Hypokalaemia

Question 1

Hypokalaemia >>> acid-base disorder

Answer 1

Metabolic alkalosis OR metabolic acidosis (both are possible)

Question 2

Hypokalaemia + metabolic alkalosis >>> causes

Answer 2

• Vomiting
  
  • ​​Peptic ulcer >>> pyloric stenosis
  • Any cause of vomiting
• ​Aspiration
  
  • ​Nasogastric suction, gastric aspiration etc.
• ​Extra intake of >
  
  • ​Diuretics
  • ​Liquorice
  • Carbenoxolone
• Diseases >
  
  • ​Hypokalaemia (due to any cause)
  • Primary hyperaldosteronism (Or Conn’s syndrome)
  • Cushing’s syndrome
  • Congenital or inherited >
    
    • CAH (Congenital Adrenal Hyperplasia) (AR)
    • Bartter’s syndrome (AR)

​(All the causes of metabolic alkalosis are included here; As all the causes have associated hypokalaemia)

Question 3

Hypokalaemia + metabolic acidosis >>> causes

Answer 3

• Diarrhoea (> hyperchloraemia, normal anion gap)
• RTA (Renal tubular acidosis) type 1,2,3 (> hyperchloraemia, normal anion gap)
• Acetozolamide (> hyperchloraemia, normal anion gap)
• Partially treated DKA (DKA has a raised anion gap)

​​Except these 4, rest of the common causes of metabolic acidosis are related to hyperkalaemia

Type 4 RTA has hyperkalaemia + metabolic acidosis, normal anion gap

Question 4

Hypokalaemia >>> ECG features

Answer 4

• PR >>> Prolonged PR interval
• QT >>> Long QT
• ST >>> ST depression
• T >>> Small or absent T wave (occasionally inversion)
• Extra >>> U wave

​Mnemonnic: U have no Pot (ST), no T; but a long PR and long QT

Question 5

At which K level, do ECG features of hypokalaemia develop?

Answer 5

<2.7mmol/L

Question 6

ECG features: Hypokalaemia vs Hypomagnesaemia

Answer 6

​Hypokalaemia has >>>

• PR >>> Prolonged PR interval
• QT >>> Long QT
• ST >>> ST depression
• T >>> Small or absent T wave (occasionally inversion)
• U wave

​Hypomagnesaemia has all the same features as above; but NO U wave

Question 7

U wave in ECG >>> Diagnosis

OR U wave is only present in- ?

Answer 7

Hypokalaemia

Question 8

Which electrolyte deficiency can cause hypokalaemia?

Answer 8

• Mg (Magnesium) deficiency (hypomagnesaemia)
• In such cases, try to normalise the Mg level first;
  
  • ​​because, normalising K level may be difficult until the Mg deficiency has been corrected

Question 9

Approx. a drop of 1mmol in serum K is equivalent to >>> ?body loss

Answer 9

A total body loss of 200mmol of K