ANNALS EXPRESS: Plasma viscosity: Evaluation of a new measuring method using microfluidic chip technology (microVisc) for clinical use and determination of a new reference range.

Background Plasma viscosity is an important biomarker both in diagnostics and treatment monitoring of plasma cell dyscrasias and other disorders with hyperviscosity syndrome as a clinical manifestation. Here, we investigate the performance of a new microfluidic-based viscometer for clinical use, establish a new reference range to be used with this instrument and determine the importance of sampling temperature. Methods The microVisc (TM) viscometer was evaluated for within-run and between-run imprecision and bias using standardized reference material (Paragon controls) and Seronorm (TM) control material. The reference range was established for the adult population using EDTA-plasma from 120 healthy blood donors. Sampling temperature was investigated by drawing and transporting blood at room temperature and 37 degrees C and comparing the viscosity between the two sampling methods. Results The microfluidic-based viscometer performed well, and imprecision was comparable to ReoRox (R) G2 free oscillation rheometer. A new reference range for the adult Danish population was established as 1.2-1.5 mPa s at 37 degrees C. Furthermore, sampling temperature at room temperature and 37 degrees C was investigated, and there was no difference in results obtained. Conclusions MicroVisc (TM) is suitable for measuring plasma viscosity in a clinical setting and results can be evaluated using the established reference range. Blood sampling for viscosity analysis can be performed as a standard procedure at room temperature.