Hyponatremia diagnostic study of choice: Difference between revisions

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== Overview ==
== Overview ==
    
    
Best diagnostic test to measure hyponatremia, serum sodium < 135 mEq/L, is direct ion-specific electrode potentiometry. Other tests are associated with false results in certain conditions.
Different etiologies of hyponatremia are differentiated based on serum osmolality, urine osmolality, and urine sodium.
To see the different caused of hyponatremia, click [[Hyponatremia causes#Causes|here]].


== Study of choice ==
== Study of choice ==
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  | author = [[F. S. Apple]], [[D. D. Koch]], [[S. Graves]] & [[J. H. Ladenson]]
  | author = [[F. S. Apple]], [[D. D. Koch]], [[S. Graves]] & [[J. H. Ladenson]]


  | title = Relationship between direct-potentiometric and flame-photometric measurement of sodium in blood
  | title = Relationship between the direct-potentiometric and flame-photometric measurement of sodium in the blood


  | journal = [[Clinical chemistry]]
  | journal = [[Clinical chemistry]]
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* Ion-specific electrode (ISE) potentiometry
* Ion-specific electrode (ISE) potentiometry
ISE potentiometry has two different subtypes: Direct (undiluted) and indirect (diluted). '''Direct ISE''' measures plasma sodium directly from a whole-blood sample and its not associated with either pseudohyponatremia or pseudonormonatremia.
ISE potentiometry has two different subtypes: Direct (undiluted) and indirect (diluted).  
 
'''Direct ISE''' measures plasma sodium directly from a whole-blood sample and it's not associated with either pseudohyponatremia or pseudonormonatremia.


FES or indirect ISE requires sample dilution before assay  <ref name="HussainAhmad20152">{{cite journal|last2=Ahmad|first2=Zahid|last3=Garg|first3=Abhimanyu|year=2015|title=Extreme hypercholesterolemia presenting with pseudohyponatremia - a case report and review of the literature|journal=Journal of Clinical Lipidology|volume=9|issue=2|pages=260–264|doi=10.1016/j.jacl.2014.11.007|issn=19332874|last1=Hussain|first1=Iram}}</ref> and both are associated with pseudohyponatremia.
FES or indirect ISE requires sample dilution before assay  <ref name="HussainAhmad20152">{{cite journal|last2=Ahmad|first2=Zahid|last3=Garg|first3=Abhimanyu|year=2015|title=Extreme hypercholesterolemia presenting with pseudohyponatremia - a case report and review of the literature|journal=Journal of Clinical Lipidology|volume=9|issue=2|pages=260–264|doi=10.1016/j.jacl.2014.11.007|issn=19332874|last1=Hussain|first1=Iram}}</ref> and both are associated with pseudohyponatremia.
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<br>
<br>
'''Biochemical evaluation for finding the etiologies of hyponatremia :'''
'''Biochemical evaluation for finding the etiologies of hyponatremia :'''
{{columns-list|2|
 
* Serum sodium
* Serum sodium
* Serum osmolality
* Serum osmolality
* Serum potassium
* [[Serum potassium]]
* Serum chloride
* Serum chloride
* Serum creatinine
* [[Serum creatinine]]
* Serum other solutes
* Serum other solutes
* Serum urea
* Serum [[urea]]
* Serum uric acid
* Blood Glucose
* Blood Glucose
* Total protein and albumin
* Total protein and albumin
* Serum lipids
* Serum [[lipids]]
* Total bilirubin and direct bilirubin
* Total bilirubin and direct bilirubin
* Red and white cell blood count
* Red and white cell blood count
* Serum cortisol
* Serum [[Cortisol level|cortisol]]
* Adrenocorticotropine hormone
* Adrenocorticotropine hormone
* ADH level
* [[ADH|ADH level]]
* TSH
* [[TSH]]
* Urine sodium
* Urine sodium
* Urine chloride
* Urine chloride
* Urine osmolality
* [[Urine osmolality]]
* Urine for other solutes
* Urine for other solutes
* Fraction excretion of sodium
* Fraction excretion of sodium
* Calculated GFR
* Calculated [[GFR]]
}}
 
