L4: Sodium disorders Flashcards
(94 cards)
1
Q
Total body water=
A
60% of total body weight
2
Q
Female total body water=
A
50%
3
Q
Infant total body water=
A
80%
4
Q
Elderly total body water=
A
45%
5
Q
Male total body water=
A
60%
ofc bc everything is set to men
6
Q
Overweight total body water=
A
smaller %
7
Q
ICF total body water=
A
40%
8
Q
ECF total body water=
A
20%
9
Q
ECF=
A
plasma + interstitial fluid
10
Q
Extracellular ions:
A
primarily Na+, Cl-
11
Q
Intracellular ions:
A
primarily K+, Po4-
12
Q
ECF osmolarity=
A
sodium + glucose + urea
13
Q
ICF osmolarity=
A
potassium + magnesium + phosphate + proteins
14
Q
normal osmolarity
A
280-295 mOsm/kg
15
Q
calculated osmolarity
A
2Na+ + Glucose/18 + BUN/2.8
16
Q
symptoms occur when osmolarity is out of range:
A
<265
>320
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
18
Q
Tonicity
A
The ability of the combined effect of all the solutes to generate an osmotic driving force
19
Q
To generate tonicity
A
the solutes must be confined in one comparment
20
Q
Urea is an example of a substance which contributes to ______
A
osmolarity
does not contribute to tonicity because it crosses cell membranes
21
Q
decreasing ECF tonicity by decreasing sodium would cause
A
water to move into cells, swelling
22
Q
major determinant of the size of the extracellular fluid volume
A
Na+
23
Q
increased ECF Na+ would cause
A
hypervolemia
24
Q
decreased ECF Na+ would cause
A
hypovolemia
25
serum sodium refers to
Refers to the amount of water relative to the Na+ in the ECF
| *NOT the total body Na+ amount*
26
abnormal serum Na+ is a sign of
disorder of water regulation
27
ECFV is determined by
overall volume status of the patient
| sodium control
28
abnormal ECFV is a sign of
abnormal sodium control
29
Sequestration without loss:
intestinal obstruction, pancreatitis, rhabdomyolysis
30
renal cause of H20 and Na+ loss
Diuretic
31
renal cause of water loss
Diabetes Insipidus
32
Oliguria means
producing little urine
33
CNS depression, weakness, muscle cramps occur with
hypovolemia
34
reasson why an otherwise healthy patient might be hypervolemic
Pregnancy
35
bolded causes of hypervolemia
Liver disease
| Heart failure
36
Orthopnea, paroxysmal nocturnal dyspnea (PND), SOB, and crackles are pulmonary symptoms of
hypervolemia
37
influence water retention
Thirst
| ADH
38
influence salt retention
Renin angiotensin system**
ANP
catecholamines,
renal: GFR, RBF
39
ADH definition
produced in hypothalamus, transported to posterior pituitary then released into blood stream
Causes retention of water but normal excretion of Na+
40
Aldosterone causes
2. increases sodium reabsorption
| 2. Increases K+ excretion
41
Most common electrolyte abnormality in hospitalized patients
hyponatremia
42
Hyponatremia is defined as serum sodium
Hypotonic, Na+ <135, dangerous if <125
43
hyponatremia presentation
Very young/very old
| HA, dizziness, N/V, lethargy, weakness, confusion, hypoventilation→ respiratory arrest, seizures, coma, death
44
seizures are common in
hyponatremia
45
hyponatremia causes fluid to move
into cells, symptoms result from movement into brain cells--> cerebral edema
46
after realizing sodium levels are out of range, next determine
patient's volume status: hypovolemic, euvolemic, hypervolemic
47
hyponatremia is associated with which disorders?
