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S2B5 MEDI > Hyponatremia > Flashcards

Hyponatremia Flashcards

(51 cards)

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1
Q

hypovolemia

  • define
  • what causes it?
A
  • contraction of the EVF (extracellular fluid volume)
  • due to combined salt and water loss
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2
Q

what is hyponatremia and what causes it

A
  • a decrease in Na+ serum concentration
    • defined as serum [Na+] below 135 mEq/L
    • due to either loss of Na+ or or dilution of Na+ due to excessive body water
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3
Q

what serum [Na+] constites mild, moderate and severe hyponatremia

A
  • Mild :130-134 mEq/L - often asymptomatic
  • Moderate: 120-129 mEq/L
  • Severe: <120 mEq/L
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4
Q

at what serum [Na] might neurological symptoms present?

A

115 mEq/L

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5
Q

various symptomatology seen in hyponatremia

A
  1. Mild or absent symptoms
  2. Moderately severe symptoms:
  • Nausea without vomiting
  • Confusion
  • Headache
  1. Severe symptoms:
  • Vomiting
  • Cardiorespiratory arrest
  • Seizures
  • Reduced consciousness/ coma
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6
Q

major causes of hyponatremia

A
  • vomitting, diarrhea: fluid and Na+ loss
  • diuretics: fluid and Na+ loss
  • inadequate salt intake
  • gastrointestinal suckling
  • mannitol:
    • dilution hyponatremia
    • a shift of fluid from teh ICF to the ECF due to hypertonicity in the ECF dilutes serum Na+ and lowers serum Na+ concentration
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7
Q

what is normal serum osmolality?

A

280-295 mosm/kg

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8
Q

how to calculate serum osmolality

A

2 [Na+] + [glucose]/18 + BUN/2.8

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9
Q

ADH

  • where is it synthesized
  • when it is released
  • what does it do
A
  • a hormone synthesized by the hypothalamus
  • stored in the pituitary and released in states of high serum osmolality
    • _​_acts on distal collecting tubule and collecting ducts to increase their permeability to water
    • is a vasoconstrictor
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10
Q

what compartments make hole the total body water?

how much volume does each contain?

A
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11
Q

what is hypoosmolality

A
  • serum osmolality less than 280 mOsm/Kg
  • indicates excess total body water relative to body solutes
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12
Q

IV infusions are administered into what fluid compartment?

A

into the insterstitium (component of ECV)

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13
Q

what is hypertonic hyponatremia?

what are examples?

A
  • hyponatremia due to overall hypertonicity ( > 290 mOsm) caused by a different solute in the extracellular space that draws water from the ICV into the ECV, thus diluting soeium
    • hyperglycemia - high serum glucose
    • hypertonic infusions (these are administered into the interstitial space, cause a hypertonic ECV)
      • glucose infusion
      • mannitol infusion - given for cerebral edema
      • maltose - given alongside IgG administration
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14
Q

isotonic hyponatremia

  • define
  • what causes it?
A
  • hyponatremia seen when ECV osmolarity overall normal (270-290)
  • caused by:
  • psueodhyponatremia: fake lab error resulting from
    • ​hyperlipidemia
    • hyperproteinemia
  • gycine in TURP: isotonic glycine given in trans urethral prostate resection
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15
Q

hypotonic hyponatremia

A
  • hyponatremia in the context of low overall osmolarity (<270 Mosm) in the extracellular space
    • three types of hopotonic hyponatremia
      • hypovolemic
      • euvolemic
      • hypervolemic
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16
Q

hypovolemic hyponatremia

  • describe the fluid/solute status of the extracellular space
  • what are causes of this state?
A
  • this is a type of hypotonic hyponatremia ( <270 mosm)
  • due to a loss of both total body water and total body sodium but a proportionally LARGER loss of sodium
  • causes:
    • GI losses:
      • vomitting
      • diarrhea
      • blood loss
    • Renal loss:
      • diruetics
      • adrenal insufficiency: Na+ wasting
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17
Q

define euvolemic hyponatremia

A

a type of hypotonic hyponatremia where

  • TBW has increased
  • total salt is normal
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18
Q

what pathological states can cause euvolemic hyponatremia?

A
  • SIADH: syndrome of innapropriate ADH secretion
  • psychogenic polydispia

both lead to elevated total body water in the context of normal total body salt

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19
Q

define hypervolemic hyponatremia

A

a type of hypotonic hypontremia where

  • BOTH TBW and total body Na+ increase
    • relatively LARGER increase in TBW with respect to total body Na+
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20
Q

what pathological states can lead to hypervolemic hyponatremia?

