Hyperkalaemia

Question 1

What are the causes of Hyperkalaemia?

Answer 1

Reduced renal excretion – CKD, AKI, Renal Tubular Acidosis, Diuretics, Adrenal Failure (Addison’s), Ace inhibitors
Increased input of Potassium – Inappropriate use of K+ containing fluids or K+ supplements
A shift from intracellular to extracellular – Acidosis, Rhabdomyolysis, Digoxin Toxicity

Question 2

What will you find on a history of Hyperkalaemia?

Answer 2

Symptoms:
Weakness
Chest pain
Palpitations
Light headedness
Paralysis

Risk Factors:
renal failure
Muscle trauma - Rhabdomyolysis
Diabetic - DKA can cause it
adrenal insufficiency
Use of potassium-sparing diuretics or potassium supplements
Addison’s - weight loss, fatigue, excessive skin pigmentation, cold intolerance, hypotension

Question 3

What will you find on examination of a patient with Hyperkalaemia?

Answer 3

End of the bed:
Muscle weakness
Depressed or absent deep tendon reflexes
Muscle tenderness in rhabdomyolysis
Chest:
Tachypnoea – Respiratory muscle weakness
Hands:
Bradycardia due to heart block

Question 4

What investigations will you order in Hyperkalaemia?

Answer 4

Bedside:
ECG - Flat P Waves, tented T waves, wide QRS, Long PR interval, Bradycardia can cause V.Fib or Cardiac Arrest
Urinalysis - To rule out rhabdomyolysis (Raised Myoglobin) and looking for any proteinuria or haematuria that may indicate renal failure
24 hour urinate collection – Measuring output volume and levels of K+ in the urine, low levels indicate the Kidneys are not functioning appropriately
Capillary glucose and ketones – To rule out DKA

Bloods:
U&E - Will show hyperkalaemia (causes of false positives include haemolysis of blood sample, K+ contamination of samples if wrong order of bloods taken)
Calcium
FBC – Normocytic anaemia indicating a haemolytic anaemia (rhabdomyolysis)
Creatinine Kinase - To rule out rhabdomyolysis
Cortisol and aldosterone levels - Ruling out Addison’s
ABG - Rules out metabolic acidosis

Special Tests:
Urine pH – To rule out Renal Tubular Acidosis

Question 5

What is the treatment of Hyperkalaemia?

Answer 5

Resuscitation:
A-E approach
Get IV Access/Give O2 to maintain sats of 94+ Continuous 12 lead ECG monitoring
Assessment with AMPLE history and brief examination
Get help - Medical reg on call
Frequent Observations - Constant or 15 minutely

Medical:
Severe: Symptomatic, ECG changes or >6.5mmol/l
Calcium Gluconate 10ml 10% IV over 5 mins (protecting the heart).
Actrapid insulin 10 units in 50ml 20% dextrose over 30 mins with Nebulised salbutamol (forces K+ into cells)
Calcium Resonium (Binds to K+ in gut and stops absorption, can be given orally, or as enema if NBM)
Haemodialysis if not improving
Treat the underlying cause

Mild:
Calcium Resonium
Treat the underlying cause