Establishing Early Intervention Thresholds for High-Altitude Polycythemia: Evidence from a Cross-Sectional Study of Tibetan Residents

Zhuoga Danzeng, Luobu Gesang, Yangzong Suona, Yuansheng Wang, Yangjin Baima, Bai Ci, Ju Huang, Zhuoma Ciren, Rui Zhang, Binyun Liu, and Quzong Zhaxi. Establishing Early Intervention Thresholds for High-Altitude Polycythemia: Evidence from a Cross-Sectional Study of Tibetan Residents. High Alt Med Biol. 00:00–00, 2026. Background: High-altitude polycythemia (HAPC), defined by elevated hemoglobin levels, is a key feature of chronic mountain sickness, yet the “intermediate zone” preceding overt HAPC remains poorly understood. This cross-sectional study aimed to define evidence-based thresholds for early intervention in high-altitude populations. Methods: A total of 2,819 indigenous Tibetan residents (≥18 years) living at altitudes ≥ 4,500 m were classified into three groups based on hemoglobin levels: normal (males: 130–175 g/l; females: 115–150 g/l), intermediate (males: 175–210 g/l; females: 150–190 g/l), and HAPC (males: ≥210 g/l; females: ≥190 g/l). We assessed clinical phenotypes, organ function, and metabolic parameters through questionnaires, physical exams, biochemical analyses, and echocardiography. Logistic regression identified health risks for each group. Results: Revealed that participants in the intermediate and HAPC groups exhibited significant abnormalities compared with the normal group: increased waist circumference ( p < 0.001), elevated low-density lipoprotein cholesterol (LDL-C; p < 0.001), and higher uric acid levels ( p < 0.001), with an increased risk of hyperuricemia (OR = 2.077, p < 0.001). Additionally, SpO 2 was lower in the intermediate (83%) and HAPC (80%) groups, indicating worsening hypoxia ( p < 0.001). Organ function abnormalities included elevated ALT levels ( p < 0.001) and right ventricular wall thickness ( p = 0.025). Conclusion: These findings suggest that individuals in the intermediate zone exhibit early signs of organ dysfunction, indicating a “pre-HAPC state.” We advocate for a risk-stratified approach to early intervention in high-altitude illness.