Abstract
OBJECTIVES: Several previous studies have described the effects of interfering substances on clinical assay results; however, the effects of exogenous substances, particularly additives from blood collection tubes on quality control (QC) specimens and serum specimens have not been well examined. This study examines the effects of blood-collection tube additives on total triiodothyronine (TT3), and thyroxine (TT4), cortisol, and routine clinical chemistry tests in QC and serum specimens from apparently healthy volunteers. METHODS: QC and serum specimens were poured or collected into different blood collection tubes. TT3 and TT4, cortisol, and routine chemistry tests were analyzed from the different blood-collection tube types. RESULTS: The findings of this study demonstrate statistically and/or clinically significant blood collection tube-related alterations in the TT3, TT4, and cortisol concentrations of QC specimens and TT4 concentrations from serum specimens. CONCLUSIONS: These findings have important implications for clinical laboratories, demonstrating that QC specimens should ideally, like patients' specimens, be poured into blood collection tubes. This strategy would reveal any adverse effects caused by blood collection tubes, which otherwise would not likely be detected by most routine QC practices. The results of this study also show the importance of producing blood collection tubes that contain additives that are truly inert and do not adversely affect clinical laboratory testing.