Journal Article

Are coagulation profiles in Andean highlanders with excessive erythrocytosis favouring hypercoagulability?

Furian, Michael, Pichon, Aurélien, Champigneulle, Benoit, Stauffer, Émeric, Seyve, Landry, Bouzat, Pierre, Polack, Benoit, Robach, Paul, Marlu, Raphael, Hancco, Ivan, Kaestner, Lars, Caton, François, Verges, Samuel, Brugniaux, Julien V., Connes, Philippe, Deschamps, Blandine

2024

Overview

Chronic mountain sickness is a maladaptive syndrome that affects individuals living permanently at high altitude and is characterized primarily by excessive erythrocytosis (EE). Recent results concerning the impact of EE in Andean highlanders on clotting and the possible promotion of hypercoagulability, which can lead to thrombosis, were contradictory. We assessed the coagulation profiles of Andeans highlanders with and without excessive erythrocytosis (EE+ and EE−). Blood samples were collected from 30 EE+ and 15 EE− in La Rinconada (Peru, 5100–5300 m a.s.l.), with special attention given to the sampling pre‐analytical variables. Rotational thromboelastometry tests were performed at both native and normalized (40%) haematocrit using autologous platelet‐poor plasma. Thrombin generation, dosages of clotting factors and inhibitors were measured in plasma samples. Data were compared between groups and with measurements performed at native haematocrit in 10 lowlanders (LL) at sea level. At native haematocrit, in all rotational thromboelastometry assays, EE+ exhibited hypocoagulable profiles (prolonged clotting time and weaker clot strength) compared with EE− and LL (all P < 0.01). At normalized haematocrit, clotting times were normalized in most individuals. Conversely, maximal clot firmness was normalized only in FIBTEM and not in EXTEM/INTEM assays, suggesting abnormal platelet activity. Thrombin generation, levels of plasma clotting factors and inhibitors, and standard coagulation assays were mostly normal in all groups. No highlanders reported a history of venous thromboembolism based on the dedicated survey. Collectively, these results indicate that EE+ do not present a hypercoagulable profile potentially favouring thrombosis. What is the central question of this study? Are Andean highlanders with excessive erythrocytosis (EE+) exhibiting a hypercoagulable profile compared with highlanders without erythrocytosis (EE−) and lowlanders (LL)? What is the main finding and its importance? Despite normal plasma coagulation (thrombinography and levels of clotting factors and inhibitors), EE+ exhibited a hypocoagulable rotational thromboelastometry profile (prolonged clotting time and weaker clot strength) compared with EE− and LL. In EE+, haematocrit normalization at 40% corrected maximal clot firmness in rotational thromboelastometry FIBTEM tests, but not in EXTEM and INTEM tests, suggesting that platelets play a role in the native hypocoagulable profile.

• Publisher: John Wiley & Sons, Inc,Wiley-Blackwell,Wiley
• Subject: Adult / Altitude / Altitude Sickness - blood / Altitude Sickness - physiopathology / blood coagulation / Blood Coagulation - physiology / chronic mountain sickness / Clotting / Coagulation / excessive erythrocytosis / Female / Hematocrit / Hematocrit - methods / Human health and pathology / Humans / hypoxia / Life Sciences / Male / Middle Aged / Peru / Plasma / Platelets / Polycythemia / Polycythemia - blood / Thrombelastography - methods / Thrombin / Thrombin - metabolism / thromboelastometry / Thromboembolism / Thrombophilia - blood / Thrombosis