert you to possible haemolysis - require a repeat sample to confirm

Question 4

How is hyperkalaemia diagnosed?

Answer 4

U&Es

Also pay attention to creatinine, urea and eGFR - as acute/chronic renal failure important to discuss (consider haemodialysis)

Question 5

ECG signs in hyperkalaemia:

Answer 5

Tall peaked T waves
Flattening or absence of P waves
Broad QRS complexes

Question 6

When is a patient indicated for an ECG:

Answer 6

ECG is required in all patients with a potassium above 6 mmol/L.

Question 7

Treatment thresholds for hyperkalaemia:

Answer 7

Patients with potassium ≤ 6 mmol/L with otherwise stable renal function don’t need urgent treatment and may just require a change in diet and medications (i.e. stopping their spironolactone or ACE inhibitor).

Patients with potassium ≥ 6 mmol/L and ECG changes need urgent treatment.

Patients with a potassium ≥ 6.5 mmol/L regardless of the ECG need urgent treatment.

Question 8

Mainstay management of patient with hyperkalaemia:

Answer 8

insulin and dextrose infusion + IV calcium gluconate:

Insulin (e.g. actrapid 10 units) and dextrose (e.g. 50mls of 50%) :
drives carbohydrates into cells and takes potassium with it, reducing the blood potassium.

Calcium gluconate:
stabilises the cardiac muscle cells and reduces the risk of arrhythmias.

Question 9

Other options for lowering serum potassium:

Answer 9

Nebulised salbutamol:
temporarily drives potassium into cells.

IV fluids:
can be used to increase urine output, which encourages potassium loss from the kidneys (but don’t fluid overload patients with renal failure).

Oral calcium resonium:
draws potassium out of the gut and into the stools. It works slowly and is suitable for milder cases of hyperkalaemia.

Sodium bicarbonate (IV or oral):
may be considered on the advice of a renal specialist in acidotic patients with renal failure. It drives potassium into cells as the acidosis is corrected.

Dialysis:
may be required in severe or persistent cases associated with renal failure.