Hypokalaemia

Question 1

Define hypokalaemia

Answer 1

Serum potassium concentration < 3.5 mmol/L

Question 2

What kind of symptoms do the majority of patients with hypokalaemia have

Answer 2

Most cases are mild and patients are asymptomatic

Question 3

There is a potential for hypokalaemia to be life-threatening condition.

What potentially can occur to make it life-threatening?

Answer 3

Cardiac arrhythmias

Question 4

There are multiple causes of hypokalaemia.

The causes can be broken down into 3 major category? ​

Answer 4

Inadequate intake

Increased excretion

Transcellular shift

Question 5

What patient group is hypokalaemia commonly seen in?

Answer 5

Among the elderly and those with reduced oral intake

Question 6

Give 4 examples of causes that can result in hypokalaemia secondary to inadequate potassium intake

Answer 6

Eating disorders: bulimia, anorexia nervosa, alcoholism

Poor diet

Systemic illness and dental problems

Inadequate potassium in feed or fluid replacement (IVF, NG feed, TPN)

Question 7

Give two examples of causes that can result in hypokalaemia secondary to increased potassium excretion

Answer 7

Secondary to diuretics e.g. loop, thiazide

Gastrointestinal losses e.g. diarrhoea and/or vomiting

Question 8

Give examples of causes that can result in hypokalaemia secondary to transcellular shift in potassium

Answer 8

Potassium is predominantly an intracellular cation, but certain conditions increase the chance of potassium shifting from the extracellular to intracellular space.

Alkalosis, insulin and beta-adrenergic receptors e.g. salbutamol, enhance the intracellular movement of potassium

Question 9

Name the investigations used to diagnosis hypokalaemia

Answer 9

Bloods (diagnosis by anything that detects serum potassium)

• U&Es
• VBG/ABG
• Urinary potassium

Other

• ECG - checking for cardiac arrhythmias

Question 10

What are the 4 ECG changes associated with hypokalaemia

Answer 10

Flat T waves

ST depression

Prominent U waves – small deflection that occurs following the T waves, typically in the same direction

Prolonged PR

Question 11

What is the mainstay of hypokalaemia treatment

Answer 11

Potassium replacement

Question 12

What must be done alongside IV potassium replacement in the treatment of hypokalaemia

Answer 12

Continuous cardiac monitoring is required for early arrhythmia recognition

Question 13

Define mild hypokalaemia

Answer 13

3 - 3.4 mmol/L

Question 14

Define moderate hypokalaemia

Answer 14

2.5 -2.9 mmol/L

Question 15

For mild/moderate hypokalaemia in patients with no ECG changes or asymptomatic.

What type of potassium replacement is preferred

Answer 15

Oral

Question 16

In what patient group should IV potassium replacement be considered as the 1st line therapy to treat hypokalaemia

Answer 16

Mild/moderate hypokalaemia with symptoms or ECG changes

Severe hypokalaemia

Question 17

What is the cut off potassium for severe hypokalaemia

Answer 17

<2.5 mmol/L

Question 18

Give an example of oral potassium replacement that can be used to manage hypokalaemia

Answer 18

SANDO-K (potassium chloride with potassium bicarbonate)

Question 19

Give an example of IV potassium replacement that can be used to manage hypokalaemia

Answer 19

1L 0.9% saline containing 40mmol potassium chloride