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Sodium Disorders Flashcards

1
Q

Which two electrolytes often have to be ordered separately/not part of CMP?

A

Mg and PO4

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2
Q

TBW = x% of body weight

A

60%

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3
Q

ICF makes up ____ of body water

A

2/3

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4
Q

In infants, water is ___ % of body weight. In elderly, water is _____%

A

infants: 80%

Elderly: 45%

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5
Q

Obesity has what effect on total body water?

A

decreased

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6
Q

TIE 60, 40, 20 means…

A

Total body fluid: 60%

Intracellular: 40%

Extracellular: 20%

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7
Q

This is the total solute concentration in a fluid compartment as determined by sodium, glucose and urea

A

Osmolality

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8
Q

How is osmolality calculated?

A

(2*sodium) + (Glucose/18) + (BUN/2.8)

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9
Q

Symptoms occur when osmolality is greater than ____ or less than ____

A

> 320

< 265

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10
Q

The below substances (are/aren’t) included in lab calculated osmolarity…

mannitol, protein, ethanol, methanol, ethylene glycol

A

aren’t

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11
Q

High amounts of osmotically active substances can lead to an elevated…

A

osmolar gap

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12
Q

This is the ability of solutes to drive water from one compartment to another…

A

tonicity

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13
Q

Tonicity has major effects on …

A

size of cells

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14
Q

decreased sodium results in shift of water from ECF to ICF. This can cause what severe manifestation?

A

swelling of brain cells

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15
Q

The total amount of which electrolyte in the ECF is the major determinant of the extracellular fluid volume…

A

sodium

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16
Q

This is the amount of water relative to sodium in ECF, not total body sodium

A

Serum sodium

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17
Q

Abnormal serum sodium is a sign of a disorder in what?

A

water regulation

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18
Q

The ECFV is determined by…

A

overall volume status of patient

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19
Q

An abnormality in the size of the ECFV is a marker of what?

A

abnormal sodium control

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20
Q

high ECFV indicates…

A

too much sodium

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21
Q

high serum sodium indicates

A

too little water relative to sodium

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22
Q

With sodium disorders, a patients volume status must be determined. What are the three volume statuses?

A

hypovolemic
euvolemic
hypervolemic

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23
Q

Volume losses or sequestration via intestinal obstruction, pancreatitis, rhabdo can cause what volume status?

A

hypovolemia

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24
Q

Patient presents with the following, making you concerned for what volume status?

increased thirst
decreased turgor
dry mucous membranes
oliguria
CNS depression
muscle cramps/weakness
hypotension
increased pulse
A

Hypovolemia

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25
Q

The following are causes of what fluid status?

liver disease
CHF
renal failure
nephrotic syndrome
primary hyperaldosteronism
cushings
pregnancy
A

hypervolemia

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26
Q

A patient presents with the following sxs, making you concerned for what volume status?

edema
SOB
orthopnea/PND
JVD
hepatojugular reflux
crackles
A

hypervolemia

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27
Q

Thirst and ADH influence…

A

water retention

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28
Q

RAAS, ANP, catecholamines influence

A

salt retention

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29
Q

This hormone…

increases renal sodium reabsorption

increases renal potassium secretion

A

aldosterone

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30
Q

Hyponatremia becomes dangerous when it drops below…

A

125

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31
Q

What is the most common electrolyte abnormality in hospitalized patients?

A

hyponatremia

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32
Q

Serum sodium under what value indicates hyponatremia?

A

< 135

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33
Q

Presence of sxs in hyponatremia depend on what?

A

level of cerebral edema

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34
Q 
HA
NV
Lethargy
Weakness
Confusion
respiratory distress
Seizures

these all indicate…

A

hyponatremia

35
Q

What are three general types of hyponatremia?

A

pseudo

redistributive

hypovolemic/hypervolemic/euvolemic

36
Q

What type of hyponatremia?

Serum sodium < 135, but normal osmolality

occurs with hyperlipidemia and hyperproteinemia

laboratory artifact

A

pseudohyponatremia

37
Q

What type of hyponatremia?

hyperosmolar state

caused by osmotically active substances in ECF

MC cause by hyperglycemia

A

redistributive hyponatremia

38
Q

How do you correct sodium in redistributive hyponatremia?

A

add 1.5 mEq/L to sodium for every 100mg/dl serum glucose over 100mg/dl

39
Q

The following are causes of what type of hyponatremia?

liver, heart, renal failure

A

hypervolemic hyponatremia

40
Q

What tx is indicated for hypervolemic hyponatremia?

A

diuretics, dialysis, fluid restriction

41
Q

What type of hyponatremia?

Caused by:
cerebral salt wasting
renal tubular acidosis
diuretics

A

hypovolemic hyponatremia urine sodium > 20

42
Q

what type of hyponatremia?

caused by:
gastroenteritis

third space losses (burns, pancreatitis, etc)

A

hypovolemic hyponatremia

urine sodium < 20

43
Q

What type of hyponatremia?

caused by:

  • SIADH
  • Psychogenic polydipsia
  • hypothyroidism
  • adrenal insufficiency
A

euvolemic hyponatremia

44
Q

How do you treat euvolemic hyponatremia?

