General - Sodium

Question 1

Hypernatraemia is when sodium concentration is greater than what?

Answer 1

> 145mmol/L

Question 2

1) Name a symptom of hypernatremia
2) Name a sign of hypernatremia

Answer 2

1) Lethargy, weakness, excessive thirst
2) Confusion, agitation, seizures, coma

Question 3

Name 4 causes of hypernatremia

Answer 3

• Excess water loss (diabetes insipidus, diuretics, osmotic diuresis i.e. DKA and HHS, diarrhoea, vomiting and NG suction, sweating, burns
• Excessive hypertonic fluid (IV infusions, total parenteral nutrition, enteral feeds)
• Decreased thirst (acute illness, old age)

Question 4

Hyponatraemia is a serum sodium concentration of less than what?

Answer 4

<135mmol/L

Question 5

1) Name an early symptom of hyponatremia
2) Name a late symptom of hyponatremia

Answer 5

1) Headache, lethargy, nausea, vomiting, dizziness, muscle cramps and confusion
2) Seizures coma and respiratory arrest

Question 6

1) Name a cause of hypovolaemia hyponatremia
2) Name a cause of euvolemic hyponatremia
3) Name a cause of hypervolaemia hyponatremia

Answer 6

1) Burns, sweating, diarrhoea, vomiting, fistulae, Addison’s disease
2) Syndrome of inappropriate ADH release (SIADH), hypothyroidism
3) Renal failure, heart failure, liver failure, nephrotic syndrome

Question 7

1) How is hypovolaemia hyponatremia managed?
2) How is euvolemic hyponatremia due to SIADH managed?
3) How is euvolemic hyponatremia due to hypothyroidism?
4) How is hypervolaemia hyponatremia managed?

Answer 7

1) IV normal saline and treatment of the underlying cause
2) Fluid restriction, ADH receptor antagonist i.e. tolvaptan, oral sodium and furosemide
3) Levothyroxine
4) Fluid restriction and treatment of underlying cause

Question 8

Correcting sodium faster than 12mmol/L/day leads to a significant risk of what?

Answer 8

Central pontine myelinolysis

Question 9

What happens in central pontine myelinolysis

Answer 9

The rapid rise in sodium concentration is accompanied by the movement of small molecules and pulls water from brain cells. This leads to the destruction of myelin