Sodium and Water Disorders Flashcards
1
Q
Normal adults are considered to have a minimal obligatory water intake of ________ mL/ day
A
1600 mL/day
2
Q
what is the breakdown of water needs per day
A
Ingested water- 500mL
Water in food- 800mL
Water from oxidation – 300mL
3
Q
what is the normal water loss per day
A
2.5-3 Liters per 24 hours
4
Q
what is the breakdown of water losses
A
Loss from urine 500mL
Skin- 500mL
Respiratory Tract- 400mL
Stool- 200mL
5
Q
what conditions require increased fluid needs
A
burns, diarrhea, dehydration, fever
6
Q
what conditions require decreased fluid needs
A
CHF, renal failure, iatrogenic fluid overload, mechanical ventilation
7
Q
where does most of the water go?
A
intracellular fluid
8
Q
what is determined by the concentrations of effective osmoles in the ECF.
A
tonicity
9
Q
_________ osmoles are solutes that can not move freely across cell membranes.
A
Effective
10
Q
what is the main effective osmole in the ECF?
A
Sodium
11
Q
when there is decreased wall stress in the atria and pulmonary vasculature the hypothalamus is stimulated to release what? This is the low pressure system
A
ADH
12
Q
what stimulated the reinin-angiotensin-aldosterone system
A
Baroreceptors in aortic arch, carotid sinus, and juxtaglomerular apparatus
(high pressure system)
13
Q
________ cleaves angiotensin to generate Angiotensin I
A
Renin
14
Q
Angiotensin I is then cleaved by _______________ to Angiotensin II
A
angiotensin converting enzyme (ACE)
15
Q
what does angiotensin II lead to
A
Stimulation of Aldosterone secretion by adrenal gland
Increased reabsorption of NaCl from proximal tubule
Central stimulation of thirst and secretion of ADH
Arteriolar vasoconstriction
16
Q
What solutions are hypotonic
A
D5W
1/2 NS
17
Q
what is an isotonic solution
A
Normal Saline
lactated ringers
18
Q
what is a hypertonic solution
A
3% saline
19
Q
is dextrose a good volume replacement
A
no, good for patients who need calories
20
Q
where does dextrose distribute?
A
to all compartment
21
Q
what types of saline are hypotonic? where are they distributed
A
1/4 NS and 1/2 NS
distributed to intracellular (mainly), plasma, interstitial
22
Q
where is 0.9% NS (isotonic) distributed
A
ECF only
23
Q
problem w/ 0.9% NS in large volumes
A
acidosis
24
Q
when is 0.9% NS useful
A
dehydration/ hypovolemic state
25
Is 3% saline commonly used?
No, hypertonic and high solute in extracellular compartment draws water from intracellular compartment
26
More physiologic isotonic solution than NS
| Confined to extracellular compartment
Lactated Ringers
27
Is NS or lactated ringers safer in large volumes
Lactated ringers
28
when is a fluid imbalance desirable?
correction for dehydration
| fluid overload in CHF patients
29
what is the major determinant of ECF osmolality?
Sodium
30
what 2 other things contribute to ECF osmolality?
chloride
| bicarbonate
31
what is the normal range for serum sodium
135-145 mEq/L
32
do serum sodium concentrations always reflect total body sodium concentrations
No
33
If a patient is hypernatremic what must you look at next?
volume status (Hypervolemia, isovolemic, hypovolemic)
34
If a patient is hyponatremic, what must you assess next?
Tonicity
| can be hypertonic, isotonic, hypotonic (3 different fluid levels)
35
what antiepileptic can cause SiADH?
carbamazepine
36
what antiepileptic can cause diabetes insipidus?
phenytoin
37
a count of the number of particles in a fluid sample
osmolality
38
what regulates osmolality
ADH
39
ADH is also secreted in response to hypovolaemia and this stimulus will over-ride any response to _________________ .
serum osmolality
40
what is the normal range of urine osmolality
50-1200 mmol/kg
41
what is the best measure of urine concentration
urine osmolality
42
The main factor determining urine concentration is the amount of water which is resorbed in ______ and ________ in response to ADH.
the distal tubules and collecting ducts
43
In a dehydrated patient with normally functioning pituitary and kidneys, a small volume of highly _____________ urine will be produced.
concentrated
44
when is serum osmolality used?
investigation of hyponatraemia and identificaiton of an osmolar gap
45
when does hypernatremia usually occur?
hospitalized patients (elderly and breastfed infants more common)
46
what is the serum level of Na in hypernatremia?
Na > 145 mEq/L
| always associated w/ hypertonicity- serum > 295 mOsm
47
IF a person is hypernatremic what do you classify them according to?
ECF status
48
what can lead to hypervolemic hypernatremia?
Sodium overload
sodium bicarb therapy
albumin therapy
mineralcorticoid excess
49
what can cause isovolemic hypernatremia?
diabetes insipidus
osmotic diuretic
hyperglycemia
no access to water
50
what can cause hypovolemic hypernatremia (losing both water and Na but losing water to greater extend than sodium)
```
renal disorders
diuretics
diarrhea
laxative abuse
excess sweating
```
51
what is a Disorder of antidiuretic hormone (ADH) release that causes isovolemic hypernatremia.
diabetes insipidus
52
what are the 2 types of diabetes insipidus
central
| nephrogenic
53
what is the clinical presentation of diabetes insipidus?
dehydration
volume depletion
increase in urine output
54
causes of central DI?
CNS tumors
cerebral clots of bleed
head trauma
TB, syyphilis
55
what are nephrogenic causes of DI?
renal diseases
56
what drugs can induce DI?
lithium, phenytoin, foscarnet, demeclocycline
57
what can decrease in brain volume in DI cause?
