Brainscape's Knowledge GenomeTM

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


See full index

Gen Med (Renal) > Clinical Chemistry 1 - Sodium and Water > Flashcards

Clinical Chemistry 1 - Sodium and Water Flashcards

1
Q

The renin-angiotensin-aldosterone system is responsible for the homeostasis of what?

A

Sodium, water and potassium

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

What is released from the juxtaglomerular apparatus of the kidney in response to low renal blood flow or raised sympathetic tone?

A

Renin

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

What is the role of renin?

A

Catalyses the conversion of angiotensin to angiotensin I

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

Angiotensin I is converted to angiotensin II via what?

A

Angiotensin converting enzyme (ACE)

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

What is the role of angiotensin II at the level of the glomerulus?

A

Vasoconstriction of the efferent arteriole

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

What effect does angiotensin II have on the peripheral circulation?

A

Vasoconstriction

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

Angiotensin II promotes the release of what hormone?

A

Aldosterone

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

Where does aldosterone act?

A

On the sodium/potassium pumps of the distal tubule of the nephron

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

What is the action of aldosterone?

A

Sodium and water reabsorption, potassium and hydrogen excretion

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

Sodium concentration in the body is mainly controlled via the action of what?

A

Aldosterone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which group of hormones are responsible for reducing sodium reabsorption at the distal tubule and inhibiting the action of renin, in order to decrease sodium levels in the body?

A

Natriuretic hormones (ANP, BNP, CNP)

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

Raised plasma osmolarity causes thirst via the hypothalamic thirst centre and the release of what hormone?

A

ADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where does ADH exert its effect?

A

Collecting ducts of the nephrons

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

Low plasma osmolarity has what effect on ADH secretion?

A

Inhibition

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

Inappropriately high ADH levels cause excess water reabsorption by the kidney- this leads to what clinical condition?

A

SIADH

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

What are some examples of causes of SIADH?

A

Post-operative stress, small cell lung cancers

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

How can SIADH be treated non-pharmacologically?

A

Restriction of water intake

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What drug class can be used to pharmacologically treat SIADH?

A

V2 vasopressin receptor antagonists (e.g. tolvaptan)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Inadequate vasopressin action leads to what clinical syndrome?

A

Diabetes insipidus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are some causes of cranial (central) diabetes insipidus?

A

Brain tumours or head trauma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the pathology behind cranial (central) diabetes insipidus?

A

The pituitary gland does not release enough ADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the pathology behind nephrogenic diabetes insipidus?

A

The kidney fails to respond to ADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are some electrolyte abnormalities which can lead to nephrogenic diabetes insipidus?

A

Hypokalaemia and hypercalcaemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are some drugs which can lead to nephrogenic diabetes insipidus?

A

Lithium and gentamicin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How do patients with diabetes insipidus present clinically?

A

Polyuria and polydipsia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What happens to plasma osmolarity and plasma sodium levels in diabetes insipidus?

A

High

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What happens to urine osmolarity and urine sodium levels in diabetes insipidus?

A

Low

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the clinical test to diagnose diabetes insipidus?

A

Water deprivation test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

In which type of diabetes insipidus will synthetic vasopressin cause a rise in urine osmolarity?

A

Cranial (central)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

ADH levels are high in which type of diabetes insipidus?

A

Nephrogenic

31
Q

ADH levels are low in which type of diabetes insipidus?

A

Cranial (central)

32
Q

How is cranial (central) diabetes insipidus treated?

A

Intranasal desmopressin

33
Q

What effect does Addison’s disease have on sodium, water and potassium levels?

A

Hyponatraemia, hypovolaemia, hyperkalaemia

34
Q

What effect do diuretics have on sodium levels?

A

Hyponatraemia

35
Q

What effect does excess aldosterone levels (for whatever reason) have on sodium, water and potassium levels?

A

Hypernatraemia, hypervolaemia, hypokalaemia

36
Q

What effect does renal failure have on sodium levels?

A

Hypernatraemia

37
Q

Which electrolyte abnormality always causes hyperosmolarity?

A

Hypernatraemia

38
Q

Most hypernatraemia arises from what?

A

Unreplaced water loss

39
Q

The body volume in hypernatraemia is usually what?

A

Low

40
Q

What is the body’s main defence against hypernatraemia?

A

Thirst

41
Q

What are some potential causes of hypernatraemia?

A

Fluid losses (D&V, burns), diabetes insipidus, primary hyperaldosteronism

42
Q

What is a potential iatrogenic cause of hypernatraemia?

