Potassium Flashcards
What is the normal concentration of potassium in the blood?
3.5-5mmol/l
What percentage of potassium is extracellular?
2%
State at least 5 causes of hypokalaemia
GI loss, hyperaldosteronism, thiazide diuretics, loop diuretics, osmotic diuresis, high insulin, metabolic alkalosis, hypomagnesaemia, renal tubular acidosis types 1 and 2
Describe type 1 renal tubular acidosis
Distal failure of hydrogen ion excretion with subsequent acidosis and hypokalaemia. Most severe renal tubular acidosis
Describe type 2 renal tubular acidosis
Proximal failure to reabsorb bicarbonate with subsequent acidosis and hypokalaemia
Describe type 4 renal tubular acidosis
Aldosterone deficiency or resistance leading to acidosis and hyperkalaemia
What is the treatment for hypokalaemia?
Oral SandoK and potassium monitoring
Below 3.0mmol/l consider IV potassium chloride at no more than 10mM/hr to avoid arrhythmia
What are the three overarching causes of hyperkalaemia?
Excessive intake, transcellular movement, decreased excretion
State 3 causes of excessive potassium intake
Dietary, unbalanced parenteral nutrition, stored blood transfusion
State 3 causes of hyperkalaemia by transcellular movement
Acidosis, diabetic ketoacidosis, rhabdomyolysis
State 5 causes of decreased potassium excretion
Oliguric phase of acute renal failure, late chronic renal failure, potassium-sparing diuretics e.g. spironolactone, Addison’s disease, drugs (NSAIDs, ACE inhibitors, angiotensin-receptor blockers)
State the essential investigations for hyperkalaemia
Repeat blood test (apparent hyperkalaemia can be caused by a haemolysed blood sample), ECG
Describe the ECG changes associated with hyperkalaemia
Loss of P waves, tall tented T waves, widened QRS, eventually sine wave formation
What is the treatment for hyperkalaemia?
10mls 10% calcium gluconate, 100mls 20% dextrose or 50mls 50% dextrose, 10 units insulin
Adjunct: salbutamol
Treat cause
What is the role of calcium gluconate in hyperkalaemia
Cardioprotective
In which group of patients is IV calcium gluconate dangerous?
Those on digoxin - can precipitate arrhythmias, patients should be on cardiac monitoring
Describe the sodium and potassium results in Conn’s syndrome
High or upper normal sodium, low or lower normal potassium
Describe the sodium and potassium results in Addison’s disease
Low or lower normal sodium, high or upper normal potassium
For every drop in pH of 0.1, how much does potassium increase by?
0.7mmol/l
