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Adrogué–Madias: theoretical sodium change

Estimates the theoretical sodium change per litre of solution in the documented model. Does not calculate a prescription for volume, rate or correction target.

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Check the population, units and version. The result shows the formula or classification; it does not make an automatic treatment decision.

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Method · Limits of application

Adrogué–Madias 2000; theoretical change per 1 L

Static estimate in adults; does not calculate the volume needed to reach a target, rate, duration or safe correction limits. Does not include diuresis, losses or changes during treatment.

Conditions of use

Check the conditions of application before calculating. The result presents the documented formula or criteria; it does not establish a diagnosis or prescription.

Scope of this implementation

Static estimate in adults; does not calculate the volume needed to reach a target, rate, duration or safe correction limits. Does not include diuresis, losses or changes during treatment.

Parameters in this edition

Current sodium · mEq/L
Weight · kg
Estimated total body water fraction
Infused solution
Potassium added to the solution · mEq/L
Age · years

Sources and documentation

Method version

Adrogué–Madias 2000; theoretical change per 1 L

Formula and criteria

ΔNa per 1 L = (solution Na + solution K − serum Na)/(total body water + 1); total body water = weight × entered fraction.

Population and limitations

Static estimate in adults; does not calculate the volume needed to reach a target, rate, duration or safe correction limits. Does not include diuresis, losses or changes during treatment.

Synthetic cases checked (5)

Synthetic cases for checking the implementation, with no patient data.

Case 1

reference-001

Inputs

Current sodium: 120 mEq/L
Weight: 70 kg
Estimated total body water fraction: 0.60
Infused solution: NaCl 3% (Na 513 mEq/L)
Potassium added to the solution: 0 mEq/L
Age: 50 years

{
  "na": 120,
  "peso": 70,
  "grupo": "0.6",
  "sol": "ns3",
  "kadd": 0,
  "idade": 50
}

Expected result

{
  "delta": 9.13953488372093,
  "tbw": 42
}

Actual result

{
  "delta": 9.13953488372093,
  "tbw": 42
}

Case 2

reference-002

Inputs

Current sodium: 120 mEq/L
Weight: 70 kg
Estimated total body water fraction: 0.60
Infused solution: NaCl 0.9% (Na 154 mEq/L)
Potassium added to the solution: null mEq/L
Age: 50 years

{
  "na": 120,
  "peso": 70,
  "grupo": "0.6",
  "sol": "ns09",
  "kadd": null,
  "idade": 50
}

Expected result

{
  "delta": 0.7906976744186046,
  "tbw": 42
}

Actual result

{
  "delta": 0.7906976744186046,
  "tbw": 42
}

Case 3

reference-003

Inputs

Current sodium: 134 mEq/L
Weight: 70 kg
Estimated total body water fraction: 0.60
Infused solution: Lactated Ringer’s solution (Na 130, K 4 mEq/L)
Potassium added to the solution: 20 mEq/L
Age: 50 years

{
  "na": 134,
  "peso": 70,
  "grupo": "0.6",
  "sol": "rl",
  "kadd": 20,
  "idade": 50
}

Expected result

{
  "delta": 0.46511627906976744,
  "tbw": 42
}

Actual result

{
  "delta": 0.46511627906976744,
  "tbw": 42
}

Case 4

reference-004

Inputs

Current sodium: 140 mEq/L
Weight: 70 kg
Estimated total body water fraction: 0.60
Infused solution: Glucose 5% solution (no sodium)
Potassium added to the solution: null mEq/L
Age: 50 years

{
  "na": 140,
  "peso": 70,
  "grupo": "0.6",
  "sol": "sg5",
  "kadd": null,
  "idade": 50
}

Expected result

{
  "delta": -3.255813953488372,
  "tbw": 42
}

Actual result

{
  "delta": -3.255813953488372,
  "tbw": 42
}

Case 5

reference-005

Inputs

Current sodium: 130 mEq/L
Weight: 60 kg
Estimated total body water fraction: 0.45
Infused solution: NaCl 0.45% (Na 77 mEq/L)
Potassium added to the solution: 0 mEq/L
Age: 50 years

{
  "na": 130,
  "peso": 60,
  "grupo": "0.45",
  "sol": "ns045",
  "kadd": 0,
  "idade": 50
}

Expected result

{
  "delta": -1.8928571428571428,
  "tbw": 27
}

Actual result

{
  "delta": -1.8928571428571428,
  "tbw": 27
}

Source for the active edition

IAEM · Hyponatraemia guideline v1.0 · May 2024

Additional reading and history

Identifier: correcao-de-sodio-adrogue-madias

Original clinical content: Brazilian Portuguese.

Code and reproducibility

This tool’s code on GitHub

Download code and tests

Sources, version and reproduction instructions

README

Local installation

Code license: Apache-2.0

Guidelines and conditions

This repository’s license applies to the code. Third-party instruments, questionnaires, data and models remain subject to their owners’ conditions.

The code tests are technical checks. Clinical approval and professional translation review are recorded separately.

Relationship with cancer research

General context — relationship to be defined

A resource for general clinical contexts. This edition does not assign a specific oncological relationship; selecting it for a study requires a justified question, population and purpose.