A
  • states that decrease extracellular circulating blood volume (ECBV)
    • ​these states all lead to edema (either due to impaired fluid return to heart or low plasma oncotic pressure) ​
      • CHF: weak heart function
      • ​cirrhoris: low sythesis of plasma proteins
      • nephrotic syndrome: innapropriate filtration of plasma proteins, leading to low serum plasma proteins
    • renal railure (acute or chornic)
  • low ECVB leads to –> increased Na+ and water retentention –> hypervolemia
    • more water retention relative to sodium retention
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21
Q

what clinical presentations to look for in possible hypovlemia?

Study These Flashcards
A

 Examination of skin and mucous membranes

 Low BP

 Postural hypotension

 Increased capillary refill

22
Q

what clinical presentations to look for in possible hypervolemia?

Study These Flashcards
A

 JVD

 Edema

23
Q

what is the use of urine sodium concentration in the assesment of hyponatremia?

Study These Flashcards
A

urine sodium concentration can be used to distinguish between hypovolemia (decreased by TBW and TBNa+, bigger drop in TBNa+) and euvolemia (increased TBW, normal TBNa+)

24
Q

what specific history should you estbalish with a hyponatremic patients?

Study These Flashcards
A

determine if they had recent surgery and involving administration of:

  • large volumes hypotonic fluid
    • ex: prostate or intrauterine procedures)
  • large volume of hypertonic IV fluid
    • mannitol, glycerol, IVIg
  • they were treated with lipemic serum
25
what are the three main labs you should order for the diagnosis of hyponatremia?
* serum osmolality (normal: 270-290 mOsm) * urine osmolality * urine sodium concentration
26
what does urine osmolarity \> 100 mOsm/kg indicate?
indicates in impaired ability of the kidney _to dilute_ the urine. * urine is therefore too concentrated * usually secondary to **increased ADH**
27
other than the main labs, what labs to get for diagnosis of hyponatremia?
 TSH/ FT4- to rule out hypothyroidsm  Uric acid: _Low in SIADH_  Cortisol- to rule out Adrenal insufficiency  Lipids/albumin
28
uric acid levels can be used to rule in what type of hyponatremia?
uric acid levels will be _low_ in SIADH (type of euvolemic hyponatremia)
29
what type of imaging to get in patients with _suspected SIADH_ or suspected _cerebral salt wasting_ ?
had CT scan and chest radiography
30
based on plasma osmolality, volume status, and urine sodium, outline the diagnosis of the different subsets of hyponatremia
31
SIADH * define * list its causes * what type of hyponatremia does ADH cause * how to diagnose
* inappropriate ADH secretion * excess water reaborption limits the ability of the kidney to dilute urine * leads to a **euvolemic hypotonic hyponatremia** * causes: * neoplasms * pneumonia * menigitis * drugs: * SSRIs * NSAIDS * carbamazepine * chemotherapy (cilastin) * diagnosis: * main labs * low serum osmarility: * \< 270 mOsm (confirms hyponatremia) * **check urine osmolalitity!** * _high serum osmolarity:_ * **_​_\> 100 mOsm/kg** * _high urine [na+]_ * _​_\> ​**20 mEq/L** * other labs: * REDUCED URIC ACID\*
32
discuss cardio, renal and hepatic function in SIADH
Normal renal, hepatic and cardiac function
33
psychogenic polydypsia * define * what type of hyponatremia does it lead * how to diagnose
* caused by excessive intake of water * this increases total body water and leads to _severly diluted urine_ * **euvolemic hypotonic hyponatremia** * diagnosis: * serum osmolarity low (\< 270 mOsm) * _check urine osmolality:_ * low urine osmolaritity * \< 100 mOsm/kg * \< 20 mEq/L
34
exercise associated hyponatremia - what is the serum/urine osmolarity who is at risk? what is the treatment?
* _excessive water intake_ seen in the context of marathons & other endurance events * anyone who has prolonged exercise who is drinking lots of fluids is at risk * urine osmolarity * **low ( \< 100 mOSm)** * urine is dilute * treatment: * if pt is _asymptomatic:_ **water restriction** * if pt is _symptomatic:_ **give hypertonic saline**
35
beer potomia
