Electrolyte Imbalances

Question 1

What are the signs and symptoms of hyponatraemia?

Answer 1

Anorexia
Nausea
Malaise

Headache
Irritability 
Confusion
Weakness
Reduced GCS and seizures 

• HF or oedema may indicate the cause for hyponatraemia
• *hyponatraemia also increases risk of falls in the elderly

Question 2

What are the causes of hyponatraemia?

Scenario: pt is dehydrated and urine Na+ conc is >20mmol/L

Answer 2

Sodium and water are both being lost via the kidneys:
Diuretics diuresis
Renal failure
Osmolar diuresis (high glucose/urea)
Addison’s disease

Question 3

What are the causes of hyponatraemia?

Scenario: pt is dehydrated and urine Na+ is under 20mmol/L

Answer 3

Sodium and water are being lost but not from the kidneys:
Diarrhoea
Vomiting 
Burns 
Trauma 
Small bowel obstruction 
CF
Heat exposure

Question 4

What are the causes of hyponatraemia?

Scenario: pt is not dehydrated, pt is oedematous.

Answer 4

Causes of fluid overload:
Nephrotic syndrome
Cardiac failure
Renal failure
Cirrhosis (liver failure)

Question 5

What are the causes of hyponatraemia?

Scenario: pt is not dehydrated, pt is no oedematous, pt’s urine osmolality is over 100mmol/Kg?

Answer 5

Urine is really concentrated and water is being retained:

SIADH

Question 6

What are the causes of hyponatraemia?

Scenario: pt is not dehydrated, pt is not oedematous, pts urine osmolality is not over 100mmol/Kg

Answer 6

Pt has enough fluid to dilute urine, but not so much that the pt is dehydrated:
Water overload
Severe hypothyroidism
Glucocorticoid insufficiency (lack of aldosterone)

Question 7

What are the signs and symptoms of hypernatraemia?

Answer 7

Lethargy, thirst, weakness, irritability, confusion, coma, fits
May have signs of dehydration

Question 8

What are the causes of hypernatraemia?

Answer 8

Usually due to water loss in excess of Na+ loss:

• fluid loss without replacement (diarrhoea, vomiting, burns)
• diabetes insipidus
• osmotic diuresis
• primary aldosteronism
• iatrogenic (incorrect fluid replacement- too much saline)

Question 9

What is the management for hypernatraemia?

Answer 9

Give water orally if possible
If not, give glucose 5% IV slowly (1L/hr)

Use 0.9% saline IV in hypovolaemia since this causes less marked fluid shifts