Potassium Imbalances Flashcards
What are the ranges for mild, moderate and severe hyperkalaemia?
- Mild= 5.5.-5.9
- Moderate= 6.0-6.4
- Severe= >6.5
Why are we so concerned about hyperkalaemia?
Myocardial hyperexcitability can lead to ventricular fibrillation and cardiac arrest
State some potential causes of hyperkalaemia
- 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)
State what medications can cause hyperkalaemia
- ACE inhibitors
- ARBs
- Aldosterone receptor antagonists
- NSAIDs
- Ciclosporins
- High dose trimethoprim
- Digoxin toxicity
- Beta-blockers
- Heparin & LMWH
- Some antifungals
What foods are rich in K+?
- Dried fruit
- Potatoes
- Oranges
- Tomatoes
- Avocados
- Nuts
- Bananas
State the symptoms of hyperkalaemia
Pts may present non-specifically or with:
- Muscle weakness
- Palpitations
- Light headedness
- Chest pain
What might you find on clinical examination of someone with hyperkalaemia?
- Tachycardia
- Irregular pulse
What investigations would you do for someone who has hyperkalaemia, include:
- Bedside
- Bloods
- Imaging
*Where possible, justify why you are doing each
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
What ECG features would you see in hyperkalaemia?
- Flattened/small P waves
- Broadening of the QRS
- Tall tented T waves
May progress to sinusoidal wave pattern and ventricular fibrillation
Discuss the management of hyperkalaemia of <6mmol/L (a.ka. mild hyperkalaemia) with stable renal function
Don’t need urgent treatment. Management involves:
- Stopping medications that increase K+/adjusting medications
- Cardiac monitoring
- Consider calcium resonium
Discuss the management of hyperkalaemia:
- >6mmol/L and ECG changes
- >6.5mmol/L
>6mmol/L and ECG changes= urgent treatment
>6.5mmol/L= urgent treatment regardless of ECG changes
Urgent treatment
- Calcium gluconate
- Shift K+ into cells:
- Insulin/dextrose infusion
- Salbutamol nebs
- Eliminate potassium from body:
- Calcium resonium
- Furosemide
- Hemofiltration/dialysis
- Hemofiltration/dialysis
What doses of the following medications do you give for hyperkalaemia:
- Calcium gluconate
- Insulin/dextrose infusion
- Salbutamol nebs
- Calcium resonium
- Furosemide
- 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
Explain how each of the following drugs works in hyperkalaemia:
- Calcium gluconate
- Insulin
- Salbutamol
- Calcium resonium
- 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
State some potential complications of hyperkalaemia
What is psuedohyperkalaemia?
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
What is hypokalaemia (asking for serum level)?
Serum K+ < 3.5mmol/L
State some potential causes for hypokalaemia
- 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
State the symptoms of hypokalaemia
- Fatigue
- Constipation
- Proximal muscle weakness
- Hypotonia
- Hyporeflexia
- Cramps
- Tetany
- Palpitations
- Light headedness (arrhythmias)
- Worsened glucose control in diabetics
State what you might find on clinical examination of someone with hypokalaemia
- Hypotonia
- Hyporeflexia
- Irregular HR
- Hypertension
Discuss the effect of serum magnesium levels on serum potassium levels
Low magnesium can impair kidneys ability to retain potassium and hence can lead to hypokalaemia
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
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
What might you see on the ECG of someone with hypokalaemia?
- Flattened T waves
- U waves
- Increased PR interval
- ST depression
- Long QT
Discuss the management of hypokalaemia, consider management if:
- K+ 2.5-3.5mmol/L
- K+ < 2.5mmol/L
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*
State some potential complications of hypkalaemia
- Paralysis and respiratory failure
- Cardiac arrhythmias