<br>
<br>
For differential diagnosis click [[Hyponatremia differential diagnosis|here]].
For differential diagnosis click [[Hyponatremia differential diagnosis|here]].
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{{familytree | | | | | | | | A01 |A01=Serum sodium < 135 mEq/L}}  
{{familytree | | | | | | | | A01 |A01=Serum sodium < 135 mEq/L}}  
{{familytree | | | | | | | | |!| | | | | | | }}
{{familytree | | | | | | | | |!| | | | | | | }}
{{familytree | | | | | | | | A02 | | | | | |A02=<table><tr><th>Psuedohyponatremia</th></tr><tr><td> • Check for '''hyperglycemia'''<br>• Check for '''hyperproteinemia'''<br>• Check for '''hyperlipidemia'''<br>• Check for other '''solutes in serum'''<br>• Check for sign of '''Jaundice'''<br>• Check for history of '''operation'''</td></tr></table>}}
{{familytree | | | | | | | | A02 | | | | | |A02=<table><tr><th>Psuedohyponatremia</th></tr><tr><td> • Check for '''[[hyperglycemia]]'''<br>• Check for '''[[hyperproteinemia]]'''<br>• Check for '''[[hyperlipidemia]]'''<br>• Check for other '''solutes in serum'''<br>• Check for sign of '''[[Jaundice]]'''<br>• Check for history of '''operation'''</td></tr></table>}}
{{familytree | | | | | | | | |!| | | | | | | }}
{{familytree | | | | | | | | |!| | | | | | | }}
{{familytree | | | | | | | | B01 | | | | | |B01=Measure '''serum Osmolality'''}}
{{familytree | | | | | | | | B01 | | | | | |B01=Measure '''[[serum Osmolality]]'''}}
{{familytree | | | |,|-|-|-|-|^|-|-|-|-|.| | | }}
{{familytree | | | |,|-|-|-|-|^|-|-|-|-|.| | | }}
{{familytree | | | B01 | | | | | | | | B02 | | |B01='''Low < 280 momol/kg''' |B02='''Normal or High<br>> 280 momol/kg'''}}
{{familytree | | | B01 | | | | | | | | B02 | | |B01='''Low < 280 momol/kg''' |B02='''Normal or High<br>> 280 momol/kg'''}}
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{{familytree | | | C01 | | | | | | | | C02 |C01='''Hypotonic Hyponatremia'''|C02='''Isoosmolar or Hyperosmolar hyponatremia'''}}
{{familytree | | | C01 | | | | | | | | C02 |C01='''Hypotonic Hyponatremia'''|C02='''Isoosmolar or Hyperosmolar hyponatremia'''}}
{{familytree | | | |!| | | | | | | | | |!| }}
{{familytree | | | |!| | | | | | | | | |!| }}
{{familytree | | | D01 |-|-|-|.| | | | D03 |D01=<div style="text-align:left;border-left: 6px" > • Low GFR<br>• History of Thiazide use</div>|D03=• Post TURP or hysteroscopy (Glycine, Sorbitol)<br>• Direct sodium by direct potentiometry if normal measure total protein and lipid|boxstyle D01=text-align: left; | }}
{{familytree | | | D01 |-|-|-|.| | | | D03 |D01=<div style="text-align:left;border-left: 6px" > • Low GFR<br>• History of [[Thiazide]] use</div>|D03=• Post TURP or hysteroscopy (Glycine, Sorbitol)<br>• Check direct sodium by direct potentiometry if normal measure total protein and lipid|boxstyle D01=text-align: left; | }}
{{familytree | | | |!| | | | |!| | | | | | |}}
{{familytree | | | |!| | | | |!| | | | | | |}}
{{familytree | | | E01 | | | D02 |-| E02 |E01=No||D02=Yes|E02=• Renal failure<br>• Thiazide induce hyponatremia<br>}}  
{{familytree | | | E01 | | | D02 |-| E02 |E01=No||D02=Yes|E02=• [[Renal failure]]<br>• [[Thiazide]] induce hyponatremia<br>}}  
{{familytree | |,|-|^|-|-|-|.| | | | | | | | |}}
{{familytree | |,|-|^|-|-|-|.| | | | | | | | |}}
{{familytree | F01 | | | | F02 | | | | | | | |F01=Patients with '''edema'''<br>(pulmonary, peripheral), ascites|F02=Signs and Symptoms of '''hypovolemia'''<br>(↓ BP, Orthostatic hypotension)}}
{{familytree | F01 | | | | F02 | | | | | | | |F01=Patients with '''[[edema]]'''<br>(pulmonary, peripheral),[[ascites]]|F02=Signs and Symptoms of '''[[hypovolemia]]'''<br>(↓ BP, [[Orthostatic]] hypotension)}}
{{familytree | G01 | | | | |!| | | | | | | | |G01=Heart failure<br> Cirrhosis|}}
{{familytree | G01 | | | | |!| | | | | | | | |G01=[[Heart failure]]<br> [[Cirrhosis]]|}}
