Hypokalaemia

Question 1

Define hypokalaemia

Answer 1

Low levels of potassium in the blood

Question 2

What is the epidemiology of hypokalaemia

Answer 2

• V rare: fewer than 1% of people who aren’t taking medication have a serum potassium of less than 3.5mmol/L
• Remember that potassium intake varies according to factors: age/sex/ethnic background/socioeconomic status

Question 3

Define the causes/risk factors of hypokalaemia

Answer 3

• Renal causes:
• High levels of aldosterone in kidneys
• Increased renal excretion: thiazides diuretics (Bendroflumethiazide) and loop diuretics (furosemide)
• Non renal causes: diarrhoea/laxative abuse and comiting

Also fasting and anorexia

Question 4

Define the pathology of hypokalaemia

Answer 4

• When there are low levels of K+, hyperpolarisation occurs in cardiac myocytes, decreasing their excitability
• Remember: due to increased leakage from ICF (as low K+ in ECF causes a water conc gradient out of the cell)

Question 5

Define the signs and symptoms of hypokalaemia

Answer 5

Symptoms

• Usually asymptomatic
• Muscle weakness
• Cramps
• Tetany
• Palpitations

Signs
- Respiratory depression

Question 6

What are the investigations and diagnosis for hypokalaemia

Answer 6

1. ) ECG:
   - flattened T-wave
   - extended U wave
   - Depressed ST segment
   - Long PR +QT
   - Rhyme: U have no Pot (K+) and no Tea but a long PR and long QT
2. ) U&E’s: Urine test can define difference between renal and non renal cause
   - Renal: high K+
   - Non renal: low K+
   - Serum K+ < 3.5mmol/L = hypokalaemia
   - Serum K+ < 2.5mmol/L = medical emergency

Question 7

What is the management and treatment for hypokalaemia

Answer 7

Mild to moderate:
-Oral potassium e.g. oral Sando-K and spironolactone (K+ sparing)

Severe:
- IV potassium with regular monitoring due to hyperkalaemia risk