A

Excessive saline as IV fluid replacement

43
Q

The early clinical features of hypernatraemia are caused by what?

A

Increased excitability of neurons

44
Q

What are some examples of early neurological features of hypernatraemia?

A

Irritability, muscle twitches, brisk reflexes, spasticity

45
Q

What are some examples of non-neurological features that may be experienced by someone with hypernatraemia?

A

Thirst, lethargy and weakness

46
Q

What can hypernatraemia lead to if left untreated?

A

Seizures and coma

47
Q

How is hypernatraemia treated if the patient is clinically well?

A

Oral water replacement

48
Q

Generally, how is hypernatraemia managed?

A

Water replacement and treatment of the underlying cause

49
Q

How is hypernatraemia treated if the patient is clinically unwell?

A

IV 5% dextrose solution (1 litre every 6 hours)

50
Q

If a patient with hypernatraemia is hypovolaemic, what should be used for fluid replacement?

A

IV 0.9% saline

51
Q

Which type of fluids should always be avoided in patients with hypernatraemia?

A

Hypertonic solutions

52
Q

It is important not to correct sodium levels too quickly. You should aim for a change of no more than how many mmol/hour?

A

0.5mmol/hour

53
Q

It is important not to correct sodium levels too quickly. You should aim for a change of no more than how many mmol/day?

A

12mmol/day

54
Q

If a patient with hyponatraemia is dehydrated, is the cause too little sodium or too much water?

A

Too little sodium

55
Q

If a patient with hyponatraemia is not dehydrated, is the cause too little sodium or too much water?

A

Too much water

56
Q

If you have established that a person is hyponatraemic due to too little sodium, what is the next most important test to check to establish the diagnosis?

A

Urinary sodium levels

57
Q

If a patient is hyponatraemic, dehydrated and has a urinary sodium level of > 20mmol/l, this suggests sodium is being lost from the kidneys. What are some potential causes of this?

A

Addison’s disease, CKD, diuretic overuse

58
Q

If a patient is hyponatraemic, dehydrated and has a urinary sodium level of < 20mmol/l, this suggests sodium is being lost from somewhere other than the kidneys. What are some potential causes of this?

A

D&V, burns, small bowel obstruction, fistulae

59
Q

When a patient is hyponatraemic, what is the first thing that you want to establish?

A

Are they dehydrated or not

60
Q

When a patient is hyponatraemic and not dehydrated, you know that the cause is too much water. In these cases, what is the first question you should ask yourself?

A

Is the patient oedematous

61
Q

If a patient is hyponatraemic, not dehydrated and is oedematous, what is the likely underlying cause?

A

An oedema syndrome (e.g. cardiac, renal or hepatic failure)

62
Q

If a patient is hyponatraemic, not dehydrated and not oedematous- what is the next test that you should look at to establish the diagnosis?

A

Urine osmolality

63
Q

If a patient is hyponatraemic, not dehydrated or oedematous and has a urine osmolality of > 100mg/kg, what is the likely underlying cause?

A

SIADH

64
Q

If a patient is hyponatraemic, not dehydrated or oedematous and has a urine osmolality < 100mg/kg, what is the likely underlying cause?

A

Fluid overload

65
Q

Which patients are most vulnerable to the neurological effects of hyponatraemia?

A

Extremes of age, menstruating women and those with underling neurological or metabolic disorders

66
Q

What effect does hyponatraemia have on the nervous system?

A

Depressed function

67
Q

What are some neurological symptoms of hyponatraemia?

A

Confusion, muscle cramps, reduced reflexes

68
Q

What are some non-neurological symptoms of hyponatraemia?

A

Lethargy, nausea

69
Q

There is a risk of seizures and coma with hyponatraemia, particularly when sodium levels fall below what?

A

120mmol/l

70
Q

What is the risk of treating hyponatraemia too quickly?

A

Central pontine myelinosis

71
Q

How is asymptomatic, chronic hyponatraemia treated?

A

Fluid restriction and treatment of the underlying cause

72
Q

How is acute or symptomatic hyponatraemia treated?

A

Cautious rehydration with 0.9% saline

73
Q

If a patient with hyponatraemia is having a seizure or is in a coma- urgent help is needed. What can be considered as treatment?

A

Hypertonic saline +/- furosemide

74
Q

What drug can be useful in the treatment of hypervolaemic or euvolaemic hyponatraemia?

A

Tolvaptan

Gen Med (Renal) (18 decks)

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