Hyponatremia diagnostic study of choice

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Diagnostic Study of Choice
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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

• The page name should be "[Disease name] diagnostic study ", with only the first letter of the title capitalized. Note that the page is called "Diagnostic study of choice."
• Goal:
  • To describe the most efficient/sensitive/specific test that is utilized for diagnosis of [disease name].
  • To describe the gold standard test for the diagnosis of [disease name].
  • To describe the diagnostic criteria, which may be based on clinical findings, physical exam signs, pathological findings, lab findings, findings on imaging, or even findings that exclude other diseases.
• As with all microchapter pages linking to the main page, at the top of the edit box put {{CMG}}, your name template, and the microchapter navigation template you created at the beginning.
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• Remember to follow the same format and capitalization of letters as outlined in the template below.
• You should include the name of the disease in the first sentence of every subsection.

Template statements

flame photometer or an ion selective, electrode that requires sample dilution before assay .

Gold standard/Study of choice:

• [Name of the investigation] is the gold standard test for the diagnosis of [disease name].
• The following result of [gold standard test] is confirmatory of [disease name]:
  • Result 1
  • Result 2
• The [name of the investigation] should be performed when:
  • The patient presented with symptoms/signs 1. 2, 3.
  • A positive [test] is detected in the patient.
• [Name of the investigation] is the gold standard test for the diagnosis of [disease name].
• The diagnostic study of choice for [disease name] is [name of the investigation].
• There is no single diagnostic study of choice for the diagnosis of [disease name].
• There is no single diagnostic study of choice for the diagnosis of [disease name], but [disease name] can be diagnosed based on [name of the investigation 1] and [name of the investigation 2].
• [Disease name] is mainly diagnosed based on clinical presentation.
• Investigations:
  • Among patients who present with clinical signs of [disease name], the [investigation name] is the most specific test for the diagnosis.
  • Among patients who present with clinical signs of [disease name], the [investigation name] is the most sensitive test for diagnosis.
  • Among patients who present with clinical signs of [disease name], the [investigation name] is the most efficient test for diagnosis.

The comparison table for diagnostic studies of choice for [disease name]

	Sensitivity	Specificity
Test 1	✔	...%
Test 2	...%	✔

✔= The best test based on the feature

Diagnostic results

The following result of [investigation name] is confirmatory of [disease name]:

• Result 1
• Result 2

Sequence of Diagnostic Studies

Biochemical evaluation for finding the etiologies of hyponatremia :

The unnamed parameter 2= is no longer supported. Please see the documentation for {{columns-list}}.

2

For differential diagnosis click here.

Diagnostic Approach to Hyponatremia

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) • 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

• Here you should describe the details of the diagnostic criteria.
• Always mention the name of the criteria/definition you are about to list (e.g. modified Duke criteria for the diagnosis of endocarditis / 3rd universal definition of MI) and cite the primary source of where this criteria/definition is found.
• Although not necessary, it is recommended that you include the criteria in a table. Make sure you always cite the source of the content and whether the table has been adapted from another source.
• Be very clear as to the number of criteria (or threshold) that needs to be met out of the total number of criteria.
• Distinguish criteria based on their nature (e.g. clinical criteria / pathological criteria/ imaging criteria) before discussing them in details.
• To view an example (endocarditis diagnostic criteria), click here
• If relevant, add additional information that might help the reader distinguish various criteria or the evolution of criteria (e.g. original criteria vs. modified criteria).
• You may also add information about the sensitivity and specificity of the criteria, the pre-test probability, and other figures that may help the reader understand how valuable the criteria are clinically.
• [Disease name] is mainly diagnosed based on clinical presentation. There are no established criteria for the diagnosis of [disease name].
• There is no single diagnostic study of choice for [disease name], though [disease name] may be diagnosed based on [name of criteria] established by [...].

• The diagnosis of [disease name] is made when at least [number] of the following [number] diagnostic criteria are met: [criterion 1], [criterion 2], [criterion 3], and [criterion 4].
• The diagnosis of [disease name] is based on the [criteria name] criteria, which includes [criterion 1], [criterion 2], and [criterion 3].

• [Disease name] may be diagnosed at any time if one or more of the following criteria are met:
  • Criteria 1
  • Criteria 2
  • Criteria 3

IF there are clear, established diagnostic criteria:

• The diagnosis of [disease name] is made when at least [number] of the following [number] diagnostic criteria are met: [criterion 1], [criterion 2], [criterion 3], and [criterion 4].
• The diagnosis of [disease name] is based on the [criteria name] criteria, which include [criterion 1], [criterion 2], and [criterion 3].
• The diagnosis of [disease name] is based on the [definition name] definition, which includes [criterion 1], [criterion 2], and [criterion 3].

IF there are no established diagnostic criteria: 

• There are no established criteria for the diagnosis of [disease name].