Impact of Haemoglobin and Haematocrit on the Incidence of Thrombosis in the Individuals Exposed to High-Altitude

Abstract

Objective: To investigate the association among high haemoglobin (Hb), high hematocrit (HCT), and thrombosis in individuals exposed to high-altitude (HA) environments, contributing to our understanding of haematological changes and thrombotic risk associated with HA exposure. Study Design: Retrospective longitudinal study Place and Duration of Study: High Altitude Medical and Research Cell (HALMARC) Pakistan, from Jan 2021 and Dec 2022. Methodology: The total number of 91 participants who were exposed to high-altitude were included. All age groups were included. Participants were categorized based on altitude, stay duration, Hb, and HCT levels. All types of thrombotic events were recorded. Results: Participants were exposed to altitudes ranging from less than 15,000 feet to greater than 18,000 feet, with varying durations of stay. The majority of the male participants were non-smokers. The mean Hb was 16.76±2.03 g/dl, and the mean HCT was 52.17±6.1%. More than half (53%) of the participants experienced thrombosis, with most cases involving brain thrombosis. However, there was no significant effect of elevated Hb (p=0.10) or HCT (p=0.75) on the incidence of thrombosis. Conclusion: Extended stays at high altitudes were associated with elevated hematocrit levels. However, no direct association was found between high Hb and HCT levels and the incidence of thrombosis. Thrombotic events at high altitudes are likely influenced by multifactorial factors beyond haematological parameters, including individual variations in blood coagulation, genetics, and environmental influences.

Keywords

• Haemoglobin
• Haematocrit
• High-altitude
• Thrombosis