Review of interference indices in body fluid specimens submitted for clinical chemistry analyses

The aims of this study were to retrospectively investigate interference indices in a wide range of body fluid specimens and compare these indices to those found in serum/plasma.

This retrospective study evaluated interference indices for hemolysis, icterus, and lipemia in 2752 body fluid specimens submitted for clinical chemistry testing.

The distribution of interference indices for body fluid samples was generally similar to that of serum/plasma interference indices. Hemolysis of specimens submitted for lactate dehydrogenase (LD) represented the most common interference for body fluid chemistries. Body fluids collected from postsurgical drain sites had a higher proportion of tests exceeding both icterus and lipemic limits compared to serum/plasma specimens.

Overall, degrees of hemolysis, icterus, and lipemia observed in body fluid specimens were in large part similar to serum/plasma specimens, with a few notable differences. Body fluids exhibited a higher proportion of samples with severe icterus or lipemia. Severely lipemic body fluid samples were significantly less likely to also be hemolyzed relative to severely lipemic serum/plasma specimens. LD was the test most commonly affected by interference across all body fluid types. False elevations in pleural fluid LD induced by hemolysis can lead to mis-classification of transudative effusions as exudative using Light's criteria. The possible impact of interferences on clinical chemistry testing in body fluids is an important post-analytical consideration.