Hypokalaemia (Long PRuSTt)

Question 1

Definition

Answer 1

< 3.5 mmol/L
< 2.5 mmol/L = EMERGENCY

Question 2

Aetiology

Answer 2

• Thiazides + loop diuretics - Na+ sparing, K+ excreting = BENDROFLUMETHIAZIDE (th), FUROSEMIDE (loop), Insulin, Salbutamol
• Renal tubular acidosis
• GI losses
• Increased ALDOSTERONE (CONNS)
• Decreased Intake

Question 3

Pathophysiology

Answer 3

K+ key for maintaining resting cell membrane potential
Low levels of K+ can affect smooth, skeletal and cardiac muscles are diminished

Question 4

Symptoms

Answer 4

Smooth muscle = constipation
Cardiac = arrhythmias + cardiac arrest
Skeletal = weakness, cramps, and flaccid paralysis
Resp muscles = resp depression

Question 5

Signs

Answer 5

Hypotonia
Hyporeflexia
Arrhythmias (Esp. AF)
Muscle paralysis + rhabdomyolysis

Question 6

Diagnosis

Answer 6

Plasma potassium -
- Mild: 3.0-3.5 mmol/L
- Moderate: 2.5-2.9 mmol/L
- Severe: <2.5 mmol/L or symptomatic
ECG:
- PR prolongation
- Prominent U waves
- ST depression
- Small, inverted T waves
Long PRu T
ST

Question 7

Treatment

Answer 7

Potassium IV/PO
Aldosterone antagonist (SPIRONOLACTONE)
Other electrolytes as required
Treat underlying cause