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Renal 2 > Dysnatremias > Flashcards

Dysnatremias Flashcards

1
Q

What is hypernatremia?

A

Sodium over 145

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2
Q

What are the 2 main phases of hypernatremia?

A

Generation and maintenance

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3
Q

What are 2 forms of generation phase of hypernatremia?

A
  1. Loss of later
  2. Gain of salt (sodium ingestion via salt tabls and infant formula, mineralocorticoid excess, and iatrogenic via IV fluids, dialysis, tube feeds, and TPN)
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4
Q

What are 2 forms of the maintenance phase of hypernatremia?

A
  1. Failure to drink water

2. Inability to sense thirst

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5
Q

Are hyper and hypo natremia issues with salt?

A

NO they are issues with water

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6
Q

General view of hypernatremia?

A

Loss of water leading to dehydration

-If patient can take in H20 normally, it shoudl correct itself

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7
Q

What is hypernatremia most often caused by?

A

A loss of water either renal or extra renal

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8
Q

What are 2 renal causes for loss of water leading to hypernatremia?

A
  1. Diabetes insipidus

2. Osmotic diuresis

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9
Q

What are the 2 types of diabetes insipidus?

A
  1. Central

2. Nephrogenic

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10
Q

Describe central DI?

A

Inability of brain to release ADH

  • Caused by brain injury (iatrogenic (surgery), trauma, tumors, ischemic insults, infections)
  • Kidneys are normal
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11
Q

Does central DI respond to ADH when supplied?

A

YES

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12
Q

Describe nephrogenic DI?

A

Inability of kidney to respond to ADH

  • The collecting tubules are impermeable to water (can be caused by chronic lithium use, congenital, or demeclocycline)
  • Other causes of poor response to ADH include hypercalcemia, loop diuretics, hypokalemia, sickle cell
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13
Q

What is the 1st step to diagnosing DI?

A

Water restriction test…this differentiates psychogenic polydipsia, CDI, and NDA

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14
Q

In the water restriction test, what is seen if the patient has hyponatremia due to psychogenic polydipsia?

A

There is a progressive increase in the urine osmolarity

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15
Q

What is seen in the water restriction test if the patient has NDI or CDI?

A

NOTHING…no change in urine osmolarity

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16
Q

What will happen if you give ADH to someone with CDI?

A

THe urine osmolarity will increase

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17
Q

What will happen if you give ADH to someone with NDI?

A

No change in urine osmolarity

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18
Q

What will happen if you give ADH to someone with psychogenic polydipsia?

A

No change in urine osmolarity

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19
Q

What is the treatment for psychogenic polydipsia?

A

STOP DRINKING

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20
Q

What is the treatment for CDI?

A

DDAVP (desmopressin)

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21
Q

What is the treatment for NDI?

A

Diuretics…thiazide with K-sparing will increase water resorption in ADH independent regions of the kidney

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22
Q

What are 3 causes of osmotic diuresis?

A
  1. Hyperglycemia
  2. Post-obstructive (can’t void… like in BPH)
  3. Mannitol: Diuretic that makes you pee a lot… have to keep up with fluid intake
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23
Q

Generally, what is happening in osmotic diuresis?

A

You are peeing out lots of water and become hypernatremia (you need to drink H20)…

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24
Q

What are 3 sources of extra renal loss of water?

A
  1. Skin losses: Burns
  2. Pulmonary Losses: Advanced COPD, breating too fast/too often
  3. GI losses: Acute diarrhea, IBD
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25
Q

What are signs and symptoms of hypernatremia?

A

Confusion, lethargy, weakness, seizure, coma

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26
Q

What is the risk in treating hypernatremia?

A

The speed of correction

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27
Q

What is the speed of correction in chronic (over 48 hours) asymptomatic hypernatrmia?

A

Don’t excees 0.5mEq/L/hr

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28
Q

What is the speed of correction in acute (less than 48 hours) symptomatic hypernatremia?

