sodium/ water states Flashcards

1
Q

hypotonic hyponatraemia versus non-hypotonic hyponatraemia= plasma osmolality levels

A

hypotonic hyponatraemia= <275 (urine osmolality >100)

non-hypotonic hyponatraemia >275 (urine osmolality <100)

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2
Q

what are non-hypotonic causes of hyponatraemia 5

A
ethanol- beer potonmania
hyperglycaemia
pseudohypo-natraemia
low sodium intake
polydipsia
=pure water gain
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3
Q

what is pseudohyponatraemia

A

paraproteinaemia causes it

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4
Q

2 ways of classifying hyponatraemia

A
  1. ECF- hypo, euv, hypervolaemia

2. urine osmolality <20 or >20

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5
Q

causes of hypervolaemia hyponatraemia with a urinary sodium <30 5

A

Increased interstitial salt

  • liver failure
  • cirrhosis
  • hepato-renal syndrome
  • CCF-cardiac
  • nephrotic syndrome
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6
Q

mechanism behind hypervolaemic hyponatraemia with <20 urine sodium

A

due to the above diseases- blood pressure drops

  • causes release of AVP which causes salt and water to be retained
  • but more water retained than salt
  • salt and water excess
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7
Q

causes of euvolaemic hyponatraemia with urine osmolality < serum

A
(aka trick question= non-hypotonic hyponatraemia)
water intoxification
-polydipsia
-beer potomaina 
water overload
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8
Q

causes of euvolaemic hyponatraemia with urine osmolality >serum or urine sodium >30
7

A
  1. SIADH
  2. secondary adrenal insufficiency
  3. hypothyroidsim- myxoedema
  4. lung disease
  5. cancer-siadh small cell
  6. chest
  7. CNS
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9
Q

causes of hypovolaemic hyponatraemia with urine sodium <30 3 main ones

A
pre renal: sodium loss in excess of water
GI loss
3rd space losses
previous diuretic use 
-diarrhoea
-sweat
-vomiting 
-burns
-fistula
-cirrhosis
-SBO
-villous adenoma rectum
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10
Q

causes of hyponatraemia hypovolaemic with urine sodium >30 4

A

renal?: salt and water lost through kidney but more salt loss than water

  • kidney failure
  • addison’s-primary adrenal failure
  • vomiting
  • CSWS
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11
Q

treatment for each type of hyponatraemia

A

hypervolaemic: restrict salt and water
euvolaemic: restrict water
hypovolaemic: give salt and water

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12
Q

2 body compartments

A
  • extracellular: intravascular and intercellular

- intracellular

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13
Q

what compartments should sodium and potassium be found in

A

sodium=extracellular (so plasma sodium good estimate)

potassium- intracellular (so plasma potassium bad estimate eg in DKA)

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14
Q

hyponatraemia complication of going down too low and the symptoms

A

=cerebral oedema

  • nausea, vomiting, headache and confusion
  • reduced consciouscness
  • 6th nerve palsy
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15
Q

hyponatraemia complication of coming up too quickly

A

=central pontine myelinolysis (osmotic demyelination) affects brain stem

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16
Q

symptoms of central pontine myelinolysis

A
dysarthria
mutism
dysphagia
lethargy
mood change
spasitc quadriparesis
seizure
coma
death 
neuro (focal, cranial, bulbar signs)
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17
Q

when does central pontine myelinolysis appear

A

3-4 days after sodium corrects

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18
Q

how does hyperglycaemia cause hyponatraemia

A

glucose level high increases osmolality
-> so body pushes sodium down to maintain osmolality level
seen in DKA

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19
Q

classification of mild, moderate and profound hyponatraemia

A

mild: 130-135
moderate: 125-129
severe <125

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20
Q

moderately severe symptoms of hyponatraemia

A

nausea without vomiting, confusion headache

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21
Q

severe symptoms of hyponatraemia

A

vomiting
cardio-resp distress
abnormal and deep somnolence seizure
coma

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22
Q

difference between acute and chronic hyponatraemia and risks

A

acute: develops <48 hours- more at risk of cerebral oedema
chronic: develops >48 hours more at risk of pontine myelinolysis on repletion

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23
Q

guideline for use of hypertonic fluid for hyponatraemia

A

-300mls of sodium chloride 1.8% over 30 minutes=hypertonic
-needs urgent treatment
-monitor sodium aim for a 5mmol/l increase in na with no more than 10mmol/l rise in 1st 24 hrs
then 8mmol/l rise every 24 hrs after
-not for hypervolaemic

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24
Q

what should not be used for a hypovolaemic hyponatraemic patient treatment

A

hypertonic sodium chloride due to already volume depletion

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25
Q

mangement of hypovolaemic hyponatraemia

A

-fluid but no more than 10mmol/l in first 24 hours

-use an isotonic fluid for resuscitation eg normal saline 0.9% or Hartman or
plasmalyte
-check sodium 4 hourly at least

