Felis ISSN 2398-2950

Peritoneal fluid: protein

Contributor(s): Yvonne McGrotty

Overview

  • Protein content varies with changes in vascular permeability and tissue injury or chemotaxis.
  • Protein is elevated in inflammatory effusions, assists differentiation of transudates and exudates.

Sampling

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Tests

Methodologies

  • Refractometry:
    • A drop of fluid is placed on refractometer plate.
    • If fluid is opaque best to centrifuge first and measure protein of supernatent.
    • Most refractometers are calibrated to give a reading for total protein in g/dl. Multiply 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.
  • Precipitation and dye binding methods.
  • Urinary protein reagent strips for detection of grossly elevated total protein. 
  • Alternatively the protein may be measured using biochemical analyzer.

Availability

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

Technique (intrinsic) limitations

  • Presence of a high concentration of other solutes, eg lipids, 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

Other sources of information

  • M D Willard (1989) Fluid accumulation disorders. In: Small Animal Clinical Diagnosis by Laboratory Methods. Willard, Tvedten & Turmwald (eds) 1st edn, Saunders. pp 229-242.


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