{{familytree | | | | | | | |!| | | | |,| G02 |G02=<table><tr><th>Less < 25 mEq/L<br>Hypovolemic Hyponatremia</th></tr><tr><td>• Extra renal loss<br>Gastrointestinal losses, Diuretics, Third space losses</td></tr></table>}}
{{familytree | | | | | | | |!| | | | |,| G02 |G02=<table><tr><th>Less < 25 mEq/L<br>Hypovolemic Hyponatremia</th></tr><tr><td>• Extra renal loss<br>Gastrointestinal losses, Diuretics, [[third sapcing of fluid|Third space losses]]</td></tr></table>}}
{{familytree | | | | | | | |!| | | | |!| |}}
{{familytree | | | | | | | |!| | | | |!| |}}
{{familytree | | | |,|-|-|-|^|-|-|.| |!| | |}}
{{familytree | | | |,|-|-|-|^|-|-|.| |!| | |}}
{{familytree | | | J01 | | | | | J02 |!| | | |J01=No|J02=Yes}}
{{familytree | | | J01 | | | | | J02 |!| | | |J01=No|J02=Yes}}
{{familytree | | | |!| | | | | | |!| |!| | | |}}
{{familytree | | | |!| | | | | | |!| |!| | | |}}
{{familytree | | | H01 | | | | | H02 |+| H03 | |H01=Measure '''urine sodium''' and '''serum osmolality'''|H02=Measure '''urine sodium'''|H03=<table><tr><th>25 to 40 mEq/L</th></tr><tr><td>• Infuse Isotonic saline 1 liter over 1 hour<br>• Remeasure urine sodium</td></tr></table>}}
{{familytree | | | H01 | | | | | H02 |+| H03 | |H01=Measure '''[[urine sodium]]''' and '''[[serum osmolality]]'''|H02=Measure '''[[urine sodium]]'''|H03=<table><tr><th>25 to 40 mEq/L</th></tr><tr><td>• Infuse Isotonic saline 1 liter over 1 hour<br>• Remeasure urine sodium</td></tr></table>}}
{{familytree | | | |!| | | | | | | | |!| | | |}}
{{familytree | | | |!| | | | | | | | |!| | | |}}
{{familytree | | | I01 |-|-|.| | | | |`| I03 |I01='''Urine <sub>Osm</sub> < 100'''|I03=<table><tr><th>Hight > 40 mEq/L<br>Hypovolemic Hyponatremia</th></tr><tr><td>• Renal loss</td></tr></table>}}
{{familytree | | | I01 |-|-|.| | | | |`| I03 |I01='''Urine <sub>Osm</sub> < 100'''|I03=<table><tr><th>Hight > 40 mEq/L<br>Hypovolemic Hyponatremia</th></tr><tr><td>• Renal loss</td></tr></table>}}
{{familytree | | | |!| | | I02 | | | | | |!| |I02=Yes|}}
{{familytree | | | |!| | | I02 | | | | | |!| |I02=Yes|}}
{{familytree | | | G01 | | G02 |-| G03 | |)| G04 |G01=No|G02='''Urine osmolality''' measured '''After therapy initiated'''|G03=Yes|G04=Use of diuretics}}
{{familytree | | | G01 | | G02 |-| G03 | |)| G04 |G01=No|G02='''[[Urine osmolality]]''' measured '''After therapy initiated'''|G03=Yes|G04=Use of diuretics}}
{{familytree | | | |!| | | |!| | | |!| | |!| |}}  
{{familytree | | | |!| | | |!| | | |!| | |!| |}}  
{{familytree | | | |!| | | |!| | | L03 | |)| L04 |L03=<table><tr><th>Recovery from one of the followings:</th></tr><tr><td>• Mild hypovolemia(Patients given isotonic fluids<br>• Hypopituitarism<br>(Patients given glucocorticoids))</td></tr></table>|L04='''Low cortisol,<br>Positive ACTH stimulation'''<br>Primary adrenal insufficiency}}
{{familytree | | | |!| | | |!| | | L03 | |)| L04 |L03=<table><tr><th>Recovery from one of the followings:</th></tr><tr><td>• Mild hypovolemia(Patients given isotonic fluids<br>• [[Hypopituitarism]]<br>(Patients given [[glucocorticoids]]))</td></tr></table>|L04='''Low [[cortisol]],<br>Positive [[ACTH]] stimulation'''<br>Primary [[adrenal insufficiency]]}}
{{Family tree| | | L01 | | L02 | | | | | |!| | | |L01='''Urine <sub>Na</sub> > 40 mEq/L'''|L02=No}}
{{Family tree| | | L01 | | L02 | | | | | |!| | | |L01='''Urine <sub>Na</sub> > 40 mEq/L'''|L02=No}}
{{familytree | |,|-|^|-|.| |!| | | | | | |`| P03 |P03='''Head injury/surgery'''<br>Cerebral-salt wasting}}
{{familytree | |,|-|^|-|.| |!| | | | | | |`| P03 |P03='''Head injury/surgery'''<br>[[Cerebral salt-wasting syndrome|Cerebral-salt wasting]]}}
{{familytree | P01 | | P02 |!| | | | | | | | | | |P01=No|P02=Yes}}
{{familytree | P01 | | P02 |!| | | | | | | | | | |P01=No|P02=Yes}}
{{familytree | |!| | | |!| |!| | | | | | | | | | }}
{{familytree | |!| | | |!| |!| | | | | | | | | | }}
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{{familytree | S01 | | |!| |`| R02 | | Q02 | | |R02=No|Q02=Yes|S01=Remeasure urine osmolality and sodium|}}
