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Renal > Hypernatremia > Flashcards

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
Q

What kind of hypernatremia can cause brain shrinakge, cerebral blood vessel tears, limbic demyelination, eABV elevation and acute pulmonary edema?

A

hypertonic sodium gain

26
Q

Who is most likely to have hypodipsia?

A

elderly adults who are infirm, with diminished thirst and no access to water

27
Q

Are most liquid losses in the body hypotonic or hypertonic? what does this mean for SNa?

A

hypotonic - they cause hypernatremia through free water loss

28
Q

What is the only kind of liquid loss in the body that is isotonic?

A

secretory diarrhea

29
Q

Persistent inhibition of ADH is: central or nephrogenic diabetes insipidus?

A

central

30
Q

tubular unresponsiveness to ADH is: central or nephrogenic diabetes insipidus?

A

nephrogenic

31
Q

As urine flow rate increases,w hat happens to pure water diuresis?

A

the urine osmolarity will drop because there is less time to remove solutes

32
Q

As urine flow rate increases, what happens to solute diuresis?

A

it increases, because osmolarity increases as flow rate increases

33
Q

As urine flow rate increases, are urine losses relatively water rich or poor?

A

rich - causes hypernatremia by leaving residual TBW hypertonic

34
Q

Why is hypokalemia common in hyperglycemic polyuria?

A

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
Q

When can primary polydipsia be excluded in the water deprivation test?

A

when Sna > 145 mEQ/L and/or Uosm > Posm

36
Q

What does the water deprivation test in the setting of polyuria help us differentiate between?

A

central and nephrogenic diabetes insipidus, polydipsia

37
Q

Why do you measure UV, Uosm, weight, SNa, and Posm repeatedly during the water deprivation test?

A

to see when the patient reaches steady state

38
Q

When do you stop the water deprivation test and administer desmopressin?

A

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
Q

When do you give desmopressin in the water deprivation test?

A

When Uosm is stable for 2 or 3 hours despite rising Posm , or Posm is > 295 or SNa > 145

40
Q

If the response to desmopressin is a Uosm that rises > 100%, what is the diagnosis?

A

central diabetes insipidus

41
Q

If the response to desmopressin is a Uosm that rises 15-50% (> 300 mOsm), what is the dix?

A

partial central diabetes insipidus

42
Q

If the response to desmopressin is no change to Uosm, what is the dx?

A

nephrogenic diabetes insipidus

43
Q

If the response to desmopressin is a small rise in Uosm (< 300 mOsm), what is the dx?

A

partial nephrogenic diabetes insipidus

44
Q

How should acute Na intoxicatin with neurologic symptoms be treated?

A

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
Q

How do you estimate target water deficit in hypernatremia?

A

current TBW x (SNa/140 - 1)

46
Q

What is TBW in men?

A

0.6 lean body weight

47
Q

What is TBW in women?

A

0.5 lean body weight

48
Q

what is TBW in the elderly?

A

0.45 lean body weight

49
Q

How should SNa be corrected with high serum glucose?

A

SNa + (glucose - 100/100) x 2)

50
Q

How should hypernatremia caused by sweating , GI losses or solute diuresis be treated?

A

0.9 saline or 0.45 saline + potassium

51
Q

How can you calculate rate of fall SNa from a 1L infusion?

A

(infused Na + infused K) - SNa/TBW + 1L

52
Q

HOw do you treat acute central DI?

A

with 2 mcg desmopressin IV x 12 hours

53
Q

How is nephrogenic DI treated?

A

low Na/low protein diet
thiazide diuretics
NSAIDs

54
Q

HOw is x linked V2r treated (experimentally)?

A

vaptans

55
Q

What are normal insensible water loss for a 70 kg person?

A

500 ml/day/m2 or 800 ml/day

56
Q

How should IV infusions be given in treating hypernatremia?

A

water and sodium infusions should be separate

Renal (28 decks)

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