Hyperkalaemia

Question 1

Normal K level

Answer 1

3.5 to 5.5 mmol/L

Question 2

Regulating factors of plasma K level

Answer 2

• Aldosterone
• Acid-base balance
• Insulin levels

Question 3

Foods that are high in potassium

Answer 3

• Salt substitutes = K salts (i.e. contain potassium rather than sodium)
• Banana
• Orange
• Kiwi fruit
• Avocado
• Spinach
• Tomato

Question 4

Hyperkalaemia >>> Associated acid-base disorder

Answer 4

Metabolic acidosis

(In some cases, metabolic acidosis has hypoklaemia with it)

Question 5

How is metabolic acidosis associated with hyperkalaemia?

Answer 5

• In the DCT >>> in the cell membrane >>> H⁺ and K⁺ ions compete with each other >>> for exchange with Na⁺
• So, when metabolic acidosis (high H⁺) >>> K gets less chance to exchange with Na in DCT >>> more K remains in blood >>> Hyperkalaemia
• And, vice-versa, when hyperkalaemia (high K) in blood >>> fewer H ions can enter the cells >>> metabolic acidosis
• So, high H⁺ is proportional to high K⁺

Question 6

Causes of hyperkalaemia

Answer 6

• First exclude pseudo-hyperkalaemia (Recheck a fresh sample)
• Acute renal failure (also CRF)
• Rhabdomyolysis (can lead to acute renal failure)
• Drugs: ABCDE Heparin
  
  • ACE inhibitors, ARBs, Aldactone
  • Beta blocker
  • Cytotoxic agents (>>> Tumour lysis syndrome), Ciclosporin
  • Digoxin
  • Eplerenone (Spironolactone: K-sparing diuretics)
  • Heparin (UFH and LMWH) (By inhibition of aldosterone secretion)
• Metabolic acidosis
• Massive blood transfusion
• Addison’s disease
• Insulin insufficiency

Question 7

Pseudohyperkalaemia is known to be associated with - ?

Answer 7

Essential thrombocytosis (ET)

Question 8

Drug causes of hyperkalaemia

Answer 8

Drugs: ABCDE Heparin

• ACE inhibitors, ARBs, Aldactone
• Beta blockers
• Cytotoxic agents (>>> Tumour lysis syndrome), Ciclosporin
• Digoxin
• Eplerenone (Spironolactone: K-sparing diuretics)
• Heparin (UFH and LMWH) (By inhibition of aldosterone secretion)

Question 9

Heparin (UFH and LMWH) >>> how do they cause hyperkalaemia?

Answer 9

They inhibit aldosterone secretion >>> hypoaldosteronism >>> hyperkalaemia

Question 10

Beta blockers >>> how do they cause hyperkalaemia?

Answer 10

They interfere with potassium transport into cells → hyperkalaemia

Question 11

Hyperkalaemia: Features

Answer 11

• General fatures >>>
  
  • Anxiety
  • Fatigue
• Cardiac features >>>
  
  • Mild chest pain (on-off)
  • Palpitations
  • Bradycardia
  • Hypotension
  • ECG changes
  • Life threatening arrythmias (In higher levels & if untreated)
• Neuromuscular features >>>
  
  • Numbness tingling
  • Muscle weakness
  • Muscle fatigue
• Gastrointestinal features >>>
  
  • Nausea, vomiting​

Question 12

Hyperkalaemia: ECG changes

Answer 12

• P wave >>> Small P wave (or flattened P wave)
• QRS complex >>> Widened QRS
• T wave >>> Tall tented T wave (More suggestive)
• Sinus bradycardia

​Later leading to >>>

• Sinusoidal pattern
• Life threatening (ventricular) arrythmia
• Asystole

Question 13

Relation of K level with Beta-blockers and beta-agonists

Answer 13

• Beta blockers interfere with K transport into cells >>> raises K level (A cause of hyperkalaemia)
  
  • e.g. Atenolol, Metoprolol, Bisoprolol, Esmolol etc.
• Beta-agonists help with K transport into cells >>> lowers K level (An emergency treatment of hyperkalaemia)
  
  • e.g. Salbutamol

Question 14

Beta blocker use in renal failure

Answer 14

Contraindicated

As both cause hyperkalaemia >>> Beta blocker use in renal failure can potentially cause severe hyperkalaemia

