Electrolyte disturbance

Question 1

Px of hyponatraemia (

Answer 1

anorexia, nausea, vomiting, headache, irritability,confusion, lethargy, seizures & coma

Question 2

Causes of hypovolaemic hyponatraemia

Answer 2

(↓sodium with relatively ↓water): low urinary sodium concentration & elevated plasma renin activity.

Commonly due to renal sodium losses, diuretic therapy (thiazides), GI sodium losses, vomiting/diarrhoea, skin sodium losses, burns

Question 3

Causes of euvolaemic hyponatraemia

Answer 3

(↑water alone): dilutional form of hyponaetraemia with constant total serum sodium.

Commonly caused by primary polydipsia, excessive electrolyte free water infusion, SIADH (syndorme of inappropriate ADH secretion) & hypothyroidism.

Question 4

Causes of hypervolaemic hyponatraemia

Answer 4

(↑sodium with relatively greater ↑water): also dilutional form due to the relatively greater increase in water than sodium.

Clinical signs include volume expansion; clinically evident edema, ascites & pulmonary edema.

Commonly caused by congestive cardiac failure, cirrhosis, nephrotic syndrome, chronic renal failure.

Question 5

Rx of hyponatraemia

Answer 5

if developed RAPIDLY, infuse hypertonic (3%) sodium chloride with an initial bolus of 100mL, which can be repeated once or twice over initial hours of observation.

If developed SLOWLY, DO NOT give the same dose at once, which can be fatal and produce permanent structural & functional damage to the brain.

Infuse maximum 10mM/day. Also treat the underlying cause.

Question 6

Px of hypernatraemia (>148mM)

Answer 6

lethargy, thirst, reduced cerebral function, dizziness, confusion, weakness, coma & death

Question 7

Causes of hypovolaemic hypernatraemia

Answer 7

(↓sodium with relatively greater loss of ↓water):

e.g. renal sodium losses, diuretic therapy (loop diuretic, osmotic diuretic), glycosuria, GI Na+ losses, colonic diarrhoea, skin sodium losses, excessive sweating

Question 8

Causes of euvolaemic hypernatraemia

Answer 8

(↓water alone):

eg. Diabetes insipidus (central affecting pituitary function or nephrogenic affecting responsiveness of collecitng duct cells to ADH)

Question 9

Causes of hypervolaemic hypernatraemia

Answer 9

(↑sodium with relatively smaller ↑water):

e.g. enteral or parenteral feeding IV or oral salt administration & chronic renal failure.

Question 10

What are the common causes of hypoalbuminaemia?

Answer 10

○ Acute & chronic inflammatory response
○ Nephrotic syndrome (massive proteinuria)
○ Hepatic cirrhosis (reduced hepatic cell mass - reduced albumin synthesis)
○ Heart failure (due to increased volume of distribution. oedema)
○ Malnutrition
○ Burns