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Hypernatremia Flashcards

1
Q

Is ADH release more sensitive to small increases in tonicity or EABV?

A

plasma tonicity

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2
Q

is ADH release more sensitive to LARGE increases in tonicity or EABV?

A

EABV

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3
Q

As tonicity increases and EABV decreases, how does ADH sensitivity change?

A

increases

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4
Q

What is the SNa cutoff for hypertonic hypernatremia?

A

145 mEq/L

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5
Q

When do most adults begin showing symptoms of hypernatremia?

A

SNa > 160 mEq/L

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6
Q

What are symptoms of hypernatremia?

A

seizures, coma, somnolence, lethargy, thirst

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7
Q

When is aggressive treatment for hypernatremia started?

A

when SNa is above 155 mEq/L , regardless of symptoms

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8
Q

What is the rapid adaptation to hypernatremia in the brain?

A

Swelling by accumulating electrolytes, increasing osmolality

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9
Q

What is the slow adaptation of hypernatremia in the brain?

A

accumulation of organic osmolytes

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10
Q

How fast should SNa fall when treating hypernatremia, so as to avoid cerebral edema?

A

< 8 mEq/L/day

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11
Q

Does isotonic volume depletion or hypertonicity cause cellular dehydration?

A

hypertonicity

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12
Q

Can dehydration by itself produce recognizable volume depletion? Why?

A

No - water is lost from ECF in smaller amounts compared to hypertonic dehydration, which loses greater amounts from BOTH ICF and ECF - this is much more likely to cause a very elevated SNa

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13
Q

In the absence of ADH, what happens to water diuresis in the setting of volume depletion or decreased renal solute?

A

it’s impaired

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14
Q

How can you develop hypertonic hypernatremia? (2)

A

intake of hypertonic salt OR persistent water loss without replacement

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15
Q

What do you always know about the patient if they have persistent hypertonic hypernatremia?

A

they either have absent thirst or they cannot access water in their living situation

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16
Q

Who is most likely to be hypertonic/hypernatremic?

A

elderly, infirm, infants, and intubated

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17
Q

What are the 3 classes of hypertonic hypernatremia?

A

hypertonic Na Gain
polyuric
non polyuric

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18
Q

what are the 2 kinds of polyuric hypernatremias?

A

solute diuresis and pure water diuresis

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19
Q

what are the two types of pure water diuresis polyuric hypernatremias?

A

central and nephrogenic diabetes insipidus

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20
Q

Drinking sea water, hypertonic feeding, hypertonic enemas, 3% saline, Bicarb infusion, and primary aldosteronism are all examples of what kind of hypernatremia?

A

hypertonic sodium gain

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21
Q

elevated glucose, mannitol, urea, diuretics, NaCl and bicarb are examples of what cause for hypernatremia?

A

solute diuresis leading to polyuria

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22
Q

What are some causes of central diabetes insipidus?

A 
alcohol 
pituitary tumors 
post brain surgery 
trauma 
cysts
 granulomatosis 
pregnancy 
meningoencephalitis 
genetic mutations in ADH
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23
Q

What are some causes of nephrogenic diabetes insipidus?

A 
hypercalcemia 
hypokalemia 
renal disease 
drugs 
genetic mutations in V2R and AQP2
24
Q

hypodipsia, fever, sweating, vomiting, diarrhea and cathartics all cause what class of hypernatremias?

A

non polyuric - no intake and therefore no replacement for free water clearance/loss

25
What kind of hypernatremia can cause brain shrinakge, cerebral blood vessel tears, limbic demyelination, eABV elevation and acute pulmonary edema?
hypertonic sodium gain
26
Who is most likely to have hypodipsia?
elderly adults who are infirm, with diminished thirst and no access to water
27
Are most liquid losses in the body hypotonic or hypertonic? what does this mean for SNa?
hypotonic - they cause hypernatremia through free water loss
28
What is the only kind of liquid loss in the body that is isotonic?
secretory diarrhea
29
Persistent inhibition of ADH is: central or nephrogenic diabetes insipidus?
central
30
tubular unresponsiveness to ADH is: central or nephrogenic diabetes insipidus?
nephrogenic
31
As urine flow rate increases,w hat happens to pure water diuresis?
the urine osmolarity will drop because there is less time to remove solutes
32
As urine flow rate increases, what happens to solute diuresis?
it increases, because osmolarity increases as flow rate increases
33
As urine flow rate increases, are urine losses relatively water rich or poor?
rich - causes hypernatremia by leaving residual TBW hypertonic
34
Why is hypokalemia common in hyperglycemic polyuria?
tubular flow rate and solute load have increased, washing out solute gradient. Meanwhile, ENac takes up sodium, which produces a relative electronegativity near the CCD
35
When can primary polydipsia be excluded in the water deprivation test?
when Sna > 145 mEQ/L and/or Uosm > Posm
36
What does the water deprivation test in the setting of polyuria help us differentiate between?
central and nephrogenic diabetes insipidus, polydipsia
37
Why do you measure UV, Uosm, weight, SNa, and Posm repeatedly during the water deprivation test?
to see when the patient reaches steady state
38
When do you stop the water deprivation test and administer desmopressin?
When 1. Uosm is > 600, 2. Uosm is stable for 2 or 3 hours despite rising Posm , or 3. Posm is > 295 or SNa > 145
39
When do you give desmopressin in the water deprivation test?
When Uosm is stable for 2 or 3 hours despite rising Posm , or Posm is > 295 or SNa > 145
40
If the response to desmopressin is a Uosm that rises > 100%, what is the diagnosis?
central diabetes insipidus
41
If the response to desmopressin is a Uosm that rises 15-50% (> 300 mOsm), what is the dix?
partial central diabetes insipidus
42
If the response to desmopressin is no change to Uosm, what is the dx?
nephrogenic diabetes insipidus
43
If the response to desmopressin is a small rise in Uosm (< 300 mOsm), what is the dx?
partial nephrogenic diabetes insipidus
44
How should acute Na intoxicatin with neurologic symptoms be treated?
D5W - if within 24 hours, then the goal is to correct SNa to 145 - if longer than 48 hours, SNa should not fall faster than 8 mEq/L/day
45
How do you estimate target water deficit in hypernatremia?
current TBW x (SNa/140 - 1)
46
What is TBW in men?
0.6 lean body weight
47
What is TBW in women?
0.5 lean body weight
48
what is TBW in the elderly?
0.45 lean body weight
49
How should SNa be corrected with high serum glucose?
SNa + (glucose - 100/100) x 2)
50
How should hypernatremia caused by sweating , GI losses or solute diuresis be treated?
0.9 saline or 0.45 saline + potassium
51
How can you calculate rate of fall SNa from a 1L infusion?
(infused Na + infused K) - SNa/TBW + 1L
52
HOw do you treat acute central DI?
with 2 mcg desmopressin IV x 12 hours
53
How is nephrogenic DI treated?
low Na/low protein diet thiazide diuretics NSAIDs
54
HOw is x linked V2r treated (experimentally)?
vaptans
55
What are normal insensible water loss for a 70 kg person?
500 ml/day/m2 or 800 ml/day
56
How should IV infusions be given in treating hypernatremia?
water and sodium infusions should be separate

Renal (28 decks)

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