Question 15

Surgery in CRF patient

Answer 15

• Postpone surgery until serum K is below 5.5 mmol/l (As CRF has hyperkalaemia)
• Monitor K immediately after surgery
• Monitor again 4-6 hours later

Question 16

Management of hyperkalaemia

Answer 16

• First step: Removal of all cause to prevent cardiac arrest
• First priority treatment: Stabilisation of the cardiac membrane
  
  • IV calcium gluconate 10% 10ml over 10mins
    
    • If question asks 1st line treatment / ECG not done yet / ECG done + abnormal ECG
    • this is also a treatment of hypocalcaemia
• Second step treatment: Short-term shift of K from ECF to ICF (within cells)
  
  • 15U Actrapid insulins in 50% 50mol dextrose IV
    
    • If question asks Tx after Ca.gluconate / treatment to lower serum K/ mentioned normal ECG
  • Nebulised salbutamol
    
    • Sometimes as emergency Tx
• Third step: Removal of extra K from the body
  
  • Calcium resonium (orally or enema)
  • Loop diuretics
  • Dialysis

Question 17

What is the first priority in the management of hyperkalaemia?

Answer 17

Stabilisation of the cardiac membrane > by >

• IV calcium gluconate 10% 10ml over 10mins

Question 18

Aim of treatment with calcium gluconate

Answer 18

Stabilisation of the cardiac membrane

Question 19

IV calcium gluconate >>> mechanism

Answer 19

• It acts within minutes AND
• It works by >>> raising the depolarization threshold for myocytes (>>> cardiac membranes are stabilised)

Question 20

First line treatment in hyperkalaemia

Answer 20

IV calcium gluconate 10% 10ml over 10mins

Question 21

Patient with hyperkalaemia (K >5.5mmol/L) + Abnormal ECG: flattened P wave, peaked T wave + others >>> 1^st Treatment

Answer 21

IV calcium gluconate 10% 10ml over 10mins

Question 22

Patient with hyperkalaemia (K >5.5mmol/L) + symptoms + NO ECG mentioned or done + others >>> 1st Treatment

Answer 22

IV calcium gluconate 10% 10ml over 10mins

Question 23

Patient with hyperkalaemia + already given calcium gluconate >>> next treatment

Answer 23

15U Actrapid insulins in 50% 50mol dextrose IV

Question 24

Treatments of hyperkalaemia that reduces serum K level by short-term shift of K from ECF to ICF (within cells)

Answer 24

• 15U Actrapid insulins in 50% 50mol dextrose IV
• Salbutamol nebuliser
• NaHCO₃ IV (debatable, can worse volume overload esp. in renal imp and pulmonary oedema)

Question 25

Aim of treatment with combined insulin + dextrose infusion in hyperkalaemia management

Answer 25

Short-term shift of K from ECF to ICF (within cells)

Question 26

Aim of treatment with ‘salbutamol nebuliser’ in hyperkalaemia management

Answer 26

It reduces serum K level by short-term shift of K from ECF to ICF (within cells)

Question 27

Patient with hyperkalaemia >>> treatment to lower serum K level

Answer 27

15U Actrapid insulins in 50% 50mol dextrose IV

Question 28

Patient with hyperkalaemia + normal ECG + others >>> (First) Treatment

Answer 28

15U Actrapid insulins in 50% 50mol dextrose IV

Question 29

Patient with hyperkalaemia + needs emergency treatment >>> Treatment

Answer 29

Nebulised salbutamol

Question 30

Patient with hyperkalaemia + given treatment with calcium gluconate and “insulin+dextrose” (or those are not available) >>> 3rd line treatment

Answer 30

• Calcium resonium (oral or enema)
• Loop diuretics
• in some cases >>> dialysis

Question 31

Treatment of hyperkalaemia that removes K from the body

Answer 31

• Calcium resonium (oral or enema)
• Loop diuretics
• Dialysis

Question 32

Aim of treatment with ‘Calcium resonium (oral or enema)’ in hyperkalaemia management

Answer 32

Removal of K from the body​

Question 33

Calcium resonium >>> mechanism

Answer 33

• It is an ion exchange resin
• When taken orally → prevents potassium absorption from the diet → depletes the body potassium level
• It takes at least 24-48 hours to have an effect
• It is NOT suitable as an emergency treatment

Question 34

Aim of treatment with ‘loop diuretics’ in hyperkalaemia management

Answer 34

Removal of K from the body (by excretion)