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Unit 2 Clin Med Lab > L4: Sodium disorders > Flashcards

L4: Sodium disorders Flashcards

1
Q

Total body water=

A

60% of total body weight

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2
Q

Female total body water=

A

50%

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3
Q

Infant total body water=

A

80%

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4
Q

Elderly total body water=

A

45%

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5
Q

Male total body water=

A

60%

ofc bc everything is set to men

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6
Q

Overweight total body water=

A

smaller %

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7
Q

ICF total body water=

A

40%

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8
Q

ECF total body water=

A

20%

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9
Q

ECF=

A

plasma + interstitial fluid

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10
Q

Extracellular ions:

A

primarily Na+, Cl-

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11
Q

Intracellular ions:

A

primarily K+, Po4-

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12
Q

ECF osmolarity=

A

sodium + glucose + urea

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13
Q

ICF osmolarity=

A

potassium + magnesium + phosphate + proteins

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14
Q

normal osmolarity

A

280-295 mOsm/kg

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15
Q

calculated osmolarity

A

2Na+ + Glucose/18 + BUN/2.8

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16
Q

symptoms occur when osmolarity is out of range:

A

<265

>320

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17
Q

Osmolal gap due to osmotically active substances not accounted for in calculated osmolarity _________. Normal is ____

A

mannitol, ethanol, methanol, ethylene glycol

Normal <10

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18
Q

Tonicity

A

The ability of the combined effect of all the solutes to generate an osmotic driving force

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19
Q

To generate tonicity

A

the solutes must be confined in one comparment

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20
Q

Urea is an example of a substance which contributes to ______

A

osmolarity

does not contribute to tonicity because it crosses cell membranes

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21
Q

decreasing ECF tonicity by decreasing sodium would cause

A

water to move into cells, swelling

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22
Q

major determinant of the size of the extracellular fluid volume

A

Na+

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23
Q

increased ECF Na+ would cause

A

hypervolemia

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24
Q

decreased ECF Na+ would cause

A

hypovolemia

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25
Q

serum sodium refers to

A

Refers to the amount of water relative to the Na+ in the ECF

NOT the total body Na+ amount

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26
Q

abnormal serum Na+ is a sign of

A

disorder of water regulation

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27
Q

ECFV is determined by

A

overall volume status of the patient

sodium control

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28
Q

abnormal ECFV is a sign of

A

abnormal sodium control

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29
Q

Sequestration without loss:

A

intestinal obstruction, pancreatitis, rhabdomyolysis

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30
Q

renal cause of H20 and Na+ loss

A

Diuretic

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31
Q

renal cause of water loss

A

Diabetes Insipidus

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32
Q

Oliguria means

A

producing little urine

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33
Q

CNS depression, weakness, muscle cramps occur with

A

hypovolemia

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34
Q

reasson why an otherwise healthy patient might be hypervolemic

A

Pregnancy

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35
Q

bolded causes of hypervolemia

A

Liver disease

Heart failure

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36
Q

Orthopnea, paroxysmal nocturnal dyspnea (PND), SOB, and crackles are pulmonary symptoms of

A

hypervolemia

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37
Q

influence water retention

A

Thirst

ADH

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38
Q

influence salt retention

A

Renin angiotensin system**
ANP
catecholamines,
renal: GFR, RBF

39
Q

ADH definition

A

produced in hypothalamus, transported to posterior pituitary then released into blood stream
Causes retention of water but normal excretion of Na+

40
Q

Aldosterone causes

A
  1. increases sodium reabsorption

2. Increases K+ excretion

41
Q

Most common electrolyte abnormality in hospitalized patients

A

hyponatremia

42
Q

Hyponatremia is defined as serum sodium

A

Hypotonic, Na+ <135, dangerous if <125

43
Q

hyponatremia presentation

A

Very young/very old

HA, dizziness, N/V, lethargy, weakness, confusion, hypoventilation→ respiratory arrest, seizures, coma, death

44
Q

seizures are common in

A

hyponatremia

45
Q

hyponatremia causes fluid to move

A

into cells, symptoms result from movement into brain cells–> cerebral edema

46
Q

after realizing sodium levels are out of range, next determine

A

patient’s volume status: hypovolemic, euvolemic, hypervolemic

47
Q

hyponatremia is associated with which disorders?

A

Pulmonary disease

CNS disorders

48
Q

pseudohyponatremia is seen with

A

Hyperlipidemia
Hyperproteinemia
Obstructive jaundice
Multiple myeloma

49
Q

pseudohyponatremia definition

A

Na+ <135 but isoosmolar
Falsely low serum sodium: laboratory artifact
→ relative percent of water is reduced and flame photometry reports artificially low sodium→ do specialized tests

50
Q

Redestributive hyponatremia aka

A

Hyperosmolar hyponatremia

51
Q

Hyperosmolar hyponatremia cause

A

Hyperglycemia:

Add 1.5 mEq/L to sodium value for every 100 mg/dl of serum glucose greater than baseline (100 mg/dl)

52
Q

Redestributive hyponatremia definition

A

Hyperosmolar state, “relative hyponatremia”

Caused by osmotically active solutes in extracellular space that draw H2O out of the cell into the extracellular space

