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AIP: Acute confusional state > Hypo/hyperkalaemia > Flashcards

Hypo/hyperkalaemia Flashcards

1
Q

What is the definition of hyperkalaemia?

A

serum potassium concentration >5.5 mmol/L

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2
Q

What are 3 groups of causes of hyperkalaemia?

A
  1. Imapired excretion from the kidney
  2. Increased release from cells
  3. Pseudohyperkalaemia/ artefact
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3
Q

What are 10 causes of hyperkalaemia due to impaired excretion?

A
  1. AKI
  2. CKD
  3. ACE inhibitors
  4. Potassium sparing diuretics e.g. spironoclactone
  5. NSAIDs
  6. Heparin/ LMWH
  7. Ciclosporin
  8. High dose trimethoprim
  9. Hypoaldosteronism (e.g. renal tubular acidosis type 4)
  10. Addison’s disease
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4
Q

What are 7 causes of hyperkalaemia due to increased release from cells?

A
  1. Lactic acidosis
  2. Insulin deficiency
  3. Rhabdomyolysis
  4. Tumour lysis syndrome
  5. Massive haemolysis
  6. Digoxin toxicity (NB: this can be precipitated by hypokalaemia)
  7. Beta blockers
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5
Q

What are 4 causes of pseudohyperkalaemia/artefact causes of hyperkalaemia?

A
  1. Haemolysis (traumatic venepuncture, prolonged tourniquet use, fist clenching)
  2. Delayed analysis (K+ leaks out of red blood cells)
  3. Contamination with potassium EDTA anticoagulant in FBC bottles
  4. Thrombocytopenia (K+ leaks out of platelets during clotting)
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6
Q

What are 7 ECG changes in hyperkalaemia?

A
  1. Tall, tented T waves
  2. Broad QRS complexes
  3. Prolonged PR interval
  4. Flattened p waves
  5. Idioventricular rhythms
  6. sine wave paterns
  7. VF/ asystole
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7
Q

What are 4 aspects of management of hyperkaelamia?

A
  1. Give 10ml 10% calcium gluconate over 10 minutes - cardioprotective
  2. IV insulin: 10 units of Actrapid in 50ml of 50% dextrose
  3. Nebulised salbutamol
  4. Calcium resonium 15g orally (or rectally)
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8
Q

When should you treat for hyperkalaemia?

A

potassium >6.5 or any ECG changes

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9
Q

What is the mechanism of action of calcium gluconate when treating hyperkalaemia?

A

cardioprotective (does’t reverse hyperkalaemia)

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10
Q

What is the mechanism of IV insulin + dextrose infusion when treating hyperkalaemia?

A

causing intracellular shift of potassium - only transient (also need to treat underlying cause)

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11
Q

What is the mechanism of action of nebulised salbutamol to treat hyperkalaemia?

A

intracellular shift of potassium - transient

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12
Q

In addition to the 4 initial steps of management of hyperkalaemia, what are 3 further aspects of management?

A
  1. check contributing drugs e.g. ACEi, spironolactone
  2. Once initial measures completed, recheck U+Es and ECG and glucose
  3. Check urinary potassium
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13
Q

Why can heparin/ LMWH cause hyperkalaemia?

A

inhibits aldosterone release

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14
Q

What are 5 types of drugs which can cause hyperkalaemia?

A
  1. Potassium sparing diuretics e.g. spironolactone
  2. Angiotensin-converting enzyme inhibitors
  3. Angiotensin-II receptor blockers e.g. losartan
  4. Ciclosporin
  5. Heparin
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15
Q

Why is metabolic acidosis associated with hyperkalaemia?

A

hydrogen and potassium ions compete with each other for exchange with sodium ions across cell membranes and in the distal tubule

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16
Q

What are 7 foods that are high in potassium?

A
  1. Salt substitutes - i.e. contain potassium rather than sodium
  2. Bananas
  3. Oranges
  4. Kiwi fruit
  5. Avocado
  6. Spinach
  7. Tomatoes
17
Q

What is a type of drug which can potentially cause hyperkalaemia in patients with renal failure and why?

A

beta blockers - interfere with potassium transport into cells (hence why salbutamol, a beta agonist, can be used as emergency treatment)

18
Q

What is more effect, oral or rectal (enema) calcium resonium?