{{familytree | S01 | | |!| |`| R02 | | Q02 | | |R02=No|Q02=Yes|S01=Remeasure urine osmolality and sodium|}}
{{familytree | |!| | | |!| | | |!| | | |!| | | |}}
{{familytree | |!| | | |!| | | |!| | | |!| | | |}}
{{familytree | |!| | | |!| | | R03 | | Q03 | | |R03=<table><tr><th>High-fluid<br>low-protein diet including:</th></tr><tr><td>• Beer potomania<br>• Tea and toast diet</td></tr></table>|Q03=<table><tr><th>Water intoxication:</th><tr><tr><td>• Psychosis<br>• Endurance activity (Marathone)<br>• Ecstasy use</td></tr></table>}}
{{familytree | |!| | | |!| | | R03 | | Q03 | | |R03=<table><tr><th>High-fluid<br>low-protein diet including:</th></tr><tr><td>• [[Beer potomania]]<br>• Tea and toast diet</td></tr></table>|Q03=<table><tr><th>Water intoxication:</th><tr><tr><td>• [[Psychosis]]<br>• Endurance activity (Marathone)<br>• [[Ecstasy]] use</td></tr></table>}}
{{familytree | |)| Z02 |!| | | | | | | | | | | |Z02='''Urine <sub>Na</sub> >40 or<br>Urine <sub>Osm</sub> > 100'''}}
{{familytree | |)| Z02 |!| | | | | | | | | | | |Z02='''Urine <sub>Na</sub> >40 or<br>Urine <sub>Osm</sub> > 100'''}}
{{familytree | |!| |!| |!| | | | | | | | | | | |}}
{{familytree | |!| |!| |!| | | | | | | | | | | |}}
{{familytree | Z01 |!| |!| | | | | | | | | | | |Z01='''Urine <sub>Na</sub> < 40 or<br> Urine <sub>Osm</sub> < 100'''}}
{{familytree | Z01 |!| |!| | | | | | | | | | | |Z01='''Urine <sub>Na</sub> < 40 or<br> Urine <sub>Osm</sub> < 100'''}}
{{familytree | T01 |!| |!| | | | | | | | | | | |T01='''Hypovolemic Hyponatremia'''|}}
{{familytree | T01 |!| |!| | | | | | | | | | | |T01='''Hypovolemic Hyponatremia'''|}}
{{familytree | | | |`| T02 | | | | | | | | | | | |T02=<table><tr><th>Check for:</th></tr><tr><td>• Glucocorticoid deficiency with<br>Cortisol level and ACTH stimulationand <br>• Hypothyroidism with TSH</td></tr></table>}}
{{familytree | | | |`| T02 | | | | | | | | | | | |T02=<table><tr><th>Check for:</th></tr><tr><td>• Glucocorticoid deficiency with<br>[[Cortisol]] level and [[ACTH]] stimulationand <br>• [[Hypothyroidism]] with TSH</td></tr></table>}}
{{familytree | | | | | |!| | | | | | | | | | | |}}
{{familytree | | | | | |!| | | | | | | | | | | |}}
{{familytree | | | | | X01 | | | | | | | | | | |X01= check '''morning cortisol''' and<br>'''ACTH stimulation test'''}}
{{familytree | | | | | X01 | | | | | | | | | | |X01= check '''morning [[cortisol]]''' and<br>'''[[ACTH]] stimulation test'''}}
{{familytree | | | |,|-|^|-|.| | | | | | | |}}
{{familytree | | | |,|-|^|-|.| | | | | | | |}}
{{familytree | | | C01 | | C02 | | | | | | | |C01=Yes|C02=No}}
{{familytree | | | C01 | | C02 | | | | | | | |C01=Yes|C02=No}}
{{familytree | | | |!| | | |!| | |}}
{{familytree | | | |!| | | |!| | |}}
{{familytree | | | V01 | | V02 | | | |V01=Glucocorticoid deficiency|V02=Elevated '''TSH'''}}
{{familytree | | | V01 | | V02 | | | |V01=Glucocorticoid deficiency|V02=Elevated '''[[TSH]]'''}}
{{familytree | | | | | |,|-|^|-|-|.| | | | |}}
{{familytree | | | | | |,|-|^|-|-|.| | | | |}}
{{familytree | | | | | B01 | | | B02 | | | | | |B01=No|B02=Yes}}
{{familytree | | | | | B01 | | | B02 | | | | | |B01=No|B02=Yes}}
{{familytree | | | | | |!| | | | |!| | | | | | |}}
{{familytree | | | | | |!| | | | |!| | | | | | |}}
{{familytree | | | | | N01 | | | N02 | | | | | |N01=SIAD<br>Nephrogenic SIAD<br>Reset Osmostat|N02=Severe Hypothyroidism}}
{{familytree | | | | | N01 | | | N02 | | | | | |N01=SIAD<br>Nephrogenic [[SIADH|SIAD]]<br>Reset [[Osmostat]]|N02=Severe [[Hypothyroidism]]}}
{{familytree | | | | | |!| | | | | | | | | | |}}
{{familytree | | | | | |!| | | | | | | | | | |}}
{{familytree | | | | | M01 | | | | | | | | | |M01=Evaluate underlying [[Hyponatremia causes#Causes|etiology]]}}
{{familytree | | | | | M01 | | | | | | | | | |M01=Evaluate underlying [[Hyponatremia causes#Causes|etiology]]}}
{{familytree/end}}
{{familytree/end}}
</small>
</small>