A

1-1.15 mEq/L/hr until symptoms improve, then slow the rate to 0.5mEw/L/hr

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29
Q

Why do we recheck Na levels frequently when correcting them?

A

Want to avoid an undesirable rate

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30
Q

What is the rate at which we should give fluids?

A

Deficit/time

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31
Q

How to we calculate time to correction?

A

Difference between current and normal sodium/ 0.5

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32
Q

How do we calculate water deficit?

A

Estimated TBW * Weight in Kg * (Current Na/140-1)

Estimated TBW is 0.5 in males and 0.4 in females

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33
Q

What is hyponatermia?

A

Plama sodium under 135

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34
Q

What is typically the problem in hyponatremia?

A

WATER (ingested water is greater than excreted water)

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35
Q

What things can result in too much water with normal intake?

A
  1. Renal failure (dialysis helps with this)

2. Increased ADH (lung tumors, heart failure, cirrhosis)

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36
Q

Can excessive intake of water overwhelm normal kidneys leading to hyponatremia?

A

YES

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37
Q

What are the marks of true hyponatremia?

A

Low plasma osmolarity and low plasma Na

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38
Q

What 2 states are considered to be pseudohyponatremia?

A

Normal plasma osmolarity and low plasma Na

High plama osmolarity and low plasma Na

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39
Q

What conditions are associated with pseudohyponatremia with normal plasma osmolarity?

A
  1. Hyperlipidemia

2. Hyperproteinemia

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40
Q

What conditions are associated with pseudohyponatremia with high plasma osmolairty?

A
  1. Glucose (hyperglecemia dilutes down NA)

2. Mannitol

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41
Q

If ADH is present, is the urine osmolality high?

A

YES

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42
Q

If there is ADH present, what do you need to do?

A

Determine if it is appropriate or inappropriate

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43
Q

What are states where presence of ADH is appropriate with hyponatremia?

A
  1. Hypervolemia (CHF, nephrosis, cirrhosis)

2. Hypovolemia (fluid losses)

44
Q

What are states where prescence of ADH is inappropriate?

A

Euvolemia: This can indicate SIAHD, hypothyroid, adrenal insufficiency

45
Q

Can you test urine osmality if the patient is on diuretics?

A

NO…you need to take these levels after 24 hours off of diuretics because diuretics can affect urine osmolality

46
Q

What needs to be done to determine a true hyponatremia (low serum Na and osmolality)?

A

You have to confirm the low level by checking the plasma osmolality (don’t use an estimated value)

47
Q

Once a true hyponatremia is established, what do you do next?

A

Assess volume status: Hypovolemic, euvolemic, hypervolemic

48
Q

What are signs of fluid overload (hypervolemic)?

A

Skin turgor, putting edema, JVD

49
Q

If your patient is hypovolemic or euvolemic, what do you do next?

A

Urine sodium and osmolality

50
Q

What is present if urine osmolality if high?

A

ADH

51
Q

What is seen in psychogenic polydipsia?

A

Low urine sodium and low urine osmolality

52
Q

What is seen in hypovolemic hyponatremia?

A

Low urine sodium and high urine osmolality (if not on diuretics) …associated with ADH

53
Q

What is seen in euvolemic hyponatremia?

A

High urine sodium and high osmolality (seen with SIADH, adrenal insufficiency, hypothyroidism)

54
Q

What are signs and symptoms of hyponatremia?

A

Seizure, nausea, headache, lethargy, confusion, coma

55
Q

What is predictive of symptoms in hyponatremia?

A

How quickly the level has changed (absolute level of hyponatremia isn’t always predictive of symptoms)

56
Q

What is acute hyponatremia?

A

Under 48 hours

57
Q

What is chronic hyponatremia?

A

Over 48 hours (true timeline isn’t usually known and is therefore chronic

58
Q

What is the most feared treatment complication in hyponatremia?

A

Central pontine myelinolysis

59
Q

When is central pontine myelinolysis seen?

A

With overly rapid correction of chronic compensated hyponatremia

60
Q

What is seen in central pontine myelinolysis?

A

Devastating neurologic consequences that typically lead to death within a matter of weeks

  1. Flaccid quadriplegia
  2. Respiratory muscle paralysis
  3. Coma
  4. Pseudobulbar palsy
61
Q

What are risk factors for central pontine myelinolysis?

A
  1. Over correction
  2. Improvement at a rate greater than 1-2mEq/hr
  3. EtOH
  4. Female
  5. Liver disease
  6. Malnutrition
62
Q

What is happening in central pontine meylinolysis to cause symptoms?

A

Rapid movement of fluid out of brain cells causing the cells to shrink and their myelin sheaths to crack (demyelinate from that)

63
Q

What can be done to see lesions in central pontine myelinolysis and when can you do this?

A

Lesions detectable on MRI and CT…may not be seen for up to 4 weeks

64
Q

How should you approach treatment of hyponatremia?

A

WITH CAUTION - Repeat levels in a couple of hours to be safe

65
Q

What’s the approach for treatment of hypovolemic hyponatremia?

A

0.9% saline, not difficult to correct

66
Q

What are symptoms due to in hypovolemic hyponatremia?

A

Volume depletion, not hyponatremia

67
Q

What else is 0.9% saline given for besides hypovolemic hyponatremia?

A

Hypotension, vomiting, diarrhea

68
Q

What is given for the acute treatment of euvolemic hyponatremia?

A
  • 3% saline for acute symptoms, but discontinue once severe symptoms resolve and sodium is in the safe range (100-125)
  • Water/fluid restriction (1000mL fluid a day)
  • Recheck sodium frequently
69
Q

What makes euvolemic hyponatremia worse in acute treatment?

A
  1. 9% saline

- You need to give fluid that is more concentrated than the urine osmolality

70
Q

What is given for chronic treatment of euvolemic hyponatremia (possibly from SIADH)?

A

This one is difficult to treat and maintain

  • Treat underlying disorder (like CA, which cna produce ADH like material)
  • Limit fluids
  • Demeclocycline (SE is hypernatremia because this dilutes urine even more)
  • Salt (or urea) tablets
71
Q

What is given for treatment of hypervolemic hyponatremia (perhaps from cirrhosis, nephrosis, or CHF)

A
  1. Treat underlying disorder (Maybe with ACEi or BB)
  2. Fluid restriction
  3. Diuretics
  4. Vasopressin receptor antagonists (aquaretic…which is electrolyte-free diuresis)
72
Q

What can happen from too much TPN?

A

Patient can become protein overfed, which will increase water output resulting in volume depletion and dehydration leading to iatrogenic hypernatremia

73
Q

If your patient is getting mannitol to control intracranial pressure, what can you see?

A

Pseudohypernatremia due to mannitol (ostmotic diuretic…peeing out all fluid)

74
Q

If you have a patient with polyuria and polydipsia with insatiable thirst what might be the cause of hyponatremia?

A

Hyperglycemia (DIABETIC) which is causing a pseudohyponatremia (glucose is diluting out all the Na)

75
Q

What’s a general guideline for how quickly hyponatrmia should be corrected?

A

10mEq/L/day

76
Q

If you correct hyponatremia too quickly, what can happen?

A

Osmotic demyelination syndrome

77
Q

Who is at risk for osmotic demyelination syndrome?

A
  1. Lower starting sodium (110 or lower)
  2. Advanced liver disease
  3. Alcoholism
  4. Chronic hyponatremia: 48-72 hours or if previous Na unknown
  5. Corrected from hyponatremia too quickly (more than 10-12mEw/L in a 24 hour period
78
Q

What indicates that a patient will begin to correct from hyponatremia too quickly?

A

Polyuria (so measure their urine output hourly)

79
Q

How often should serum Na be checked

A

Every 3-4 hours

80
Q

What can you do if the Na begins to rise at an undesirable rate?

