Electrolyte abnormalities

Question 1

What are normal K+ levels?

Answer 1

3.5-5 mmol/L

Question 2

What level of K+ is considered concerning hyperkalaemia?

Answer 2

6.5 mmol/L

Question 3

Outline common causes of hyperkalaemia.

Answer 3

Renal - CKD with diet rich in K+, AKI
Drugs - amiloride, spironolactone, ACE-I,NSAIDs
Metabolic - hypoaldosteronism (inc Addisons)
Burns
Rhabdomyolysis
Metabolic acidosis
Massive blood transfusion
Excess K+ therapy
Artifactual result

Question 4

Explain how you might get raised K+ as an artifactual result?

Answer 4

Haemolysis - difficult venepuncture
Thrombocytosis - K+ leaks from platelets during clotting
Delayed analysis - leaks from RBCs

Question 5

What are the risks of hyperkalaemia?

Answer 5

Myocardial hyperexcitablity leading to life threatening arrhythmias such as ventricular fibrillation and cardiac arrest

Question 6

What ECG changes are associated with hyperkalaemia?

Answer 6

Tall 'tented' T waves
PR lengthening 
Prolonged QRS
Slurring of ST segment
Flat or absent P waves
Sine wave

Question 7

What is the emergency treatment of hyperkalaemia to stabilise the heart?

Answer 7

Calcium gluconate

10ml of 10% over 5-10 mins

Question 8

What is the treatment to cause intracellular shift of K+?

Answer 8

IV Insulin/dextrose 
Salbutamol high dose - watch for tachycardia
Sodium bicarbonate (only if acidotic)

Question 9

What treatment is used to eliminate K+ from the body?

Answer 9

Calcium resonium - binds K+ in gut to decrease reabsorption
Furosemide
Dialysis

Question 10

What level of hypokalaemia requires urgent treatment?

Answer 10

K+ < 2.5 mmol/L

Question 11

What are symptoms of hypokalaemia?

Answer 11

Fatigue
Constipation,
Muscle weakness + hypotonia
Palpitation (arrhythmias)
Worsened glucose control in diabetics
Hypertension

Question 12

What are the causes of hypokalaemia?

Answer 12

GI losses - diarrhoea, vomiting, ileostomy, laxatives, fistula
Low diet intake
Renal losses - diuretics, liquorice, steroids
Metabolic - Cushing’s syndrome, Conn’s syndrome,
Alkalosis

Question 13

What other element often needs normalising in order to increase K+?

Answer 13

Magnesium

Question 14

What ECG changes are associated with hypokalaemia?

Answer 14

Small/inverted T wave
U wave (after T)
PR lengthened
ST depression

Question 15

What is the treatment of hypokalaemia?

Answer 15

Replace magnesium
>2.5mmol/L and no symptoms: oral K+ (Sando-K) and repeat bloods in 3 days

< 2.5 mmol/L or symptoms: IV K+ cautiously

Question 16

How is IV K+ given?

Answer 16

Usually with 0.9% sodium chloride (avoid dextrose as further induces hypokalaemia)
No more than 20mmol/hour
No more than 40mmol/L

Question 17

What features might make you suspect Conn’s syndrome?

Answer 17

Hypertensive
Hypokalaemia
Hypernatraemia
Patient not taking diuretics