Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PathY5 > Sodium Balance > Flashcards

Sodium Balance Flashcards

1
Q

What is the most common electrolyte imbalance in hospital?

A

Hyponatraemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the boundary for hyponatraemia?

A

<135mmol/L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the underlying pathogenesis of hyponatraemia?

A

Increased extracellular water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which hormone controls water balance?

A

ADH (vasopressin) water retention via AQ2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What do V1 and V2 receptors do?

A

V1: AQ2 in CD
V2: Vasc. smooth muscle, vasoconstriction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the two main stimuli for ADH secretion?

A

High Serum osmolality (hypothalamic osmoreceptors)

Low Blood volume/ pressure (Mediated by baroceptors in carotids/ atria/ aorta)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the effect of increased ADH secretion on serum sodium?

A

Hyponatraemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does increased water reabsorption cause?

A

Reduced sodium concentration in the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the first step in the clinical assessment of a patient with hyponatraemia?

A

Assess volume status: Hypo/ Eu/ Hypervolaemic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the clinical signs of hypovolaemia?

A 
Tachycardia
Postural hypotension
Dry mucous membranes
Reduced skin turgor
Confusion/drowsiness
Reduced urine output
Low urine Na+ (<20) (most reliable)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the clinical signs hypervolaemia?

A

Raised JVP
Bibasal crackles (on chest examination)
Peripheral oedema

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the causes of hypovolaemic hyponatraemia?

A 
GI/renal loss:
Diarrhoea
Vomiting
Diuretics
Salt losing nephropathy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the causes of euvolaemic hyponatraemia?

A

Endocrine:
Hypothyroidism
Adrenal insufficiency
SIADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the causes of hypervolaemic hyponatraemia?

A

Failures:
Cardiac Failure
Cirrhosis
Nephrotic syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the causes of SIADH?

A

CNS pathology

Lung pathology

Drugs (SSRI, TCA, opiates, PPIs, carbamazepine)

Tumours

Surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How might you investigate the euvolaemic causes of hyponatraemia?

A

Thyroid: TFTs
Renal insufficiency: Short Synacthen test
SIADH: Plasma & urine osmolality (low plasma & high urine osmolality)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do you diagnosis SIADH?

A 
No Hypovolaemia
No Hypothyroidism
No Adrenal insufficiency
Reduced plasma osmolality AND
Increased urine osmolality (>100)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How would you manage a hypovolaemic patient with hyponatraemia?

A

Volume replacement with 0.9% saline

19
Q

How would you manage a hypervolaemic patient with hyponatraemia?

A

Fluid restriction 500ml-1hr/24 hr

Treat the underlying cause

20
Q

How would you manage a euvolaemic patient with hyponatraemia?

A

Fluid restriction 500ml-1hr/24 hr

Treat the underlying cause

21
Q

What happens/ how do you manage in severe hyponatraemia?

A

Reduced GCS
Seizures
Seek expert help (Treat with Hypertonic 2.75-3% saline)

22
Q

What is the most important point to remember while correcting hyponatraemia?

A

Serum Na must NOT be corrected > 8-10 mmol/L in the first 24 hours

Risk of osmotic demyelination (central pontine myelinolysis)
quadriplegia, dysarthria, dysphagia, seizures, coma, death

23
Q

How do you treat SIADH (With drugs)?

A

Demeclocycline

Tolvaptan

24
Q

How does Demeclocycline work?

A

Reduces responsiveness of collecting tubule cells to ADH

Monitor U&Es (risk of nephrotoxicity)

25
Q

How does Tolvaptan work?

A

V2 receptor antagonist

26
Q

What is the boundary for hypernatraemia?

A

> 145 mmol/L

27
Q

What are the main causes of hypernatraemia?

A

Unreplaced water loss (GI loss/ renal loss, sweat, DI)

Cannot control water intake (child/ elderly)

28
Q

What investigations would you order in a patient with suspected diabetes insipidus?

A

Serum glucose (exclude diabetes mellitus)

Serum potassium (exclude hypokalaemia) - causes ADH resistance

Serum calcium (exclude hypercalcaemia) - causes ADH resistance

Plasma high & urine low osmolality

Water deprivation test

29
Q

How would you treat hypernatraemia?

A 
Fluid replacement (dextrose)
Treat the underlying cause
30
Q

How do you manage hypernatraemia in hypovolaemic patients?

A

5% dextrose (correct water deficit)

0.9% saline (correct EC fluid volume depletion)

Measure Na every 4-6 hours

31
Q

What are the effects of diabetes mellitus on serum sodium?

A

Variable

32
Q

What may happen in DM which changes serum sodium?

A

Hyperglycaemia draws water out of the cells leading to hyponatraemia

Osmotic diuresis in uncontrolled diabetes leads to loss of water and hypernatraemia

33
Q

What does increased osmolality cause other than a release of ADH?

A

Thirst

34
Q

Why does vomiting cause hyponatraemia?

A

Vomiting causes blood volume drop which stimulates water retention which dilutes sodium in the blood

35
Q

What is the most reliable clinical sign of hypovolaemia?

A

Low urine sodium (<20)- needs to be assessed ASAP

36
Q

Is urine sodium low in hypervolaemia?

A

Yes- hyperaldosteronism caused by HF etc. causes sodium retention

37
Q

Why does hypothyroidism cause hyponatraemia?

A

Reduced BP (contractility/ HR) causes more ADH

38
Q

How long does it take for symptoms to arise in central myelinolysis?

A

A few days- if they look fine after a day and the sodium has jumped up by 20 mmol/L in one day- THEY ARE NOT FINE and you MUST bring it back down

39
Q

When does central myelinolysis happen?

A

When sodium jumps up more than 8-10 mmol/L

40
Q

How often should sodium be checked?

A

Every 2-4 hours

41
Q

How does SIADH have high sodium in urine?

A

SIADH causes expansion of atria which releases natriuretic peptides

This causes natriuresis (loss of sodium into the urine)

42
Q

What is water?

A

‘5% dextrose is water’

????

43
Q

What is pseudohyponatraemia?

A

Low Na, normal osmolality and caused by change in proteins/ lipids )e.g. paraproteinaemia)

PathY5 (98 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions