Potassium

Question 1

What is the normal concentration of potassium in the blood?

Answer 1

3.5-5mmol/l

Question 2

What percentage of potassium is extracellular?

Answer 2

2%

Question 3

State at least 5 causes of hypokalaemia

Answer 3

GI loss, hyperaldosteronism, thiazide diuretics, loop diuretics, osmotic diuresis, high insulin, metabolic alkalosis, hypomagnesaemia, renal tubular acidosis types 1 and 2

Question 4

Describe type 1 renal tubular acidosis

Answer 4

Distal failure of hydrogen ion excretion with subsequent acidosis and hypokalaemia. Most severe renal tubular acidosis

Question 5

Describe type 2 renal tubular acidosis

Answer 5

Proximal failure to reabsorb bicarbonate with subsequent acidosis and hypokalaemia

Question 6

Describe type 4 renal tubular acidosis

Answer 6

Aldosterone deficiency or resistance leading to acidosis and hyperkalaemia

Question 7

What is the treatment for hypokalaemia?

Answer 7

Oral SandoK and potassium monitoring

Below 3.0mmol/l consider IV potassium chloride at no more than 10mM/hr to avoid arrhythmia

Question 8

What are the three overarching causes of hyperkalaemia?

Answer 8

Excessive intake, transcellular movement, decreased excretion

Question 9

State 3 causes of excessive potassium intake

Answer 9

Dietary, unbalanced parenteral nutrition, stored blood transfusion

Question 10

State 3 causes of hyperkalaemia by transcellular movement

Answer 10

Acidosis, diabetic ketoacidosis, rhabdomyolysis

Question 11

State 5 causes of decreased potassium excretion

Answer 11

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)

Question 12

State the essential investigations for hyperkalaemia

Answer 12

Repeat blood test (apparent hyperkalaemia can be caused by a haemolysed blood sample), ECG

Question 13

Describe the ECG changes associated with hyperkalaemia

Answer 13

Loss of P waves, tall tented T waves, widened QRS, eventually sine wave formation

Question 14

What is the treatment for hyperkalaemia?

Answer 14

10mls 10% calcium gluconate, 100mls 20% dextrose or 50mls 50% dextrose, 10 units insulin
Adjunct: salbutamol
Treat cause

Question 15

What is the role of calcium gluconate in hyperkalaemia

Answer 15

Cardioprotective

Question 16

In which group of patients is IV calcium gluconate dangerous?

Answer 16

Those on digoxin - can precipitate arrhythmias, patients should be on cardiac monitoring

Question 17

Describe the sodium and potassium results in Conn’s syndrome

Answer 17

High or upper normal sodium, low or lower normal potassium

Question 18

Describe the sodium and potassium results in Addison’s disease

Answer 18

Low or lower normal sodium, high or upper normal potassium

Question 19

For every drop in pH of 0.1, how much does potassium increase by?

Answer 19

0.7mmol/l