Hyper/hypokalaemia Flashcards
What are the main groups of causes of hyperkalaemia?
- Decreased excretion
- Increased release from cells
- Increased extranious load
- Spurious
What problems can caused decreased excretion of potassium?
- Decreased GFR - AKI/CKD
- Decreased mineral corticoid activity
- Defect in tubular secretion - renal tubular acidosis
- Drugs - NSAIDs, cyclosporine, potassium-sparing diuretics, ACE Inhibitors
What are causes of increased release from cells which cause hyperkalaemia?
- Acidosis (metabolic/diabetic or respiratory)
- Insulin deficiency
- Drugs - digoxin toxicity
- Rhabdomyolysis
- Tumour lysis syndrome
- Haemolysis
- Extensive burns
What are sources of exogenous potassium which can cause hyperkalaemia?
- Potassium supplements (IV or Oral)
- Excess in diet
- Salt substitutes (e.g. potassium salts of penicillin)
What are clinical features of hyperkalaemia?
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
What is the main worry with hyperkalaemia?
Cardiac hyperexcitability -> VF -> CArdiac arrest
What artefactual results could create spurious hypperkalaemia?
- Haemolysis
- COntamination with potassium EDTA antiocoagulant
- Thrombocytopenia
- Delayed analysis - K+ leaks out of RBCs
What investigations would you consider doing in someone who had hyperkalaemia?
- Bloods - U+E’s, ABG, Tests for other causes (e.g. short synacthen etc.)
- ECG
What ECG changes might you see in someone with hyperkalaemia?
In order of when it occurs
- Tall tented T waves
- Loss of P waves
- Widened QRS complex
- Sine wave
- Asystole
When would you consider emergency treatment for someone with hyperkalaemia?
K+ > 6.5 mmol/L or with any ECG changes
How would you immediately manage someone with a K+ > 6.5 mmol/L or who had ECG changes?
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
What volume and dose of calcium gluconate would you use to treat hyperkalaemia?
30 ml of 10% calcium gluconate
Over what time perioud would you give calcium gluconate?
5-10 minutes
How many units of insulin would you give someone when treating hyperkalaemia?
10 units
What would you need to monitor for in someone who you are giving insulin to?
Hypoglycaemia - hourly BGs
What dose of nebulised salbutamol would you consider giving someone when treating hyperkalaemia?
10-20mg - watch for tachycardia
What drugs can cause hyperkalaemia?
- Amiloride
- Spironolactone
- ACEi
- NSAIDS
- Digoxin toxicity
- Ciclosporin
How would you consider managing someone with non-urgent hyperkalaemia?
- Treat unerlying cause
- Review medications
- Consider Calcium resonium - oral or enema
How does calcium resonium work?
Binds K+ in the gut, preventing absorption and bringing K+ levels down over a few days
What are groups of causes of hypokalaemia?
- Increased excretion
- Increased aldosterone
- Exogenous
- Renal disease
- Reduced K+ intake
- REdistribution into cells
- GI losses
What are causes of increased aldosterone which causes hypokalaemia?
- Liver failure
- Heart failure
- Nephrotic syndrome
- Cushing’s syndrome
- Conn’s Syndrome
- ACTH producing tumours
What can increase renal secretion of potassium?
Diuretics - Thiazide, Loop
What renal tubular diseases can cause hypokalaemia?
- Renal tubular acidosis
- Renal tubular damage
- Acute leukaemia
- Nephrotoxicity
- Release of urinary obstruction - pathological diuresis
What are causes of hypokalaemia which are due to redistribution into cells?
- B-adrenergic stimulation
- MI
- B-agonist
- Insulin Treatment
- Alkalosis
- Correction of megaloblastic anaemia
What are causes of hypokalaemia which are due to GI losses?
- Vomiting
- Severe diarrhoea
- Purgative abuse
- Ileostomy
- Fistulae
- Ileus/intestinal obstruction
What are clinical features of hypokalaemia?
- Muscle weakness
- Hypotonia
- Hyporeflexia
- Cramps
- Tetany
- Palpitations
- Light headedness
- Constipation
What investigations would you do in someone with suspected Hypokalaemia?
- Bloods - U+E’s, Creatinine,
- ECG
What are Drugs which can cause hypokalaemia?
- 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)
What ECG changes might you see in someone with hypokalaemia?
- Small/inverted T waves
- Prominent U waves
- Long PR interval
- Depressed ST segments
What would you suspect as the cause of hyperkalaemia if an individual had hypertensive, hypokalaemic acidosis?
Conn’s syndrome
How would you manage mild hypokalaemia?
>2.5 mmol/L, no symptoms
- Oral K+ - Sando K
How woul dyou manage severe hypokalaemia?
<2.5 mmol +/- dangerous symptoms
- IV potassium cautiously - never as fast stat bolus
- ECG monitoring
What is the maximum rate you would consider giving IV potassium at?
20 mmol/hr
What is the importance of using a dextrose free solution when giving someone IV potassium to treat hypokalaemia?
PRevents excess insulin secretion -> causes potassium movement into cells thus worsening hypokalaemia
