Canis ISSN: 2398-2942

Pleural fluid: protein

Contributor(s): Yvonne McGrotty

Overview

  • Total protein varies with changes in vascular permeability, osmotic pressure and tissue injury or chemotaxis.
  • Pleural fluid protein is elevated in inflammatory processes.
  • Used in conjunction with other laboratory tests on pleural fluid to diagnose the type of pleural effusion Pleural: effusion.

Sampling

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Tests

Methodologies

  • Refractometry:
    • A drop of fluid is placed on refractometer plate.
    • Most refractometers are calibrated to give a reading for total protein in g/dl. Multiply result by 10 to convert to g/l.
    • Refractometry measures the refractive index (RI) of the fluid.
    • The RI changes proportionally to changes in protein concentration.
  • Precipation and dye binding methods.
  • Urinary protein re-agent strips for detection of grossly elevated total protein.

Availability

  • Widely available at commercial laboratories.
  • Refractometry can be performed in house.

Technique (intrinsic) limitations

  • It is assumed that there are no significant changes in the concentration of other solutes such as glucose, urea, lipids, etc which could, if elevated, give a false high reading by refractromety.
  • Pleural fluid must be clear for refractometry. For example, presence of hemoglobin can raise readings.

Result Data

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Further Reading

Publications

Refereed papers


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