is a worthwhile goal, there should be no compromise on patient care. There is immense scope for education on clinical viscosity testing to be enhanced and improved to incorporate its full potential and to raise the vision in the possibilities it has to improve patient outcomes and to provide invaluable information to clinicians. Incorporating clinical viscosity testing globally into associated condition pathways will encourage and ensure clinical excellence, consistency and equity for patients.

What has changed? Two things have changed. First, clinical capillary viscometers have continued to develop, and now clinical viscosity analysers are available with advanced health and safety features, increased throughput, improved reliability, and most importantly improved precision. There are now true load-up and walkaway analysers that sample from a sealed cap on primary (draw) tubes to avoid potential biohazards, which incorporate software to perform auto-calibration and quality control checks between every few samples to monitor for drift. Viscometers specifically designed and manufactured for clinical use should be the only standard any healthcare provider accepts. The second change is COVID-19. Clinicians around the world are trying to establish a strategy to determine which patients infected with SARS CoV-2 develop severe non-respiratory complications. So far, the key screening test appears to be the PV test. As stated in the introduction, patients suffering with severe COVID-19 symptoms have a greatly raised PV level. This is to be expected because they will develop an acute-phase response and produce a mega response with fibrinogen levels up to 10 times normal, with a subsequent rise in PV to levels only previously seen in patients with hyperviscosity syndrome. Recent research illustrates a significant change in some of these parameters in the immediate time leading up to symptoms developing. This potentially is an exciting finding and might save the lives of many patients by early diagnosis and specific targeted treatment. Leading hospitals are exploring how best to understand and treat COVID-19. They have been carrying out PV tests on suspected COVID-19 patients to establish a link between PV and COVID-19, and to explore how PV relates to the severity of and/or recovery from the disease. This has extended to ensuring anti-platelet drug therapy efficacy by monitoring the inflammatory status in those with high-risk transient ischaemic attacks (TIAs) commenced on dual anti-platelet therapy,


Over the past 50 years in the UK, plasma viscosity has been, and still can be, used to screen for and monitor paraproteinaemias such as myeloma (haematoxylin and eosin [H&E] stain).

those not responding as expected on anti-platelet therapy, and those with high-risk carotid/vertebral or intracranial stenosis. Increased blood viscosity is an indicator for potential stroke and heart attack induced by a low flow of blood in the capillaries leading to an inadequate delivery of vital oxygen and nutrients to body tissues.

Haematology experts have stated that while there are alternative tests for inflammation and infection, none surpass the accuracy, precision, and suitability of PV for diagnosis and monitoring. There is a constant flow of new applications for PV, SV and red cell deformability on an almost daily basis and none more so than in the current climate of battling COVID-19. With the USA seeing many COVID-19 patients, clinical establishments are undertaking research into the condition and are publishing papers with PV data; some using outdated, cumbersome equipment inherited from the petrochemical industry. Now, USA medical centres are starting to look to the UK for state-of-the-art clinical equipment9


will allow them to analyse high-risk clinical samples rapidly and safely. And when the USA leads, the rest of the world follows.

References 1 Maier CL, Truong AD, Auld SC, Polly DM,

Tanksley CL, Duncan A. COVID-19- associated hyperviscosity: a link between inflammation and thrombophilia? Lancet 2020; 395 (10239): 1758–9.

2 Guidelines on selection of laboratory tests for monitoring the acute phase response. International Committee for Standardization in Haematology (expert panel on blood


rheology). J Clin Pathol 1988; 41 (11): 1203–12. doi: 10.1136/jcp.41.11.1203.

3 Gloucestershire Hospitals NHS Foundation Trust. Plasma viscosity ( services-we-offer/pathology/tests-and- investigations/plasma-viscosity).

4 Gudmundsson M, Nordborg E, Bengtsson BA, Bjelle A. Plasma viscosity in giant cell arteritis as a predictor of disease activity. Ann Rheum Dis 1993; 52 (2): 104–9.

5 Finke C, Schroeter J, Kalus U, Ploner CJ. Plasma viscosity in giant cell arteritis. Eur Neurol 2011; 66 (3):159–64.

6 Koshiaris C, Van den Bruel A, Oke JL et al. Early detection of multiple myeloma in primary care using blood tests: a case-control study in primary care. Br J Gen Pract 2018; 68 (674): e586–e593. doi: 10.3399/bjgp18X698357.

7 Tuddenham EG, Whittaker JA, Bradley J, Lilleyman JS, James DR. Hyperviscosity syndrome in IgA multiple myeloma. Br J Haematol 1974; 27 (1): 65–76. doi: 10.1111/j.1365-2141.1974.tb06775.x. ( 10.1111/j.1365-2141.1974.tb06775.x).

8 Watson J, de Salis I, Hamilton W, Salisbury C. ‘I’m fishing really’ – inflammatory marker testing in primary care: a qualitative study. Br J Gen Pract 2016; 66 (644): e200–6. doi: 10.3399/bjgp16X683857 (

9 Anon. Plasma viscosity in COVID-19 disease: a vital monitoring role. Pathology in Practice 2020 Jun; 21 (3): 46–8.

Further information on viscometry and Benson Viscometers is available from Lorna Chun (General Manager). Email: Tel: +44 (0)1646 650065.



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