Felis ISSN 2398-2950

Pleural fluid: protein

Contributor(s): Karen L Gerber, Andy Torrance, Kim Willoughby

Overview

  • Total protein Blood biochemistry: total protein varies with changes in vascular permeability, osmotic pressure and tissue injury.
  • Protein is elevated in exudates.
  • Used in conjunction with other laboratory tests on pleural fluid to diagnose the type of pleural effusion.

Sampling

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Tests

Methodologies

  • Refractometry.
  • If fluid is opaque, best to centrifuge first and measure protein of supernatent.
  • A drop of pleural fluid is placed on refractometer plate.
  • Reading is based on refractive index (RI) but calibrated in g/dl.
  • The RI changes proportionally to changes in protein concentration.
  • Alternatively, the protein may be measured using a biochemical analyzer.
  • Laboratory will indicate valid protein range for their instrument.

Availability

  • Standard practice laboratory procedure.

Technique (intrinsic) limitations

  • Presence of a high concentration of other solutes, eg lipids in chylothorax, can give a false high reading.
  • Lipemic fluids often do not separate sufficiently following centrifugation.

Result Data

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Further Reading

Publications

Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Hawkins E C et al(1986) Immunoglobulin A myeloma in a cat with pleural effusion and serum hyperviscosity. JAVMA 188(8), 876-878.

Other sources of information

  • Willard M D (1989) Fluid accumulation disorders. In: Small Animal Clinical Diagnosis by Laboratory Methods. 1st edn. Eds: M D Willard, Tvedton & Turnwald. Philadelphia: W B Saunders. pp 229-242.


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