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26
Q

how is hypovolaemia diagnosed

A
clinical diagnosis
tachycardia
hypotension
absent JVP
postural hypotension
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27
Q

what is management of hyponatraemia based on 2

A

acute or chronic development

prescence of neurological symptoms

28
Q

management of euvolaemic hypervolaemia

A

restrict water

29
Q

management of hypervolaemic hyponatraemia

A

restrict salt and water

30
Q

key difference between CSWS and SIADH

A

CSWS=hypovolaemic

SIADH=euvolaemic

31
Q

what causes CSWS

A

cerebral salt wasting syndrome

sub-arachnoid haemorrhage

32
Q

management of CSWS

A

hypovoleamic so give normal saline sodium chloride 0.9%

33
Q

management of SIADH

A

euvolaemic so restrict water

34
Q

diagnoses of SIADH 6 steps

A
  1. hypo-osmolality <275 or plasma sodium <135
  2. inappropriate urinary concen. >100mosmo
  3. patient euvolaemic
  4. elevated urinary sodium >30 with normal intake
  5. exclude hypothyroidism, steroid deficiency through SST and diuretic use
  6. normal renal and cardiac function
35
Q

causes of SIADH 5

A
  1. drugs related
  2. pulmonary
  3. tumours
  4. CNS disorders
  5. others
36
Q

drug related causes of SIADH 3

A
  1. stimulate ADH-nicotine, antidepressants, dopamine agonists, MDMA
  2. potentiate ADH: DDAVP, cyclophosphamide
  3. ACEI and PPI-omeprazole
37
Q

pulmonary causes of SIADH

A
  1. infection: tb, pneumonia

2. mechanical/ ventilators: ARDS, COPD

38
Q

tumour causes of SIADH 5

A
pulmonary
mediastinal
small cell cancer
duodenum
pancreas
39
Q

CNS disorder causes of SIADH 6

A
  1. mass lesions
  2. inflammatory disease
  3. degenerative disease
  4. trauma- subarachnoid haemorrhage
  5. psychosis
  6. transsphenoidal adenomectomy
40
Q

what is the triple phase response of transsphenoidal adenomectomy

A
  1. CDI
  2. remission or SIADH
  3. then recurrence of permanent DI
41
Q

other cause of SIADH 3

A
  1. aids
  2. strenuous exercise
  3. idiopathic
42
Q

management of SIADH 8

A
  1. withold meds
  2. identify and treat underlying cause
  3. obtain CXR in all patients with SIADH
  4. CT
  5. restrict fluid 800-100ml per day
  6. oral demeclocycline
  7. loop diuretic and oral sodium chloride alternative
  8. tolvaptan v2 receptor antagonist for euvolaemic or hypervolaemic not hypovolaemic
43
Q

management if hyponatraemia is corrected too quickly

A

discontinue active treatment
consult for sodium free IV infusion of 10ml/kg body weight
-Desmopressin DDAVP 2mcg

44
Q

causes of hypernatraemia

A

pure water loss

water gain

45
Q

hypernatraemia symptoms

A
reduced cerebral function
dehydration
dizziness
confused
weak
coma
46
Q

hypovlaemic causes of hypernatraemia

A
haemorrhage
vomit
diarrhoea
burns
diuretic state
fever
hyperventilation
47
Q

iatrogenic causes of hypernatraemia

A

diuretic therapy

high sodium intake

48
Q

reduced water intake causes of hypernatraemia

A

psychosocial-elderly
glycosuria
excessive sweating

49
Q

euvolaemic causes of hypernatraemia

A

water deficit alone

Diabetes insipidus

50
Q

hypervolaemic causes of hypernatraemia

A

enteral feeds
IV salt
chronic renal failure

51
Q

management of hypernatraemia

A

acute= iv fluid isotonic 6% dextrose or hypotonic 0.45% saline

52
Q

causes of polyuria 4

A
  1. DI
  2. habitual psychogenic
  3. osmotic diuresis (from glucose DM), mannitol, hypercalcaemia
  4. renal impairment
53
Q

definition of polyuria

A

urine rate >2ml/kg/hour

54
Q

what receptors does ADH act on in the kidney

A

v2 receptors

55
Q

causes of cranial DI 4

A
inadequate ADH release
congenital
pituitary/ hypot
head injury
intracranial infection
56
Q

nephrogenic DI causes
AND 2 drugs

7

A
renal insensitivity
congenital
hypercalcium
hypopotasium
obstructive uropathy
chronic renal failure
drugs
-lithium
-demeclocycline (for SIADH)
57
Q

criteria for DI

A

polyuria that is hypotonic <600mosmol/kg when plasma is hypertonic >300mosmol/kg

58
Q

conditions for the water deprivation test 3

A

during test for 8 hours

  • no fluids and dry snacks
  • hourly weight, bp and urine sample
  • 2 hourly blood
  • then give DDAVP
59
Q

what would the results be for a water deprivation test for cranial DI
-after dehydration
then
-after giving DDAVP

A
  • <300 after dehydration (no ADH so cant stop loosing water so urine osmolality low)
  • after ddavp >600 as stop loosing water
60
Q

water deprivation test for nephron DI

A

<300 after dehdration and after DDAVP as problem with the receptors

61
Q

what would be the result for partial DI

A

after dehydration would be 300-600

and then after ddavp would be <600

62
Q

treatment of DI cranial

A

give DDAVP ie desmopressin

63
Q

treatment of DI nephrogenic

A
  • thiazide diuretic/ amiloride diuretic to cause increased sodium excretion and water
  • indomethacin to lower intra-renal prostaglandins that oppose ADH
  • low salt and low protein diet
64
Q

treatment for partial DI

A

use meds that promote SIADH eg chlopropamide which may upregulate renal ADH receptors when ADH partially deficient

65
Q

pathway of ADH release

A
high plasma osmolality ->
adh release
-> 
kidney v2 receptors
-> concentrates and retains water
66
Q

signs of dehydration

A
  • absent jvp
  • dry mucosal membranes
  • postural hypotension
  • tachycardia
  • thirst
  • reduced skin turgor
  • supine hypotension
  • oligouria
  • organ failure
  • dizziness
  • dysphagia
67
Q

signs of volume excess

A
  • hypertension
  • tachycardia
  • raised jvp
  • nausea
  • gallop rhythm
  • oedema
  • third space gain