Pulmonary disease
| CNS disorders
48
pseudohyponatremia is seen with
Hyperlipidemia
Hyperproteinemia
Obstructive jaundice
Multiple myeloma
49
pseudohyponatremia definition
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
Redestributive hyponatremia aka
Hyperosmolar hyponatremia
51
Hyperosmolar hyponatremia cause
Hyperglycemia:
| Add 1.5 mEq/L to sodium value for every 100 mg/dl of serum glucose greater than baseline (100 mg/dl)
52
Redestributive hyponatremia definition
Hyperosmolar state, “relative hyponatremia”
| Caused by osmotically active solutes in extracellular space that draw H2O out of the cell into the extracellular space
53
True hyponatremia is
hypo-osmolar hyponatremia
54
causes of hypovolemic hyponatremia
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
causes of hypervolemic hyponatremia
```
Hepatic cirrhosis
Congestive Heart Failure
Renal failure
Nephrotic syndrome
Pregnancy
```
56
treatment of hypervolemic hyponatremia
Diuretics
Dialysis
Fluid restriction
57
treatment of hypovolemic hyponatremia
Replace fluid losses with isotonic fluid
| treat underlying cause
58
Causes of euvolemic hyponatremia
SIADH
Psychogenic polydipsia→ urine is maximally dilute
Hypothyroidism
Adrenal insufficiency
59
Euvolemic Hyponatremia treatment
Fluid restriction
| Treat underlying cause
60
SIADH cause
Impairs free water excretion, but sodium continues to be excreted normally
61
Causes of SIADH
hospitalization
medications
CNS disorder (do CT/MRI of head)
lung tumor/infection (check CXR)
62
SIADH labs
Concentrated urine >100mOsm/kg with low serum osmolality and euvolemia
63
SIADH treatment
```
Fluid restriction
Treat underlying pathology
Refractory cases:
Hypertonic saline
Demeclocycline
Urea
Lithium
Vaptan
```
64
when to hospitalize hyponatremic patient
if <125
65
slowly correct chronic hyponatremia or else
risk of Cerebral pontine myelinolysis/osmotic demyelination syndrome
66
meds for chronic hyponatremia
Demeclocycline
| Vaptans
67
Vaptans
vasopressin receptor antagonists
68
Demeclocycline
induces nephrogenic diabetes insipidus
69
when to treat chronic hyponatremia with Hypertonic solutions 3% NaCl
severe, symptomatic cases
70
rate of correction for severe symptomatic hyponatremia
6-12 mEqL, <18 mEq/L in 48 hours
Chronic: <8 mEq/L 1st 24 hours
Check serum sodium every 2 hours
71
osmotic demyelination syndrome aka
central pontine myelinolysis
72
central pontine myelinolysis
irreversible focal demyelination in the pons and extra-pontine areas
73
central pontine myelinolysis symptoms
Dysarthria, dysphagia, seizures, AMS, quadriparesis, hypotension 1-3 days after sodium overcorrection
74
hypernatremia is defined as
Hypertonic, Na+ >145 mEq/L
75
hypernatremia pathophysiology
→ increased ECF osmolality → water leaves cells → brain shrinkage → clinical features
76
general causes of hypernatremia
too little water intake
very high dietary salt
excessive water loss
77
specific general causes of hypernatremia
elderly/infant diarrhea
Sweating/fever
Renal losses
Drugs: diuretics, lithium (induces nephrogenic diabetes insipidus)
Osmotic diuresis: hyperglycemia, mannitol
78
lithium MOA
induces nephrogenic diabetes insipidus
79
hypernatremia symptoms
```
Asymptomatic
Thirst, volume depletion
AMS, weakness
Neuromuscular irritability
Focal neurologic deficit
Seizures, coma
```
80
most hypernatremia is due to
water loss
81
normal mechanisms to respond to hypernatremia
1. thirst
| 2. concentrate urine to prevent further water loss
82
central diabetes insipidus causes
head injury
83
nephrogenic diabetes insipidus causes
Genetic
```
Acquired:
chronic renal insufficiency
tubulointerstitial renal disease
Amyloidosis
Lithium
```
84
Diabetes insipidus definition
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
Treatment of central diabetes insipidus
desmopressin: IV/inhaled ADH analog
86
Treatment of nephrogenic diabetes insipidus
Thiazide diuretic
Amiloride
Chlorpropamide
indomethacin
87
Amiloride
potassium sparing diuretic
88
indomethacin
NSAIDS
89
Chlorpropamide
antidiabetic oral agent
90
hypernatremia tx
Hospitalize if severe
Stop water loss
Replace water deficit SLOWLY (esp if chronic):
Orally, NG tube, IV hypotonic fluid
91
If water is replaced too rapidly in hypernatremia
water into brain cells → seizures, brain damage, cerebral pontine myelinolysis
92
water deficit=
normal TBW-current TBW
93
Normal TBW=
.6 x body weight in kg
94
Current TBW=
Normal serum Na+ x normal TBW / measured serum Na+