==References==
==References==

Latest revision as of 20:31, 2 July 2021

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Saeedeh Kowsarnia M.D.[2]

Overview

Best diagnostic test to measure hyponatremia, serum sodium < 135 mEq/L, is direct ion-specific electrode potentiometry. Other tests are associated with false results in certain conditions.

Different etiologies of hyponatremia are differentiated based on serum osmolality, urine osmolality, and urine sodium.

To see the different caused of hyponatremia, click here.

Study of choice

Previously, there were two methods to determine serum sodium [1]   :

  • Flame emission spectrophotometry
  • Ion-specific electrode (ISE) potentiometry

ISE potentiometry has two different subtypes: Direct (undiluted) and indirect (diluted).

Direct ISE measures plasma sodium directly from a whole-blood sample and it's not associated with either pseudohyponatremia or pseudonormonatremia.

FES or indirect ISE requires sample dilution before assay [2] and both are associated with pseudohyponatremia.

Sequence of Diagnostic Studies

The most diagnostic studies which can help to diagnose and differentiate between different causes of hyponatremia are: Serum osmolality, urine osmolality, urine sodium.


Biochemical evaluation for finding the etiologies of hyponatremia :

  • Serum sodium
  • Serum osmolality
  • Serum potassium
  • Serum chloride
  • Serum creatinine
  • Serum other solutes
  • Serum urea
  • Blood Glucose
  • Total protein and albumin
  • Serum lipids
  • Total bilirubin and direct bilirubin
  • Red and white cell blood count
  • Serum cortisol
  • Adrenocorticotropine hormone
  • ADH level
  • TSH
  • Urine sodium
  • Urine chloride
  • Urine osmolality
  • Urine for other solutes
  • Fraction excretion of sodium
  • Calculated GFR


For differential diagnosis click here.