A
  1. Hypotonic fluids can be ordered (D5 which will decrease Na back to safe rate of correction)
  2. DDAVP can be given (vasopressin will drop urine flow
81
Q

In psychogenic polydipsia, what is a common feature of the urine?

A

It has a low urine sodium and low urine osmolality

82
Q

In psychogenic polydipsia what should you do regarding water and liquids

A

Restrict them! Even guard the toilet

83
Q

If you have a patient who has stopped drinking and presents with normal BP and hypernatremia, what will you give?

A

IV D5W at 100mL/hr and recheck sodium every 4 hours

84
Q

If you have a patient who has stopped drinking and presents hypotensive with hypernatrmia, what will you give?

A

IV 0.9% saline at 250ml/hr

-This is given to normalize the BP, then any volume depletion (still hypernatrmic) can be treated with D5W

85
Q

If you have a patient who is dehydrated and can drink lots of water, can they correct their own hypernatrmia?

A

YES

86
Q

What will 0.225% saline cause?

A

RBC lysis… it’s too hypotonic…don’t use this fluid

87
Q

How do you differentiate between dehydration and volume depletion?

A
  • Dehydration requires a high sodium

- Volume depletion can have a normal Na

88
Q

What do you treat dehydration with?

A

WATER (because they have high sodium)

89
Q

What do you treat volume depletion with?

A

SALT (like an isotonic fluid or something)

90
Q

How do you calculate how many fluids to give?

A

Dosing factor * weight * (Serum Na/140-1)

Dosing factor is 0.6 is male and 0.5 is female

91
Q

If a patient has hypernatremia and is given desmopressin with no change in urine output (decrease), what might he have?

A

Nephrogenic DI because it isn’t responding to desmopressin

92
Q

What can cause NDI?

A

Chronic lithium use

93
Q

What can be given for someone with hypernatremia due to NDI?

A

D5W

94
Q

If patient has hypernatremia and it responds to desmopressin (via fall in urine output), what might she have?

A

Central diabetes insipidus

95
Q

In someone with CDI, what will the urine osmolality be before and after treatment?

A

Before it will be DILUTE, after it will be CONCENTRATED

96
Q

What types of sitations might result in CDI

A

Maybe a brain surgery or something affecting the BRAIN

97
Q

If someone has lung cancer, what else are you thinking they might have?

A

SIADH

98
Q

What clinical features are seen in someone with SIADH (possibly from a lung tumor)?

A

Hyponatremia (reataining water), low BUN and uric acid, super concetrated urine (high urine osmolality and sodium)

99
Q

If the BUN is high, what does that indicate?

A

Volume depletion

100
Q

If BUN is low, what does that indicate?

A

Mild volume overload

101
Q

If someone with lung cancer is hyponatremic, but their urine sodium and urine osmolality are normal to low, what might be the reason?

A

They could be puking their guts out from chemo (NOT ALL LUNG CA PATIENTS HAVE SIADH)

102
Q

What kind of urine osmolality number are you looking at in someone with SIADH?

A

Over 300 or at least more than serum osmolality

103
Q

If you’re giving someone in labor oxytoxin and them a crap ton of fluids and they become hyponatremic, what could be the cause?

A

Oxytocin causes you to secrete ADH, so then she can’t excrete all that extra water you are giving her and she will become hyponatremic and SEIZE

104
Q

Why would a little old thin lady on hydrochlorothiazide become hyponatremic?

A

Since she’s peeing so much from the diuretic, she might think she needs to drink more to compensate, so she drinks a ton of water and becomes hyponatremic

105
Q

So if your old lady on thiazide diuretics has hyponatrmia, what are you gonna do about it?

A
  • Start her on 0.9% saline and check her in 4 hours
  • If correcting too fast, can give 3% saline
  • NO excess water drinking or fluids with this
106
Q

When is a time you might see hypernatremia in a kid?

A

When their parents are messed up and give the salt tablets in Munchhausen by proxy

Renal 2 (10 decks)

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