Lights Criteria Calculator

Use the Lights Criteria Calculator to determine the nature of pleural effusions, distinguishing between transudative and exudative effusions based on the Light's criteria.

Full original guide (expanded)

Lights Criteria Calculator

Classify pleural effusions as transudative or exudative using standard Light's criteria.

Calculator

Results

Pleural Effusion Type:

Data Source and Methodology

All calculations are based on the Light's criteria as described in the medical literature. Read more about Light's criteria. All calculations are strictly based on the formulas and data provided by this source.

The Formula Explained

Protein Ratio: \(\frac{\text{Pleural Fluid Protein}}{\text{Serum Protein}}\) > 0.5

LDH Ratio: \(\frac{\text{Pleural Fluid LDH}}{\text{Serum LDH}}\) > 0.6

LDH Level: Pleural Fluid LDH > 2/3 of upper normal limit for serum

Glossary of Variables

  • Pleural Fluid Protein: Concentration of protein in pleural fluid.
  • Serum Protein: Concentration of protein in blood serum.
  • Pleural Fluid LDH: Level of lactate dehydrogenase in pleural fluid.
  • Serum LDH: Level of lactate dehydrogenase in blood serum.

How It Works: A Step-by-Step Example

Consider a patient with a pleural fluid protein of 3.0 g/dL, serum protein of 6.0 g/dL, pleural fluid LDH of 200 IU/L, and serum LDH of 400 IU/L. The calculations would be:

  • Protein Ratio: \(3.0 / 6.0 = 0.5\)
  • LDH Ratio: \(200 / 400 = 0.5\)
  • If the pleural fluid LDH > 2/3 of the upper normal limit for serum, the effusion is exudative.

Frequently Asked Questions (FAQ)

What is Light's Criteria?

Light's criteria is a set of measurements used to differentiate between exudative and transudative pleural effusions.

How accurate is the Light's Criteria Calculator?

The calculator is based on well-established medical guidelines and provides an accurate assessment based on the input data.

Can the calculator be used for other types of effusions?

No, the calculator is specifically designed for pleural effusions.

What should I do if the result is unclear?

Consult with a medical professional for further diagnosis and interpretation.

How often should I re-evaluate effusion types?

Re-evaluation depends on the patient's condition and should be guided by clinical judgment.


Audit: Complete
Formula (LaTeX) + variables + units
This section shows the formulas used by the calculator engine, plus variable definitions and units.
Formula (extracted LaTeX)
\[','\]
','
Variables and units
  • No variables provided in audit spec.
Sources (authoritative):
Changelog
Version: 0.1.0-draft
Last code update: 2026-01-19
0.1.0-draft · 2026-01-19
  • Initial audit spec draft generated from HTML extraction (review required).
  • Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
  • Confirm sources are authoritative and relevant to the calculator methodology.
Verified by Ugo Candido on 2026-01-19
Profile · LinkedIn

Lights Criteria Calculator

Classify pleural effusions as transudative or exudative using standard Light's criteria.

Calculator

Results

Pleural Effusion Type:

Data Source and Methodology

All calculations are based on the Light's criteria as described in the medical literature. Read more about Light's criteria. All calculations are strictly based on the formulas and data provided by this source.

The Formula Explained

Protein Ratio: \(\frac{\text{Pleural Fluid Protein}}{\text{Serum Protein}}\) > 0.5

LDH Ratio: \(\frac{\text{Pleural Fluid LDH}}{\text{Serum LDH}}\) > 0.6

LDH Level: Pleural Fluid LDH > 2/3 of upper normal limit for serum

Glossary of Variables

  • Pleural Fluid Protein: Concentration of protein in pleural fluid.
  • Serum Protein: Concentration of protein in blood serum.
  • Pleural Fluid LDH: Level of lactate dehydrogenase in pleural fluid.
  • Serum LDH: Level of lactate dehydrogenase in blood serum.

How It Works: A Step-by-Step Example

Consider a patient with a pleural fluid protein of 3.0 g/dL, serum protein of 6.0 g/dL, pleural fluid LDH of 200 IU/L, and serum LDH of 400 IU/L. The calculations would be:

  • Protein Ratio: \(3.0 / 6.0 = 0.5\)
  • LDH Ratio: \(200 / 400 = 0.5\)
  • If the pleural fluid LDH > 2/3 of the upper normal limit for serum, the effusion is exudative.