Diagnostic Approach to Hyponatremia [3] [4] [5]

 
 
 
 
 
 
 
Serum sodium < 135 mEq/L
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Psuedohyponatremia
• Check for hyperglycemia
• Check for hyperproteinemia
• Check for hyperlipidemia
• Check for other solutes in serum
• Check for sign of Jaundice
• Check for history of operation
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Measure serum Osmolality
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Low < 280 momol/kg
 
 
 
 
 
 
 
Normal or High
> 280 momol/kg
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hypotonic Hyponatremia
 
 
 
 
 
 
 
Isoosmolar or Hyperosmolar hyponatremia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
• Low GFR
• History of Thiazide use
 
 
 
 
 
 
 
 
• Post TURP or hysteroscopy (Glycine, Sorbitol)
• Check direct sodium by direct potentiometry if normal measure total protein and lipid
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
No
 
 
Yes
 
Renal failure
Thiazide induce hyponatremia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Patients with edema
(pulmonary, peripheral),ascites
 
 
 
Signs and Symptoms of hypovolemia
(↓ BP, Orthostatic hypotension)
 
 
 
 
 
 
 
Heart failure
Cirrhosis
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Less < 25 mEq/L
Hypovolemic Hyponatremia
• Extra renal loss
Gastrointestinal losses, Diuretics, Third space losses
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
No
 
 
 
 
Yes
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Measure urine sodium and serum osmolality
 
 
 
 
Measure urine sodium
 
 
25 to 40 mEq/L
• Infuse Isotonic saline 1 liter over 1 hour
• Remeasure urine sodium
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Urine Osm < 100
 
 
 
 
 
 
 
 
 
 
Hight > 40 mEq/L
Hypovolemic Hyponatremia
• Renal loss
 
 
 
 
 
 
 
 
 
 
 
Yes
 
 
 
 
 
 
 
 
 
 
No
 
Urine osmolality measured After therapy initiated
 
Yes
 
 
 
Use of diuretics
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Recovery from one of the followings:
• Mild hypovolemia(Patients given isotonic fluids
Hypopituitarism
(Patients given glucocorticoids))
 
 
 
Low cortisol,
Positive ACTH stimulation

Primary adrenal insufficiency
 
 
 
Urine Na > 40 mEq/L
 
No
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Head injury/surgery
Cerebral-salt wasting
 
 
 
 
 
 
 
No
 
Yes
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Patient with rapid water consumption
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Ensure that sodium intake > 150 mEq/L over next 24 hours (infuse 1 liter of isotonic fluid over one or more hour)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Remeasure urine osmolality and sodium
 
 
 
 
 
 
 
No
 
Yes
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
High-fluid
low-protein diet including:
Beer potomania
• Tea and toast diet
 
Water intoxication:
Psychosis
• Endurance activity (Marathone)
Ecstasy use
 
 
 
 
 
Urine Na >40 or
Urine Osm > 100
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Urine Na < 40 or
Urine Osm < 100
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hypovolemic Hyponatremia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Check for:
• Glucocorticoid deficiency with
Cortisol level and ACTH stimulationand
Hypothyroidism with TSH
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
check morning cortisol and
ACTH stimulation test
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Yes
 
No
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Glucocorticoid deficiency
 
Elevated TSH
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
No
 
 
Yes
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
SIAD
Nephrogenic SIAD
Reset Osmostat
 
 
Severe Hypothyroidism
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Evaluate underlying etiology
 
 
 
 
 
 
 
 
 

References

  1. F. S. Apple, D. D. Koch, S. Graves & J. H. Ladenson (1982). "Relationship between the direct-potentiometric and flame-photometric measurement of sodium in the blood". Clinical chemistry. 28 (9): 1931–1935. PMID 7127808. Unknown parameter |month= ignored (help)
  2. Hussain, Iram; Ahmad, Zahid; Garg, Abhimanyu (2015). "Extreme hypercholesterolemia presenting with pseudohyponatremia - a case report and review of the literature". Journal of Clinical Lipidology. 9 (2): 260–264. doi:10.1016/j.jacl.2014.11.007. ISSN 1933-2874.
  3. Adrogué, Horacio J.; Madias, Nicolaos E. (2014). "Diagnosis and Treatment of Hyponatremia". American Journal of Kidney Diseases. 64 (5): 681–684. doi:10.1053/j.ajkd.2014.06.001. ISSN 0272-6386.
  4. Sahay, Manisha; Sahay, Rakesh (2014). "Hyponatremia: A practical approach". Indian Journal of Endocrinology and Metabolism. 18 (6): 760. doi:10.4103/2230-8210.141320. ISSN 2230-8210.
  5. E. J. Hoorn, M. L. Halperin & R. Zietse (2005). "Diagnostic approach to a patient with hyponatraemia: traditional versus physiology-based options". QJM : monthly journal of the Association of Physicians. 98 (7): 529–540. doi:10.1093/qjmed/hci081. PMID 15955797. Unknown parameter |month= ignored (help)

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