Hypernatraemia Flashcards

1
Q

major cause of hypernatraemia

A

Na+ concentration due to water loss

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2
Q

disease states which can cause hypernatraemia

A

haemorrhage
vomiting
diarrhoea
burns
diuretics states
sequestration
renal disease
excess sweat due to fever
hyperventilation
diabetes insipidus
reduced water intake
increased sodium intake

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3
Q

function of vasopressin/ADH

A

stimulates aquaporin channels to migrate to cell surface in collecting duct
more water is reabsorbed
urine is more concentrated
happens when you are thirsty/volume deplete

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4
Q

pathophysiology of SIADH

A

ADH secretion is excessive
it is not suppressed by already have enough water in body (reduced tonicity)
too much water is reabsorbed
Na+ gets diluted in body = hyponatraemia

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5
Q

causes of SIADH

A

neurological - stroke, encephalitis, meningitis, head injury, stroke
malignancy
drugs

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6
Q

pathophysiology of diabetes insipidus

A

ADH is insufficient or inactive
water loss in urine is not controlled
not enough is reabsorbed
Na+ gets concentrated = hypernatraemia
no ADH able to respond so continued fluid loss

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7
Q

what psychiatric drug can cause diabetes insipidus and what type

A

nephrogenic
lithium carbonate
used for bipolar disorder

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8
Q

what investigations should be done for hypo/hypernatraemia

A

electrolytes
FBC
infection screen
CXR
serum cortisol
CT/MRI brain
plasma osmolality
urine osmolality
urine sodium concentration

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9
Q

what disease would a low serum cortisol suggest

A

addison’s

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10
Q

treatment of hyponatraemia

A

water restriction
treat underlying cause or stop offending drug
allow time

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11
Q

why are Na+ supplements not used for hyponatraemia

A

it just makes patients more thirsty

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12
Q

hypernatraemia treatment

A

give water
e.g. as 5% dextrose IV
treat underlying cause or stop offending drug
allow time

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13
Q

cranial diabetes insipidus treatment

A

synthetic ADH

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14
Q

cranial diabetes insipidus treatment

A

synthetic ADH (desmopressin)

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15
Q

nephrogenic diabetes insipidus treatment

A

supraphysiological ADH
diuretics
NSAIDs

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16
Q

what can occur if you correct hyponatraemia too rapidly

A

central pontine myelinolysis

17
Q

what is the recommended rate of correction of hyponatraemia

A

4-10mmol/l/day if asymptomatic
8-12mmol/l/day if symptomatic

18
Q

signs of volume depletion/dehydration

A

postural hypotension
tachycardia
absence of JVP @ 45 degrees
reduced skin turgor
dry mucosae
supine hypotension
oliguria
organ failure

19
Q

symptoms of volume depletion/dehydration

A

thirst
dizziness
dysphagia
weakness
confusion
aggression
coma

20
Q

signs of volume excess/overhydration

A

hypertension
tachycardia
raised JVP @ 45 degrees
gallop rhythm
oedema
organ failure

21
Q

symptoms of volume excess/overhydration

A

nausea
localised discomfort
dyspnoea
confusion
aggression
coma

22
Q

what does a visible JVP at 45 degrees suggest

A

huge pressure in the right atrium

23
Q

causes of visible JVP

A

heart failure
excess fluid
stenosis

24
Q

what do you do if you can’t see the JVP at 45 degrees

A

press on liver

25
Q

how do you check for oedema

A

press down for 30s
oedema will displace
fat will not