4. Hypo And Hypernatraemia

Question 1

What are the causes of hypernatraemia?

Answer 1

Osmotic diuresis
Fluid loss without replacement
Diabetes insipidus
Incorrect IV fluid replacement
Primary aldosteronism

Question 2

What is hyponatraemia usually due to?

Answer 2

An increase in water/error in water balance

Question 3

What are the symptoms of hyponatraemia?

Answer 3

Correlates to severity and rate of onset

Neurological: agitation, nausea, focal neurology, coma

Question 4

What are the causes of hyponatraemia?

Answer 4

Diuretics
Water overload or retention
Increased ADH secretion
Increased plasma osmolality
D&V, renal failure, peritonitis, burns/CF
Heart failure, kidney disease, liver disease, tumours, medication

Question 5

How do you work out osmolarity?

Answer 5

2 Na + glucose + urea (all in mmol/L)

Question 6

What nonrenal losses can cause hypovolemic hyponatraemia?

Answer 6

GI losses - vomiting, diarrhoea, fistulas, pancreatitis
Excessive sweating
Third sting of fluids - ascites, peritonitis, pancreatitis, burns
Cerebral salt-wasting syndrome

Question 7

What is the treatment for hyponatraemia?

Answer 7

Depends on cause
Fluid restriction
Infusion of hypertonic saline and furosemide can be used in symptomatic patients

Question 8

What should you be careful for in treatment of hyponatraemia?

Answer 8

Pontine demyelination

Can occur with rapid correction of hyponatraemia