Hyponatraemia

Question 1

Define hyponatraemia

Answer 1

Serum sodium <135

Question 2

Define severe hyponatraemia

Answer 2

Serum sodium <125

Question 3

Pathophysiology of hyponatraemia

Answer 3

Results from a relative excess of body water to sodium. Urinary dilutation is regulated by ADH

Question 4

What is the most common cause of hyponatraemia?

Answer 4

Impaired water excretion

Question 5

Causes of hyponatraemia: decreased extracellular volume

Answer 5

GI losses - severe D+V

Transdermal loss - sweating + extensive burns

Question 6

Causes of hyponatraemia: decreased extracellular volume

Answer 6

GI losses - severe D+V
Transdermal loss - sweating + extensive burns
Kidney disease
Third space losses - bowel obstruction, pancreatitis, sepsis, muscle trauma

Question 7

Causes of hyponatraemia: normal extracellular volume

Answer 7

SIAD
Excess H2O intake (e.g. excess IV fluids/ oral fluids)
MDMA

Question 8

Causes of hyponatraemia: increased extracellular volume

Answer 8

Heart failure
Liver failure
Kidney disease - CKD, nephrotic syndrome

Question 9

Drugs causing hyponatraemia

Answer 9

Diuretics (particularly thiazides)
SSRIs
NSAIDs
Carbamazepine

Question 10

Presentation of hyponatraemia

Answer 10

Headache, N+V, lethargy, cramps, dizziness, confusion

Question 11

What can happen in severe hyponatraemia?

Answer 11

Seixures, coma, cerebral oedema

Question 12

Would you see ECG chances in hyponatraemia?

Answer 12

NO!!

Question 13

How will most people with hyponatraemia present?

Answer 13

Asymptomatic

Question 14

What can chronic hyponatraemia lead to (presentation)?

Answer 14

Gait instability, falls, concentration + cognitive defects

Question 15

Management in moderate-severe hyponatraemia

Answer 15

Slowly give normal saline, but if hypervolaemic then fluid restrict