13. Potassium disorders Flashcards
Where is potassium mainly contained?
Within cells
What are the classic features of changes in potassium?
Changes in the ECG
How does potassium change in hyperkalaemia
Tall tented T wave
Small P wave
Broad QRS
What are the different reasons for a high potassium
Kidney function is reduced
Redistribution
Increased intake
What kidney problems cause hyerkaelemia?
Renal failure
ACE inhibitors- (reduced aldosterone, reduced K excretion)
Potassium sparing diuretics (sporonolactone)
Addison’s disease
What is good to keep in mind for low serum sodium, high serum potassium
Addisons disease
Explain redistribution hyperkalaemia
Metabolic Acidosis causes potassium to move out of the cell to maintain electroneutrality within the cell
Discuss hyperkaelemia due to increased intake
Unlikely unless there is also impaired renal excretion
Over supplementation of IV fluids or TPN
Blood transfusion- potassium rich cells
What is pseudohyperkalaemia?
High potassium on blood results although potassium is not actually that high within the body.
What are the causes of pseudohyperkalaemia
Caused due to haemolysis when blood is being taken
Delayed centrifugation (RBC leaks out of cells)
Sample contamination
Increased platelet or white cell count
Someones bloods show high potassium- what is teh first step
Look at drugs, heamolysis, renal failure, addisons,
What are the less common causes?
Tumour lysis syndorme
Rhabdomyolsis
Metabolic acidossis
What are the extremely extremely rare causes?
If youve got here get a second opinion. Paralysis diseases, pseduohyperkaelemia
What can be given to correct potassium imbalance
Insulin (also give with glucose)
Salbutamol (nebulised)
Dialysis
How do you tell between kidney injury and dehydrtion?
Urea and creatinine should be proportionately high (e.g. both doubled)
What are the ECG chanegs on hypokalaemia?
Flattened T wave
U wave
Smaller QRS
Prolonged QT
What causes hypokalaemia?
GI loss (Intestinal fistula, overuse of laxatives, V&D) Increased renal excretion
What causes hypokalaemia?
GI loss (Intestinal fistula, overuse of laxatives, V&D)
Increased renal excretion
redistriution
What renal causes are there of hypokalaemia?
Diuretics
Magnesium syndrome- low potassium, low calcium
cushings syndrome- (excess cortisol causes)
Conn’s syndrome- (excess aldosterone causes)
Bartter’s or Gitelmans (rare)
Renal tubuar acidosis (rare)
How does redistribution cause hypokaelmia
Insulin (high dose) B2 agonsits (salbutamol) Metabolic alkalosis
What are the most common causes of hypokalaemia?
Vomiting, diorrea? Surgery (fistula) Drugs? Metabolic alkalosis Excess urinary loss? (renal vs gut loss) Loop or thiazide diuretics
At what rate should you give potassium?
Do not give IV potassium faster than 20mmol/hour
Monitor with ECg if giving faster than 10mmol
NEVER EVER EVER GIVE BOLUS POTASSIUM