* excessive beer consumption * beer has low solute/water ratio * causes a hypotonic hyponatremia * low urine osmolarity (\< 100 mOsm/kg) like in EAH * can also lead to malnutrition
36
define acute, subuacte and chronic hypotranemia
 Acute (\< 24 hours)  Subacute (\>24-48)  Chronic (\>48hrs)
37
define mild, moderate and severe hyponatremia
 Mild: 130-134 mEq/L  Mod: 120-129 mEq/L  Severe\<120 mEq/L
38
hyponatremia treatment goals
* to oprevent further decline in the Na+ concentration * to relieve symptoms of hyponatremia
39
excessive correction of hyponatremia can lead to what disease?
osmotic demylination syndrome
40
describe the presentation of ODS (osmotic demylination syndrome)
 Paresis  Dysphagia  Dysarthria  Diplopia  Loss of consciousness  Ataxia  Parkinsonism
41
what are the fluid replacement options for hyponatremia?
* normal saline * lactated ringers * hypertonic saline * reserved for patients with **moderate-severe hyponatremia** (\< 129 mEq/L)
42
acute hyponatremia * what defines "acute" * what is the goal of treatment * what are the limitations of treatment
* acute: presented \< 48 hrs ago * goal is to raise **[Na+] by 4-6 mmol** * **​**takes about 6-8 hrs to correct, then _maintain_ for 24 hrs * blood [Na+] _not to_ increase by more than 12 mEq in 24 hrs
43
chronic hyponatremia * treatment goals * what adjustments should be made regading risk of ODS?
* chronic hyponatremia: \> 48 hours * goal: raise [Na+] by **4-8 mmol/L** in **24 hours** * accounting for ODS: * _low risk for ODS:_ * max correction of hyponatremia by an increase of _10-12 mmol/L_ in 24 hr period (or 18 mmol/L in 48 hr period) * _high risk for ODS:_ * max correction of of hyponatremia by an increase of _8 mmol/L_ in 24 hrs * **possible high ODS risk pts:** * pt with [Na+] \< 105 mEq/L * hypokalemic pts * malnourished pts * alcoholic/liver diseases pts
44
treatment of hypovolemic hyponatremic patients?:
* administer **isotonic/hypertonic saline** * hypovolemia secondary to _diuretic use_ **may also need K+ repletion**
45
how to treat euvolemic hyponatremia patients that _are_
asymptomatic * f_ree water restriction_ (\<1/day) * treat SIADH, psychogenic polydispia, EAH this way
46
treatment for hypervolemic hyponatremic patients:
* give Na+ while _restricting fluid_ * vasopressin (receptor) antagonists * if CHD: * add loop diuretics and an ACE/ARB
47
how to treat hyponatremic patients that are _overtly symptomatic_ - i.e., have s**eizures/severe neurological deficits**
**administer 3% hypertonic saline**
48
furosemide - what kind of drug? - indications for use? - how it is given? - MOA and effects? - when it is possibly contradindicated/when should it be used with caution?
* indications: **hypervolemic hypontramia** * **​**_given with saline_ * loop diuretic * MOA: acts on the thin ascending loop of henle, on the NKCC (Na+/K+/2Cl-) transporter * decreases Na+ reabsorption (as well as Cl, Mg++, Ca++, mildly K+), i_ncreasing free water excretion_ * use with caution in **hypokalemic patients**, since it can lead to K+ secretion in the collecting ducts
49
demeclocycline * what kind of drug is it * indications * MOA
* a tetracycline antiobiotic * MOA: binds 30s subunit inhibiting protein synthesis * causes diuresis * indication: in conjunction with _fluid restriction_, be used to treat SIADH
50
tolvaptan * what kind of drug/MOA/effects * what are is uses * contraindications/cautions
* uses: **hypervolemic** or **euvolemic** hyponatremia * is a vasopressin (ADH) antagonist * MOA: binds vasopressin receptor V2, inhibiting ADH binding * effects: * increases urine output * decrease urine osmlality (dilutes urine) * normalizes serium sodiu mlevels * cautions: * do NOT use over 30 days or you risk liver injury * if given to patients in a **hospital:** the hospital _MUST have serum Na+ monitoring_ * contraindicaitons: liver disease
51
covinaptan what kind of drug/MOA/effects uses
* a ADH(vasopressin) antagonists * blocks V2 and V1a receptors * MOA/effects are same as tolvaptan * increased urine ouput * decreased urine osmolality (dilute urine) * indication: **euvolemic a**nd **hypervolemic** hyponatremia in **_patients that are hospitalized_** * **_​_**given IV

S2B5 MEDI (7 decks)

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