Decrease in brain volume can cause rupture of cerebral vein, hemorrhages, and irreversible neurological damage
58
symptoms of DI?
lethargy, weakness, confusion, restlessness, irritability
59
what would a patient w/ hypervolemic hypernatremia look like?
edematous
| pulmonary congestion
60
how do you treat hypervolemic hypernatremia?
need to dilute sodium and remove excess sodium and fluid
administer a hypotonic solution (D5W)
and add a loop diuretic (furosemide)
61
what can happen if serum Na is decreased too quickly
cerebral edema, seizures, permanent neurological damage
62
how do you treat isovolemic hypernatremia?
replace water deficit
give D5W at 1.3-2 mL/kg/hour
ADH (vasopressin) analgoue/ DDAVP
adjunct- HCTZ, carbamazepine, chlorpropamide
63
how do you treat nephrogenic diabetes insipidus
thiazide diuretic and dietary sodium restriction
64
what is the problem w/ hypovolemic hypernatremia
losing more fluid than Na, but losing both of them
65
Tx for hypovolemic hypernatremia
restore intravascular volume w/ NS
replace free water deficit
can switch to more hypotonic solution once fluid is replaced
66
what is hyponatremia
Serum sodium < 135 mEq/L
67
what is the most common electrolyte abnoramlity in hospitalized patients?
hyponatremia
68
do all patient w/ hyponatermia need Na?
No
69
what can cause high plasma osmolaity hyponatremia?
hyperglycemia
| Mannitol
70
What can cause normal plasma osmolality hyponatremia?
hyperproteinemia
hyperlipidemia
bladder irrigation
71
what can cause low plasma osmolality hyponatremia
figure out if urine is dilute, it yes then primary polydipsia, recent osmostat
If urine isn't dilute need to access fluid status
72
If a patient is hyponatremic w/ hypertonic what is usually the cause?
excess osmols in ECF (including serum)
| usually caused by excess glucose
73
how do you treat hyponatremic w/ isotonic fluid
tx underlying cause of hyperproteinemia
hyperlipidemia
bladder irrigation
74
have excess water in relation to existing fluid stores.
hypotonic hyponatremia
75
have excess total body Na with excess of ECF
hypervolemic hypotonic hyponatremia
76
causes of hypervolemic hypotonic hyponatremia
CHF
cirrhosis
hypoalbuminemia
77
patient has normal total body Na, but there is a small increase in ECF.
isovolemic hyptonic hyponatermia
78
causes of isovolemic hyptonic hyponatermia
```
imbalance of ins and out
SIADH
excessive ADH activity (SSRI, Ecstasy)
defective renal diluting mechanism
altered thirst
psychiatric disorder
```
79
Release of ADH when not needed or increased response to ADH
| opposite of diabetes insipidus
SiADH
80
what are non-drug causes of SiADH?
CNS tumors, cerebral thrombosis or bleed, head trauma
| meningitis, pneumonias, TB
81
What can cause drug induced SiADH
NSAIds, carbamazepine, vincristine
opioids, phenobarbital, thiazide diuretics
TCAs, ecstasy
82
what is due to a loss of sodium and ECF, but more Na
Hypovolemic Hypotonic Hyponatremia
83
causes of Hypovolemic Hypotonic Hyponatremia
GI losses (V/D)
renal lsoses (diuretic)
weating
iatrogenic
84
for Hypovolemic Hypotonic Hyponatremia if loss of sodium is from an extrarenal cause, the urine sodium concentration will be ____?
low (<20mEq/L)
85
for Hypovolemic Hypotonic Hyponatremia if loss of sodium is from an renal cause, the urine sodium concentration will be ____?
high (>20 mEq/L)
86
if Na is <120 mEq/L what can happen??
Seizures
coma
death
87
is serious and can develop one to several days after aggressive treatment of hyponatremia by any method, including water restriction alone. Shrinkage of the brain triggers demyelination of pontine and extrapontine neurons that can cause neurologic dysfunction, including quadriplegia, pseudobulbar palsy, seizures, coma, and even death.
osmotic demyelination
88
what increase the risk of the complication of osmotic demyelination?
Hepatic failure, potassium depletion, and malnutrition
89
what is Hypervolemic Hypotonic Hyponatremia Treatment
restrict salt and water
restrict fluids to 1 to 1.2 L/day
restrict dietary sotium to 1-2 grams per day
may need to administer loop diuretics to remove water
may consider hypertonic saline if rapid onset (<48 hours)
90
Hypovolemic Hypotonic Hyponatremia Treatment
replace sodium and volume loss w/ NS
don't correctly too quickly (avoid demyelination)
if rapid onset can use 3% saline infusion
91
Tx for Severe Euvolemic Hypotonic Hyponatremia
Hypertonic saline
fluid restriction
loop diuretic
92
Isovolemic Hypotonic Hyponatremia Treatment
need to correct cause (hypothyroidism, glucocorticoid deficiency)
induce negative water bounce (want outs to exceed ins)
fluid restrict to 1 to 1.2 L/day
93
Isovolemic Hypotonic Hyponatremia – Treatment of SiADH
treat underlyign cause
restrict fluid intake
may need hypertonic saline
94
pharmacotherapy for SiADH
demeclocycline (abx) (inhibits ADH)
lithium (stops ADH at collecting tubules)
phenytoin (inhibit ADH release)
95
Severe Euvolemic Hypotonic Hyponatremia Treatment
Hypertonic saline
Fluid restriction
Loop diuretic
