Electrolyte Imblances

Question 1

What are the normal Potassium levels

Answer 1

2.5 to 6.5 mmol/L

Question 2

What issue does Hyperkalemia pose?

Answer 2

There can be myocardial hyperexcitability leading to ventricular fibrillation and cardiac arrest

Question 3

How does hyperkalemia present?

Answer 3

Fast irregular pulse, chest pain, weakness, palpitations and light headedness

Question 4

What are the ECG findings for hyperkalemia?

Answer 4

Tall tented T waves, increased PR interval, small or absent P waves, wide QRS complex - eventually becoming sinusoidal, ventricular fibrillation, sine wave pattern, asystole.

Question 5

When should artefactual results be suspected and what should be done when they’re suspected?

Answer 5

If patient is well, has no signs and symptoms, repeat the test urgently as it may be artefactual.

Question 6

What are the causes of artefactual hyperkalemia results?

Answer 6

• Hemolysis - Difficult venepuncture; patient clenched fist
• Contamination with potassium EDTA anticoagulant in FBC bottles (FBC should be done after U&E)
• Thrombocythaemia (K+ leaks out of platelets during clotting)
• Delayed analysis (K+ leaks out of RBCs; long transit time to lab)

Question 7

What are the causes of hyperkalemia?

Answer 7

• Oliguric renal failure
• Potassium sparing diuretics
• Rhabdomyolysis
• Metabolic acidosis
• Excess K+ therapy
• Addison’s disease
• Massive blood transfusion
• Burins
• Drugs eg. ACE-I, suxamethonium
• Artefactual result

Question 8

How is Hyperkalemia treated - non-urgent cases?

Answer 8

• Treat the underlying cause; review medications.
• Polystyrene sulfonate resin - Calcium Resonium 15g/8h PO. It binds K+ in the gut preventing absorption and bringing K+ levels down over a few days. If vomiting prevents PO admin, give a 30g enema, followed at 9h by colonic irrigation.

Question 9

When is Emergency treatment given for hyperkalemia?

Answer 9

If there’s evidence of myocardium hyperexcitability, or K+ is more than 6.5mmol/L. Get senior assistance as well.

Question 10

What are the lab values for hypokalemia and hyperkalemia?

Answer 10

Hypokalemia <2.5mmol/L
Hyperkalemia - >6.5mmol/L

Question 11

How does hypokalemia affect digoxin?

Answer 11

It exacerbates digoxin toxicity

Question 12

What are the signs and symptoms of hypokalemia?

Answer 12

Muscle weakness, Hypotonia, Hyporeflexia, Cramps, Tetany, Palpitations, Light-headedness (arrhythmias), Constipation

Question 13

What are ECG findings in hypokalemia?

Answer 13

Small or inverted T waves, Prominent U waves ( after T wave), long PR interval and depressed ST segments.

Question 14

What are the causes of hypokalemia?

Answer 14

• Diuretics
• Vomiting and Diarrhoea
• Pyloric stenosis
• Rectal villous adenoma
• Intestinal fistula
• Cushing’s syndrome/steroids/ACTH
• Conn’s syndrome
• Alkalosis
• Purgative and liquorice abuse
• Renal tubular failure

Question 15

When do you suspect Conn’s syndrome in a patient with hypokalemia?

Answer 15

If patient is hypertensive, hypokalemic alkalosis in someone not taking diuretics.

Question 16

What is the best indication that hypokalemia is likely to have been longstanding in a patient is on diuretics?

Answer 16

High HCO3-

Question 17

What other electrolyte is affected when there’s hypokalemia? How does this affect the management of hypokalemia?

Answer 17

Mg2+. Hypokalemia is difficult to correct until Mg2+ levels are normalized.

Question 18

What occurs in hypokalemic periodic paralysis?

Answer 18

There’s intermittent weakness lasting up to 72 hours, apparently caused by K+ shifting from extra- to intracellular fluid.

Question 19

How is Hypokalemia treated?