53
Q

True hyponatremia is

A

hypo-osmolar hyponatremia

54
Q

causes of hypovolemic hyponatremia

A

Renal losses:
Diuretics, esp thiazide
Osmotic diuresis: glucose/mannitol
Addison’s disease: decreased cortisol → increased ADH

Non-renal losses:
GI: V/D, NG suction, fistula, pancreatitis, peritonitis
Burns

55
Q

causes of hypervolemic hyponatremia

A 
Hepatic cirrhosis
Congestive Heart Failure
Renal failure
Nephrotic syndrome
Pregnancy
56
Q

treatment of hypervolemic hyponatremia

A

Diuretics
Dialysis
Fluid restriction

57
Q

treatment of hypovolemic hyponatremia

A

Replace fluid losses with isotonic fluid

treat underlying cause

58
Q

Causes of euvolemic hyponatremia

A

SIADH
Psychogenic polydipsia→ urine is maximally dilute
Hypothyroidism
Adrenal insufficiency

59
Q

Euvolemic Hyponatremia treatment

A

Fluid restriction

Treat underlying cause

60
Q

SIADH cause

A

Impairs free water excretion, but sodium continues to be excreted normally

61
Q

Causes of SIADH

A

hospitalization
medications
CNS disorder (do CT/MRI of head)
lung tumor/infection (check CXR)

62
Q

SIADH labs

A

Concentrated urine >100mOsm/kg with low serum osmolality and euvolemia

63
Q

SIADH treatment

A 
Fluid restriction
Treat underlying pathology
Refractory cases: 
Hypertonic saline
Demeclocycline
Urea
Lithium
Vaptan
64
Q

when to hospitalize hyponatremic patient

A

if <125

65
Q

slowly correct chronic hyponatremia or else

A

risk of Cerebral pontine myelinolysis/osmotic demyelination syndrome

66
Q

meds for chronic hyponatremia

A

Demeclocycline

Vaptans

67
Q

Vaptans

A

vasopressin receptor antagonists

68
Q

Demeclocycline

A

induces nephrogenic diabetes insipidus

69
Q

when to treat chronic hyponatremia with Hypertonic solutions 3% NaCl

A

severe, symptomatic cases

70
Q

rate of correction for severe symptomatic hyponatremia

A

6-12 mEqL, <18 mEq/L in 48 hours
Chronic: <8 mEq/L 1st 24 hours

Check serum sodium every 2 hours

71
Q

osmotic demyelination syndrome aka

A

central pontine myelinolysis

72
Q

central pontine myelinolysis

A

irreversible focal demyelination in the pons and extra-pontine areas

73
Q

central pontine myelinolysis symptoms

A

Dysarthria, dysphagia, seizures, AMS, quadriparesis, hypotension 1-3 days after sodium overcorrection

74
Q

hypernatremia is defined as

A

Hypertonic, Na+ >145 mEq/L

75
Q

hypernatremia pathophysiology

A

→ increased ECF osmolality → water leaves cells → brain shrinkage → clinical features

76
Q

general causes of hypernatremia

A

too little water intake
very high dietary salt
excessive water loss

77
Q

specific general causes of hypernatremia

A

elderly/infant diarrhea
Sweating/fever
Renal losses
Drugs: diuretics, lithium (induces nephrogenic diabetes insipidus)
Osmotic diuresis: hyperglycemia, mannitol

78
Q

lithium MOA

A

induces nephrogenic diabetes insipidus

79
Q

hypernatremia symptoms

A 
Asymptomatic
Thirst, volume depletion
AMS, weakness
Neuromuscular irritability
Focal neurologic deficit
Seizures, coma
80
Q

most hypernatremia is due to

A

water loss

81
Q

normal mechanisms to respond to hypernatremia

A
  1. thirst

2. concentrate urine to prevent further water loss

82
Q

central diabetes insipidus causes

A

head injury

83
Q

nephrogenic diabetes insipidus causes

A

Genetic

Acquired:
chronic renal insufficiency
tubulointerstitial renal disease
Amyloidosis
Lithium
84
Q

Diabetes insipidus definition

A

Nonosmotic urinary water loss with elevated serum sodium: urine is dilute when it should be concentrated, water is not reabsorbed in collecting duct

Central/Neurogenic: impaired secretion of ADH
Nephrogenic: lack of kidney response to ADH

85
Q

Treatment of central diabetes insipidus

A

desmopressin: IV/inhaled ADH analog

86
Q

Treatment of nephrogenic diabetes insipidus

A

Thiazide diuretic
Amiloride
Chlorpropamide
indomethacin

87
Q

Amiloride

A

potassium sparing diuretic

88
Q

indomethacin

A

NSAIDS

89
Q

Chlorpropamide

A

antidiabetic oral agent

90
Q

hypernatremia tx

A

Hospitalize if severe
Stop water loss
Replace water deficit SLOWLY (esp if chronic):
Orally, NG tube, IV hypotonic fluid

91
Q

If water is replaced too rapidly in hypernatremia

A

water into brain cells → seizures, brain damage, cerebral pontine myelinolysis

92
Q

water deficit=

A

normal TBW-current TBW

93
Q

Normal TBW=

A

.6 x body weight in kg

94
Q

Current TBW=

A

Normal serum Na+ x normal TBW / measured serum Na+

Unit 2 Clin Med Lab (8 decks)

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