A

rectal - because potassium is secreted by the rectum

19
Q

How does calcium resonium work to treat hyperkalaemia?

A

it’s a resin that binds potassium in the gut to increase excretion in the rectum

20
Q

What is the management for persistent hyperkalaemia in patients with AKI when all other methods have failed?

A

dialysis: haemofiltration/haemodialysis

21
Q

What is the definition of hypokalaemia?

A

serum potassium <3.5 mmol/L

22
Q

What are 2 ways that causes of hypokalaemia can be split?

A
  1. renal and extra-renal
  2. with or without hypertension
23
Q

What is the difference between renal and extra-renal causes of hypokalaemia in terms of investigations?

A

urinary potassium; >20 mEq/L in renal causes, <20 mEq/L in extra-renal

24
Q

What are 5 renal causes of hypokalaemia?

A
  1. Diuretis (e.g. furosemide, thiazides)
  2. Renal tubular acidosis
  3. Bartter’s, Liddle’s and Gitelman’s syndromes
  4. Endocrine causes (hyperaldosteronism, Cushing’s)
  5. Hypomagnesaemia
25
Q

What are 3 extra-renal causes of hypokalaemia?

A
  1. Inadequate oral intake
  2. Gut losses (e.g. diarrhoea, vomiting, ileostomy, VIPoma, Zollinger-Ellison syndrome)
  3. Redistribution into cells (e.g. beta agonists, insulin, theophylline, alkalosis)
26
Q

What are 4 causes of hypokalaemia with hypertension?

A
  1. Cushing’s sndrome
  2. Conn’s syndrome (primary hyperaldosteronism)
  3. Liddle’s syndrome
  4. 11-beta hydroxylase deficiency (accounts for 90% of congenital adrenal hyperplasia cases but this is NOT assoc/w HTN)
27
Q

What is a drug which can potentially cause hypokalaemia associated with hypertension?

A

Carbenoxolone (anti-ulcer drug)

also liquorice excess

28
Q

What are 5 causes of hypokalaemia without hypertension?

A
  1. Diuretics
  2. GI loss (e.g. diarrhoea, vomiting)
  3. Renal tubular acidosis (type 1 and 2)
  4. Bartter’s syndrome
  5. Gitelman syndrome
29
Q

What are 2 clinical features of hypokalaemia?

A
  1. Muscle weakness
  2. Hypotonia
30
Q

Which drug must you be careful with in hypokalaemia?

A

digoxin toxicity - hypokalaemia prediposes to digoin toxicity

also take care if on diuretics

31
Q

What are 5 ECG features of hypokalaemia?

A
  1. U waves
  2. small or absent T waves
  3. prolonged PR interval
  4. ST depression
  5. long QT

(U have no P and no T but long PR and long QT)

32
Q

What are 4 causes of hypokalaemia with alkalosis?

A
  1. Vomiting
  2. Thiazide and loop diuretics
  3. Cushing’s syndrome
  4. Conn’s syndrome (primary hyperaldosteronism)
33
Q

What are 4 causes of hypokalaemia with acidosis?

A
  1. Diarhoea
  2. Renal tubular acidosis
  3. Acetazolamide
  4. Partially treated DKA
34
Q

What should be the approach when treating hypokalaemia caused by magnesium deficiency?

A

may need to correct magnesium deficiency before potassium level can be normalised

35
Q

What are 6 investigations to perform in hypokalaemia?

A
  1. ECG
  2. U+Es
  3. chloride
  4. bicarbonate
  5. glucose
  6. Urinary potassium and chloride
36
Q

What is the treatment of mild hypokalaemia?

A

oral slow release potassium chloride (Sando K)

treat causes, check potassium regularly

37
Q

What is the management of severe hypokalaemia? 5 aspects

A
  1. Continuous cardiac monitoring
  2. Check and correct magnesium (low Mg causes renal K+ wasting)
  3. IV infusion of 1L 0.9% saline containing 40 mmol KCl
  4. Avoid glucose and bicarbonate solutions
  5. Treat cause(s)
38
Q

What is the maximum rate of potassium replacement in hypokalaemia?

A

10 mmol/L hour

39
Q

What will need to be done to treat hypokalaemia if a faster rate of potassium replacement is required than 10 mmol per hour?

A

central line will need to be inserted - ITU/ call seniors etc.

AIP: Acute confusional state (14 decks)

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