Hypokalaemia

Question 1

Define Hypokalaemia

Answer 1

A serum K+ concentration < 3.5 mmol/L

Question 2

Mild hypokalaemia

Answer 2

3.0 - 3.5

Question 3

Moderate hypokalaemia

Answer 3

2.5 - 3.0

Question 4

Severe Hypokalaemia

Answer 4

< 2.5

Question 5

Renal potassium loss causes

Answer 5

Diuretics (loops and thiazides)
Hypomagnesaemia
Osmotic diuresis
Mineralocorticoid excess (Conn’s syndrome, Cushing’s syndrome, congenital adrenal hyperplasia)
Renal tubular acidosis types I and II
Renal tubular disorders (Bartter, Gitelman and Liddle syndrome)

Question 6

GI potassium loss

Answer 6

Diarrhoea and vomiting
Laxative abuse
Fistulae
High output ileostomy
Eating disorders with chronic purging

Question 7

Potassium redistributed into cells

Answer 7

Alkalosis
Refeeding syndrome
Insulin overdose
Beta-agonists (e.g. salbutamol) - shifting intracellularly
Theophylline or aminophylline
Hypokalaemic periodic paralysis

Question 8

Hypokalaemia Sx

Answer 8

Muscle cramping and pain
Fatigue
Weakness

Question 9

Hypokalaemia Ix

Answer 9

1. VBG - K+ level, lactate, acid-base status
2. ECG
3. BT - UEs, Mg, Bone profile, CK

Question 10

Hypokalaemia ECG findings

Answer 10

• flattened T wave / T wave inversion
• U waves (deflection immediately following the T wave)
• ST depression

Question 11

Correction of which ion allow rapid correction of hypokalaemia

Answer 11

Mg

Question 12

Mild (3.0-3.5) Hypokalaemia Mx

Answer 12

• Dietary supplement
• Sando-K TT TDS

Question 13

Moderate (2.5-3.0) hypokalaemia Mx

Answer 13

• Sando-K TT TDS
• IV KCl 20-40 mmol

Question 14

Severe (< 2.5) hypokalaemia Mx

Answer 14

• IV potassium chloride 40mmol in 1L 0.9% Saline over 4 hrs
• IV Mg

IV K+ never as a bolus

Question 15

Max. IV K+ replacement dosage/rate

Answer 15

10mmol/hour