Hyper/hypokalaemia Flashcards

1
Q

What are the main groups of causes of hyperkalaemia?

A
  • Decreased excretion
  • Increased release from cells
  • Increased extranious load
  • Spurious
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2
Q

What problems can caused decreased excretion of potassium?

A
  • Decreased GFR - AKI/CKD
  • Decreased mineral corticoid activity
  • Defect in tubular secretion - renal tubular acidosis
  • Drugs - NSAIDs, cyclosporine, potassium-sparing diuretics, ACE Inhibitors
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3
Q

What are causes of increased release from cells which cause hyperkalaemia?

A
  • Acidosis (metabolic/diabetic or respiratory)
  • Insulin deficiency
  • Drugs - digoxin toxicity
  • Rhabdomyolysis
  • Tumour lysis syndrome
  • Haemolysis
  • Extensive burns
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4
Q

What are sources of exogenous potassium which can cause hyperkalaemia?

A
  • Potassium supplements (IV or Oral)
  • Excess in diet
  • Salt substitutes (e.g. potassium salts of penicillin)
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5
Q

What are clinical features of hyperkalaemia?

A

Can be asymptomatic, or:

  • Muscle weakness
  • Tremor
  • Kussmauls respiration - if associated with metabolic acidosis
  • Hypotension
  • Tachy/Bradycardia with irregular rhythm
  • Chest pain
  • Palpitations
  • Light-headedness
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6
Q

What is the main worry with hyperkalaemia?

A

Cardiac hyperexcitability -> VF -> CArdiac arrest

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7
Q

What artefactual results could create spurious hypperkalaemia?

A
  • Haemolysis
  • COntamination with potassium EDTA antiocoagulant
  • Thrombocytopenia
  • Delayed analysis - K+ leaks out of RBCs
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8
Q

What investigations would you consider doing in someone who had hyperkalaemia?

A
  • Bloods - U+E’s, ABG, Tests for other causes (e.g. short synacthen etc.)
  • ECG
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9
Q

What ECG changes might you see in someone with hyperkalaemia?

A

In order of when it occurs

  1. Tall tented T waves
  2. Loss of P waves
  3. Widened QRS complex
  4. Sine wave
  5. Asystole
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10
Q

When would you consider emergency treatment for someone with hyperkalaemia?

A

K+ > 6.5 mmol/L or with any ECG changes

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11
Q

How would you immediately manage someone with a K+ > 6.5 mmol/L or who had ECG changes?

A

Buy time

  • 10ml 10% calcium chloride/30ml 10% calcium gluconate - 5-10 minutes
  • IV insulin (10 units) + 25g glucose (50 ml of 50%/125ml of 20%)
  • Nebulised Salbutamol 10-20 mg

Difinitive removal

  • Correct underlying pathology
  • Haemodialysis
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12
Q

What volume and dose of calcium gluconate would you use to treat hyperkalaemia?

A

30 ml of 10% calcium gluconate

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13
Q

Over what time perioud would you give calcium gluconate?

A

5-10 minutes

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14
Q

How many units of insulin would you give someone when treating hyperkalaemia?

A

10 units

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15
Q

What would you need to monitor for in someone who you are giving insulin to?

A

Hypoglycaemia - hourly BGs

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16
Q

What dose of nebulised salbutamol would you consider giving someone when treating hyperkalaemia?

A

10-20mg - watch for tachycardia

17
Q

What drugs can cause hyperkalaemia?

A
  • Amiloride
  • Spironolactone
  • ACEi
  • NSAIDS
  • Digoxin toxicity
  • Ciclosporin
18
Q

How would you consider managing someone with non-urgent hyperkalaemia?

A
  • Treat unerlying cause
  • Review medications
  • Consider Calcium resonium - oral or enema
19
Q

How does calcium resonium work?

A

Binds K+ in the gut, preventing absorption and bringing K+ levels down over a few days

20
Q

What are groups of causes of hypokalaemia?

A
  • Increased excretion
  • Increased aldosterone
  • Exogenous
  • Renal disease
  • Reduced K+ intake
  • REdistribution into cells
  • GI losses
21
Q

What are causes of increased aldosterone which causes hypokalaemia?

A
  • Liver failure
  • Heart failure
  • Nephrotic syndrome
  • Cushing’s syndrome
  • Conn’s Syndrome
  • ACTH producing tumours
22
Q

What can increase renal secretion of potassium?

A

Diuretics - Thiazide, Loop

23
Q

What renal tubular diseases can cause hypokalaemia?

A
  • Renal tubular acidosis
  • Renal tubular damage
  • Acute leukaemia
  • Nephrotoxicity
  • Release of urinary obstruction - pathological diuresis
24
Q

What are causes of hypokalaemia which are due to redistribution into cells?

A
  • B-adrenergic stimulation
  • MI
  • B-agonist
  • Insulin Treatment
  • Alkalosis
  • Correction of megaloblastic anaemia
25
Q

What are causes of hypokalaemia which are due to GI losses?

A
  • Vomiting
  • Severe diarrhoea
  • Purgative abuse
  • Ileostomy
  • Fistulae
  • Ileus/intestinal obstruction
26
Q

What are clinical features of hypokalaemia?

A
  • Muscle weakness
  • Hypotonia
  • Hyporeflexia
  • Cramps
  • Tetany
  • Palpitations
  • Light headedness
  • Constipation
27
Q

What investigations would you do in someone with suspected Hypokalaemia?

A
  • Bloods - U+E’s, Creatinine,
  • ECG
28
Q

What are Drugs which can cause hypokalaemia?

A
  • Diuretics (Loop and Thiazides)
  • Mannitol
  • Penicillin
  • Amphotericin
  • Steroids (Renal loss)
  • Gentamicin
  • Cisplatin
  • Amphotericin (Associated with hypomagnesemia)
  • Insulin
  • Beta agonists
  • Adrenaline
  • Salbutamol
  • Lithium (Na/K ATPase increase)
29
Q

What ECG changes might you see in someone with hypokalaemia?

A
  • Small/inverted T waves
  • Prominent U waves
  • Long PR interval
  • Depressed ST segments
30
Q

What would you suspect as the cause of hyperkalaemia if an individual had hypertensive, hypokalaemic acidosis?

A

Conn’s syndrome

31
Q

How would you manage mild hypokalaemia?

A

>2.5 mmol/L, no symptoms

  • Oral K+ - Sando K
32
Q

How woul dyou manage severe hypokalaemia?

A

<2.5 mmol +/- dangerous symptoms

  • IV potassium cautiously - never as fast stat bolus
  • ECG monitoring
33
Q

What is the maximum rate you would consider giving IV potassium at?

A

20 mmol/hr

34
Q

What is the importance of using a dextrose free solution when giving someone IV potassium to treat hypokalaemia?

A

PRevents excess insulin secretion -> causes potassium movement into cells thus worsening hypokalaemia