Blood Viscosity in Polycythemia Patients

Polycythemia (PG) corresponds to an increase in erythrocyte parameters on a blood test. A distinction is usually made between primary and secondary PG. The most common primary PG is Vaquez's disease, a hematological cancer. In Vaquez disease, an increase in hematocrit has been reported to be associated with a logarithmic increase in blood viscosity. The main complications of primary PGs (especially in Vaquez disease) are thromboembolic complications. In contrast, thromboembolic complications are rarer in secondary PG. In Vaquez disease, a hematocrit ≤ 45% has been defined as the therapeutic goal for significantly reducing thromboembolic risk. However, this has not been established for secondary PGs. All in all, the definition of the 45% threshold is based solely on clinical studies with no obvious biological argument. What's more, simply lowering blood mass through cytoreduction alone does not appear to be sufficient to significantly reduce thromboembolic risk. To investigator knowledge, there are no studies prospectively evaluating blood viscosity, its determinants and coagulation in different types of polycythemia. Nor are there any data on the direct effect on blood viscosity of the various treatments usually offered.

Sex

All

Minimum age

18 Years

Inclusion Criteria:

* 18 years of age or older
* Followed for a diagnosis or suspicion of polycythemia (hematocrit greater than or equal to 49% in men and 48% in women), whatever the suspected etiology.
* Patient affiliated to a social security scheme or similar

Exclusion Criteria:

* Patient having undergone therapeutic bloodletting within 3 months prior to inclusion, or having initiated cytoreductive therapy prior to inclusion.
* Any disease or condition other than polycythemia, chronic or not, likely to induce a change in blood viscosity (at the investigator's discretion)
* Patient participating in another interventional research protocol that may interfere with the present protocol (at the investigator's discretion).
* Patient under guardianship, curatorship or safeguard of justice
* Person under psychiatric care
* Patient under legal protection.

• BACKGROUNDMarchioli R, Finazzi G, Specchia G, Cacciola R, Cavazzina R, Cilloni D, De Stefano V, Elli E, Iurlo A, Latagliata R, Lunghi F, Lunghi M, Marfisi RM, Musto P, Masciulli A, Musolino C, Cascavilla N, Quarta G, Randi ML, Rapezzi D, Ruggeri M, Rumi E, Scortechini AR, Santini S, Scarano M, Siragusa S, Spadea A, Tieghi A, Angelucci E, Visani G, Vannucchi AM, Barbui T; CYTO-PV Collaborative Group. Cardiovascular events and intensity of treatment in polycythemia vera. N Engl J Med. 2013 Jan 3;368(1):22-33. doi: 10.1056/NEJMoa1208500. Epub 2012 Dec 8. PMID 23216616
• BACKGROUNDVogel J, Kiessling I, Heinicke K, Stallmach T, Ossent P, Vogel O, Aulmann M, Frietsch T, Schmid-Schonbein H, Kuschinsky W, Gassmann M. Transgenic mice overexpressing erythropoietin adapt to excessive erythrocytosis by regulating blood viscosity. Blood. 2003 Sep 15;102(6):2278-84. doi: 10.1182/blood-2003-01-0283. Epub 2003 May 15. PMID 12750170
• BACKGROUNDWade JP, du Boulay GH, Marshall J, Pearson TC, Russell RW, Shirley JA, Symon L, Wetherley-Mein G, Zilkha E. Cerebral blood flow, haematocrit and viscosity in subjects with a high oxygen affinity haemoglobin variant. Acta Neurol Scand. 1980 Apr;61(4):210-5. doi: 10.1111/j.1600-0404.1980.tb01485.x. PMID 7376820
• BACKGROUNDBarbui T, De Stefano V, Ghirardi A, Masciulli A, Finazzi G, Vannucchi AM. Different effect of hydroxyurea and phlebotomy on prevention of arterial and venous thrombosis in Polycythemia Vera. Blood Cancer J. 2018 Nov 26;8(12):124. doi: 10.1038/s41408-018-0161-9. No abstract available. PMID 30478311
• RESULTPearson TC. Hemorheology in the erythrocytoses. Mt Sinai J Med. 2001 May;68(3):182-91. PMID 11373690