Frequently Asked Questions (FAQ)

What is Light's Criteria?

Light's criteria is a set of measurements used to differentiate between exudative and transudative pleural effusions.

How accurate is the Light's Criteria Calculator?

The calculator is based on well-established medical guidelines and provides an accurate assessment based on the input data.

Can the calculator be used for other types of effusions?

No, the calculator is specifically designed for pleural effusions.

What should I do if the result is unclear?

Consult with a medical professional for further diagnosis and interpretation.

How often should I re-evaluate effusion types?

Re-evaluation depends on the patient's condition and should be guided by clinical judgment.


Audit: Complete
Formula (LaTeX) + variables + units
This section shows the formulas used by the calculator engine, plus variable definitions and units.
Formula (extracted LaTeX)
\[','\]
','
Variables and units
  • No variables provided in audit spec.
Sources (authoritative):
Changelog
Version: 0.1.0-draft
Last code update: 2026-01-19
0.1.0-draft · 2026-01-19
  • Initial audit spec draft generated from HTML extraction (review required).
  • Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
  • Confirm sources are authoritative and relevant to the calculator methodology.
Verified by Ugo Candido on 2026-01-19
Profile · LinkedIn

Lights Criteria Calculator

Classify pleural effusions as transudative or exudative using standard Light's criteria.

Calculator

Results

Pleural Effusion Type:

Data Source and Methodology

All calculations are based on the Light's criteria as described in the medical literature. Read more about Light's criteria. All calculations are strictly based on the formulas and data provided by this source.

The Formula Explained

Protein Ratio: \(\frac{\text{Pleural Fluid Protein}}{\text{Serum Protein}}\) > 0.5

LDH Ratio: \(\frac{\text{Pleural Fluid LDH}}{\text{Serum LDH}}\) > 0.6

LDH Level: Pleural Fluid LDH > 2/3 of upper normal limit for serum

Glossary of Variables

  • Pleural Fluid Protein: Concentration of protein in pleural fluid.
  • Serum Protein: Concentration of protein in blood serum.
  • Pleural Fluid LDH: Level of lactate dehydrogenase in pleural fluid.
  • Serum LDH: Level of lactate dehydrogenase in blood serum.

How It Works: A Step-by-Step Example

Consider a patient with a pleural fluid protein of 3.0 g/dL, serum protein of 6.0 g/dL, pleural fluid LDH of 200 IU/L, and serum LDH of 400 IU/L. The calculations would be:

  • Protein Ratio: \(3.0 / 6.0 = 0.5\)
  • LDH Ratio: \(200 / 400 = 0.5\)
  • If the pleural fluid LDH > 2/3 of the upper normal limit for serum, the effusion is exudative.

Frequently Asked Questions (FAQ)

What is Light's Criteria?

Light's criteria is a set of measurements used to differentiate between exudative and transudative pleural effusions.

How accurate is the Light's Criteria Calculator?

The calculator is based on well-established medical guidelines and provides an accurate assessment based on the input data.

Can the calculator be used for other types of effusions?

No, the calculator is specifically designed for pleural effusions.

What should I do if the result is unclear?

Consult with a medical professional for further diagnosis and interpretation.

How often should I re-evaluate effusion types?

Re-evaluation depends on the patient's condition and should be guided by clinical judgment.


Audit: Complete
Formula (LaTeX) + variables + units
This section shows the formulas used by the calculator engine, plus variable definitions and units.
Formula (extracted LaTeX)
\[','\]
','
Variables and units
  • No variables provided in audit spec.
Sources (authoritative):
Changelog
Version: 0.1.0-draft
Last code update: 2026-01-19
0.1.0-draft · 2026-01-19
  • Initial audit spec draft generated from HTML extraction (review required).
  • Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
  • Confirm sources are authoritative and relevant to the calculator methodology.
Verified by Ugo Candido on 2026-01-19
Profile · LinkedIn
Formulas

(Formulas preserved from original page content, if present.)

Version 0.1.0-draft
Citations

Add authoritative sources relevant to this calculator (standards bodies, manuals, official docs).

Changelog
  • 0.1.0-draft — 2026-01-19: Initial draft (review required).