Whole blood viscosity issue VIII: Comparison of extrapolation method with diagnostic digital viscometer
Ezekiel Uba Nwose1, 2, Ross Stuart Richards2
1Nepean Hospital Pathology, Derby Street, Kingswood, NSW 2747, Australia.
2School of Community Health, Charles Sturt University, Albury, NSW 2640 Australia.
Citation: Nwose EU, Richards RS. Whole blood viscosity issue VIII: Comparison of extrapolation method with diagnostic digital viscometer. North Am J Med Sci 2011; 3: 333-335.
Background: The first issue of this series proposed extrapolation chart with conventional reference range and suggested comparison of results with other methods. Aim: This work sets out to compare interpretative results from the extrapolation method with those from a digital viscometer method. Materials and Methods: Five cases in our archived clinical pathology database that were specifically tested for whole blood viscosity by the digital method, and had results for haematocrit and serum proteins were pooled. The values of haematocrit and serum proteins were used to derive extrapolated values. The interpretative results of the extrapolation method were compared with those of digital viscometer-based clinical reports. Non-Newtonian fluids such as whole blood have different viscosities at different shear rates. Comparative statement can only be based on interpreted outcome. Results: Two-fifth absolute concordance and one-fifth discordance is observed between extrapolation and viscometer-based clinical reports. The discordance is a case of hyperviscosity in the presence of neither hyperproteinaemia nor polycythemia. Conclusion: The extrapolation method may underestimate whole blood viscosity in some patients when compared with digital viscometer, which in turn may suggest hyperviscosity that cannot be explained by hyperproteinaemia or polycythemia concepts. The impact of oxidative stress is highlighted.
Keywords: Digital viscometer, extrapolation chart, whole blood viscosity.
Correspondence to: Dr. Uba Nwose, Institute of Clinical Pathology & Medical Research, Nepean Hospital Pathology, Derby Street, Kingswood, NSW 2747, Australia. Tel.: +612 47342178, Email: email@example.com