Comparison of four methods for determination of total protein concentrations in pleural and peritoneal fluid from dogs.

OBJECTIVE

To compare 4 techniques for determination of total protein concentrations in peritoneal and pleural effusions from dogs.

SAMPLE POPULATION

23 peritoneal and 12 pleural fluid samples from 35 dogs with various abnormalities.

PROCEDURE

Samples were collected into tubes containing EDTA, centrifuged, and stored at -20 C until total protein concentrations were assessed. Protein concentration in each sample was determined by use of urine test strips, refractometry, and Bradford and biuret techniques. Accuracy of each method was determined, using dilutions of human control sera.

RESULTS

There was good correlation among results of all quantitative procedures. Results of the biuret technique were more accurate than results of the Bradford assay. Refractometry underestimated protein concentration in samples with < 20 g of protein/L. Results of urine test strips correctly classified effusion samples into 2 groups on the basis of total protein concentrations less than or greater than 20 g/L.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of any of these 4 techniques can be used to rapidly and efficiently differentiate peritoneal and pleural fluid from dogs into transudates and exudates on the basis of total protein concentration less than or greater than 20 g/L, respectively.