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Yr3 Medicine- Renal > Potassium Imbalances > Flashcards

Potassium Imbalances Flashcards

1
Q

What are the ranges for mild, moderate and severe hyperkalaemia?

A
  • Mild= 5.5.-5.9
  • Moderate= 6.0-6.4
  • Severe= >6.5
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2
Q

Why are we so concerned about hyperkalaemia?

A

Myocardial hyperexcitability can lead to ventricular fibrillation and cardiac arrest

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3
Q

State some potential causes of hyperkalaemia

A
  • Renal disease e.g. AKI, CKD
  • Medications (see separate card for medications)
  • Acidosis e.g. DKA
  • Addison disease
  • Excess administration
  • Tumour lysis syndrome
  • Rhabdomyolysis
  • Burns
  • Haemolysis (lab may state there is evidence of haemolysis if this is case)
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4
Q

State what medications can cause hyperkalaemia

A
  • ACE inhibitors
  • ARBs
  • Aldosterone receptor antagonists
  • NSAIDs
  • Ciclosporins
  • High dose trimethoprim
  • Digoxin toxicity
  • Beta-blockers
  • Heparin & LMWH
  • Some antifungals
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5
Q

What foods are rich in K+?

A
  • Dried fruit
  • Potatoes
  • Oranges
  • Tomatoes
  • Avocados
  • Nuts
  • Bananas
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6
Q

State the symptoms of hyperkalaemia

A

Pts may present non-specifically or with:

  • Muscle weakness
  • Palpitations
  • Light headedness
  • Chest pain
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7
Q

What might you find on clinical examination of someone with hyperkalaemia?

A
  • Tachycardia
  • Irregular pulse
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8
Q

What investigations would you do for someone who has hyperkalaemia, include:

  • Bedside
  • Bloods
  • Imaging

*Where possible, justify why you are doing each

A

Bedside

  • ECG: check for arrhythmias
  • Ketones & BMs: DKA can cause hyperkalaemia
  • Synacthen: check for Addisons

Bloods

  • U&Es: check if cause is renal
  • Creatine kinase: check if cause is rhabdomyolysis

Imaging

  • No specific
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9
Q

What ECG features would you see in hyperkalaemia?

A
  • Flattened/small P waves
  • Broadening of the QRS
  • Tall tented T waves

May progress to sinusoidal wave pattern and ventricular fibrillation

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10
Q

Discuss the management of hyperkalaemia of <6mmol/L (a.ka. mild hyperkalaemia) with stable renal function

A

Don’t need urgent treatment. Management involves:

  • Stopping medications that increase K+/adjusting medications
  • Cardiac monitoring
  • Consider calcium resonium
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11
Q

Discuss the management of hyperkalaemia:

  • >6mmol/L and ECG changes
  • >6.5mmol/L
A

>6mmol/L and ECG changes= urgent treatment

>6.5mmol/L= urgent treatment regardless of ECG changes

Urgent treatment

  1. Calcium gluconate
  2. Shift K+ into cells:
    1. Insulin/dextrose infusion
    2. Salbutamol nebs
  3. Eliminate potassium from body:
    1. Calcium resonium
    2. Furosemide
    3. Hemofiltration/dialysis
  4. Hemofiltration/dialysis
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12
Q

What doses of the following medications do you give for hyperkalaemia:

  • Calcium gluconate
  • Insulin/dextrose infusion
  • Salbutamol nebs
  • Calcium resonium
  • Furosemide
A
  • Calcium gluconate: 30mL of 10% calcium gluconate over 5-10 mins
  • Insulin/dextrose infusion: 10 units of actrapid and IV glucose/dextrose 50% 50mL
  • Salbutamol nebs: 5-10mg via nebuliser
  • Calcium resonium: 15-45g orally or rectally (mixed with sorbitol or lactulose- both laxatives)
  • Furosemide: 20-80mg depending on hydration status. Calcium gluconate is first line
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13
Q

Explain how each of the following drugs works in hyperkalaemia:

  • Calcium gluconate
  • Insulin
  • Salbutamol
  • Calcium resonium
A
  • Calcium gluconate: stabilises cardiac membrane reducing risk of arrhythmias
  • Insulin: causes K+ to move intracellularly
  • Salbutamol: causes K+ to move intracellularly
  • Calcium resonium: draws K+ out of gut and into stools to increase potassium excretion
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14
Q

State some potential complications of hyperkalaemia

A
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15
Q

What is psuedohyperkalaemia?

A

False elevation in serum potassium- also known as artefact hyperkalaemia; potential causes include:

  • Obtaining blood samples form a limb receiving IV potassium
  • Haemolysis in difficult venepuncture
  • Leucocytosis
  • Thrombocytosis
  • Delayed analysis (RBCs leak K+)
  • Contamination with K+ EDTA anticoagulation in FBC bottles
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16
Q

What is hypokalaemia (asking for serum level)?

A

Serum K+ < 3.5mmol/L

17
Q

State some potential causes for hypokalaemia

A
  • Reduced oral intake
  • GI losses e.g. vomiting & diarrhoea
  • Medications e.g. diuretics, insulin
  • Endocrine: Conn’s or Cushing’s syndrome
  • Renal losses e.g. in herediatary tubulopathies e.g. Bartter & Gitelman syndrome

*NOTE: hypokalaemia alongside hypophsophataemia is seen in refeeding syndrome

18
Q

State the symptoms of hypokalaemia

A
  • Fatigue
  • Constipation
  • Proximal muscle weakness
  • Hypotonia
  • Hyporeflexia
  • Cramps
  • Tetany
  • Palpitations
  • Light headedness (arrhythmias)
  • Worsened glucose control in diabetics
19
Q

State what you might find on clinical examination of someone with hypokalaemia

A
  • Hypotonia
  • Hyporeflexia
  • Irregular HR
  • Hypertension
20
Q

Discuss the effect of serum magnesium levels on serum potassium levels

A

Low magnesium can impair kidneys ability to retain potassium and hence can lead to hypokalaemia

21
Q

State what investigations you would do for hypokalaemia, include:

  • Bedside
  • Bloods
  • Imaging

*For each, justify why you are doing it. NOTE: you could do lots as there as so many causes of hypokalaemia. Focus on main ones

A

Bedside

  • ECG: check for arrhythmias
  • BMs: in diabetics as hypokalaemia can worsen glucose control

Bloods

  • U&Es: check renal function
  • Magnesium: hypomagnesaemia can impair K+ retention by kidneys

Imaging

  • No specific
22
Q

What might you see on the ECG of someone with hypokalaemia?

A
  • Flattened T waves
  • U waves
  • Increased PR interval
  • ST depression
  • Long QT
23
Q

Discuss the management of hypokalaemia, consider management if:

  • K+ 2.5-3.5mmol/L
  • K+ < 2.5mmol/L
A

K+ 2.5-3.5mmol/L

  • Oral K+ supplements e.g. Sando-K tablets

K+ >2.5mmol/L

  • IV KCl usually given in 0.9% NaCl (do NOT exceed more than 20mmol/hr and not more concentrated than 40mmol/L)
  • *NOTE: don’t give IV KCL in dextrose as this further induced hypokalaemia*
24
Q

State some potential complications of hypkalaemia

A
  • Paralysis and respiratory failure
  • Cardiac arrhythmias

Yr3 Medicine- Renal (8 decks)

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