A

fluid restriction, tx of underlying cause

45
Q

A patient presents with:

concentrated urine (> 100) with low serum osmolality and euvolemia

46
Q

This disease occurs with impaired free water excretion, but normal sodium excretion

47
Q

What labs should be ordered to determine the underlying cause of SIADH?

A

CT/MRI (CNS)
CXR (lung)
medication list

48
Q

The below Bartter and Shwartz Criteria diagnoses what condition?

  1. decreased plasma osmolality
  2. concentrated urine
  3. elevated urine sodium
  4. euvolemia
  5. normal cortisol and thyroid, no diuretics
49
Q

How do you treat SIADH?

A

fluid restriction

50
Q

What are the first look labs when evaluating hyponatremia?

A

serum sodium, osmolarity

urine sodium, osmolarity

51
Q

what are the second look labs when evaluating hyponatremia?

A

TSH, cortisol

52
Q

What must be evaluated from the very start in hyponatremia?

A

fluid status

53
Q

Hospitalization of a hyponatremic patient should occur if one of what two factors is present?

A

sodium < 125

symptomatic

54
Q

rapid increase in serum sodium can lead to what condition?

A

cerebral pontine myelinolysis (CPM)

55
Q

The rate of sodium correction should be ____ in the first 24 hours, not to exceed _____

A

4-6 mEq/L

not to exceed 8 mEq/L

56
Q

Is a daily or hourly change associated with CPM?

57
Q

How often should you check serum sodium when you are replacing it to ensure you are not overcorrecting?

58
Q

A patient presents with the following, concerning for what irreversible condition

1-3 days after hospitalization

dysarthria, dysphagia
seizures
AMS
quadriparesis
hypotension
59
Q

Hyponatremia with high osm. often indicates…

A

hyperglycemia

60
Q

hyponatremia with normal osm. often indicates

A

pseudohyponatremia

61
Q

hyponatremia with normal/low urine osmolality often indicates…

A

water intoxication

62
Q

Hyponatremia with the following often indicates…

  • low serum osmolality
  • high urine osmolality
  • hypervolemia
A

CHF

Liver/renal failure

63
Q

Hyponatremia with the following often indicates…

  • low serum osmolality
  • high urine osmolality
  • euvolemia
A

SIADH
hypothyroid
adrenal insufficiency

64
Q

Hyponatremia with the following often indicates…

  • low serum osmolality
  • high urine osmolality
  • hypovolemia
  • urine sodium < 10
A

vomiting, diarrhea

65
Q

Hyponatremia with the following often indicates…

  • low serum osmolality
  • high urine osmolality
  • hypovolemia
  • urine sodium > 20
66
Q

Serum sodium > 145 indicates…

A

hypernatremia

67
Q

What causes the clinical features in hypernatremia?

A

brain shrinkage

68
Q

The following can cause…

too little water
too much dietary salt
excess water loss

A

hypernatremia

69
Q

Hyperglycemia, increased mannitol can cause _____ which contributes to hypernatremia

A

osmotic diuresis

70
Q

A patient presents with:

asymptomatic
thirst
AMS
weakness
neuromuscular irritability
focal neurologic deficit
seizure
A

hypernatremia

71
Q

sxs of hypernatremia are related to…

A

rate of onset

72
Q

The vast majority of cases of hypernatremia are due to…

A

GI, skin, renal water loss

73
Q

how does the body usually compensate for water loss?

A

increase thirst

maximally concentrate urine

74
Q

This disorder…

nonosmotic urinary water loss

elevated serum sodium

dilute urine when should be concentrated

A

Diabetes insipidus

75
Q

Diabetes insipidus is a problem with what hormone, leading to collecting ducts being impermeable to water, and therefore not reabsorbed?

76
Q

impaired secretion of ADH indicates what type of diabetes insipidus

77
Q

lack of kidney response to ADH despite adequate presence of ADH indicates what type of diabetes insipidus?

A

nephrogenic

78
Q

The following are acquired causes of what?

  • chronic renal insufficiency
  • tubulointerstitial renal dz
  • amyloidosis
  • lithium toxicity
A

nephrogenic DI

79
Q

the below are treatments for what condition?

thiazides
amiloride
chlorpropamide
indomethacin

A

nephrogenic DI

80
Q

What are three approaches to treating hypernatremia?

A

hospitalization if severe
stop water loss
replace water deficit

81
Q

what is a precaution to replacing water deficit?

A

dont do it too rapidly, can cause CPM

82
Q

In order to replace free water in hypernatremia, what must be calculated?

A

water deficit

83
Q

how do you calculate water deficit?

A

deficit = normal TBW - current TBW

84
Q

current TBW is calculated by…

A

normal serum na x normal TBW/ measured serum na

Clinical Laboratory Medicine (9 decks)

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