hypernatraemia/hyponatraemia

Question 1

what does significant hyperglycaemia do to sodium levels

Answer 1

causes hyponatraemia
due to shift of water out of cells

Question 2

hypervolemic hyponatraemia may be caused by

Answer 2

heart failure
liver cirrhosis
kidney failure
nephritic syndrome

Question 3

euvolaemic hyponatraemia may be caused by

Answer 3

SIADH
hypothyroidism
psychogenic polydipsia
pain
nausea
secondary renal insufficiency

Question 4

hypovolaemic hyponatraemia

Answer 4

sodium loss with free water intake
- vomiting/ddiarhhoea
- burns
thiazids
hypopituitarism
primary adrenal insufficiency

Question 5

decreases in blood pressure are detected by

Answer 5

baroreceptor cells in the carotid sinuses or the aortic arch
or
the juxtaglomrular cells
or
sympathetic nerves getting activted
or
the macula densa cells sensing less sodium and chloride

Question 6

what happens in response to low blood pressure

Answer 6

kidneys secrete renin which converts angiotensinogen to angiotensin 1

Question 7

what does ACE to

Answer 7

the ngiotensin converting enzyme conveerts angiotensin 1 to angiotensin 2

Question 8

what does angiotensin 2 do

Answer 8

1. causes the efferent arteriole to constrict more than the afferent arteriole, this increases GFR
2. directly stimulates sodium hydrogen exchanger, this causes proximal tubule to reabsorb more sodium ions from the filtrate
3. stimulates the adrenal cortex to secrete aldosterone

Question 9

action of aldosterone

Answer 9

1. increases sodium resorption and potassium secretion
2. stimulates pituitary to release ADH
3. stimulates hypothalamus to increase thirst

Question 10

fast and slow action of the RAAS system to increase blood pressure

Answer 10

fast: angiotensin 2 constricts blood vessels to increase BP
slow: aldosterone reabsorbs sodium and water to increase fluid volume

Question 11

what does ADH do

Answer 11

increases water reabsorption

Question 12

RAAS system is inhibited by the

Answer 12

natriuretic peptides

Question 13

SIADH is likley when

Answer 13

SIADH is likely when
serum sodium low
serum osmolality low
urine osmolality high
urine sodium high

Question 14

treatment of hypovolaemic hyponatraemia

Answer 14

IV NaCl 0.9%
with potassium supplements if required

Question 15

what might be the harm of rapid correction of hyponatraemia

Answer 15

may produce permanent central nervous system injury, due to osmotic demyelination

Question 16

symptoms of hypernatraemia

Answer 16

lethargy, confusion and coma
due to depletion of intracerebral fluid

Question 17

symptoms of hyponatraemia

Answer 17

generally asymptomatic when mild
mental confusion, gait disturbance, impaired consciousness and seizures increase with the severity of hyponatraemia

Question 18

causes of hypernatramia

Answer 18

water loss/inadequate replacement of water: diabetes insipidus, thiazides, GI water loss, severe burns
sodium overload

Question 19

treatment of hypernaatraemia

Answer 19

correct the cause and replace any fluid deficit
oral fluids are safest
IV fluids glucose 5% may be needeed