Blood viscosity and clotting risk in people with polycythemia
Official title: Evaluation of Blood Viscosity and Hyperviscosity-related Complications Relationship in Patients With Patients With Polycythemia
Run by Hospices Civils de Lyon · NCT06421025 · Data updated 2026-11-12
This study will see if measuring blood thickness and clotting tests can help explain who is more likely to develop blood clots among adults with primary or secondary polycythemia.
Quick facts
| Study type | Observational |
|---|---|
| Ages | 18 Years and up |
| Sex | All |
| Enrollment | 160 (estimated) |
| Sponsor | Hospices Civils de Lyon Academic / other |
| Locations | 1 site (Pierre-Bénite, Lyon) |
| Status | Recruiting |
| Started | September 10, 2024 |
| Main results expected | September 10, 2031 |
| Study ends | September 10, 2031 |
| Registry record updated | November 21, 2025 |
| Trial ID | NCT06421025 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Adults (18+) who are being followed for suspected or confirmed polycythemia with hematocrit ≥49% in men or ≥48% in women and who are able to attend Hôpital Lyon Sud and are covered by a social security scheme are ideal candidates.
✕Probably not a fit
People who recently had therapeutic phlebotomy or started cytoreductive therapy, those with other conditions that change blood viscosity, minors, or individuals under legal protection are unlikely to benefit from participation.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This is a single-center observational study at Hôpital Lyon Sud enrolling adults followed for suspected or confirmed polycythemia to measure blood viscosity, thromboelastometry, and related laboratory markers. Researchers will compare these physiological measurements across primary (including Vaquez disease) and secondary polycythemia and relate them to hematocrit levels and thrombotic history. The protocol excludes people who had therapeutic bloodletting or started cytoreductive therapy within three months, those with other conditions likely to change viscosity, and individuals under legal protection. No investigational treatments are given; data are collected from clinical visits and laboratory testing to explore biological links between hematocrit, viscosity, and clotting risk.
Why it matters
Potential benefit: If successful, the findings could help personalize hematocrit targets and improve prediction of thrombotic risk for people with polycythemia.
How similar studies have gone: Previous clinical studies have linked higher hematocrit to increased blood viscosity and clotting risk in primary polycythemia (Vaquez), but applying viscosity and thromboelastometry measurements to refine risk thresholds—especially in secondary polycythemia—is less established.
Who can join: the full rules
Show full inclusion / exclusion criteria
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.
Where it's running
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Service d'hématologie, Hôpital Lyon Sud
Pierre-Bénite, Lyon, France Recruiting
Study contacts
- Study coordinator: Mael HEIBLIG, MD,PhD
- Email: mael.heiblig@chu-lyon.fr
- Phone: 478862240
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.