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(OR19-05-26) Residence at Moderate Altitude Duty Stations (~1,800 M) Increases Hemoglobin Mass and Requires Altitude-Adjusted Anemia Cutoffs for Operational Readiness

Monday, July 27, 2026
11:18 AM - 11:30 AM ET
Location: National Harbor 4-5
Disclosure(s):
Cory Dugan, PhD: No relevant financial relationship(s) with ineligible companies to disclose.
David E. Barney, PhD, Jr.: No relevant financial relationship(s) with ineligible companies to disclose.
Claire Berryman, PhD, RD: Eli Lilly: Stock Shareholder (excluding mutual funds) (Ongoing)
Objectives: Military Service Members stationed or deployed at altitudes above sea level may experience reduced oxygen availability, which can stimulate hematological adaptations such as increases in total hemoglobin mass (tHbmass). Distinguishing true erythropoietic adaptation from plasma volume changes, and applying altitude-adjusted hemoglobin cutoffs, is essential for accurate assessment of anemia and operational readiness. The objective of this study was to assess differences in hemoglobin concentration, tHbmass, plasma volume, and anemia prevalence between active-duty Service Members stationed at moderate altitude or sea level.

Methods: This cross-sectional analysis of the Military Health and Nutrition Examination Study (MHANES) included 230 Army Service Members (25% female) stationed at sea level (n=140, ≤120 m) or moderate altitude (n=90, 1,800 m). Fasted venous blood was collected to determine hemoglobin concentration, and tHbmass and plasma volume were assessed by the automated carbon monoxide rebreathing method. Body composition was assessed by bioelectrical impedance. Anemia cutoffs were adjusted for 1,800 m using the 2024 WHO guidelines. Differences between altitude residence were assessed by ANCOVA with sex as a covariate; values are estimated marginal means ± SE.

Results: Most participants (73%) resided at their duty station for more than one year. Hemoglobin concentration was elevated by 7% at moderate altitude compared to sea level (150.7 ± 1.1 vs 141.0 ± 1.0 g/L, p< 0.001). Moderate altitude residents had higher tHbmass compared to sea level residents (12.6 ± 0.2 vs 11.6 ± 0.1 g/kg lean body mass, p< 0.001). Plasma volume did not differ between groups (47.4 ± 0.6 vs 48.3 ± 0.5 mL/kg lean body mass, p=0.179). The prevalence of anemia at moderate altitude was 1.1% (vs 5.0% at sea level) and increased to 7.8% when applying altitude-adjusted hemoglobin cutoffs.

Conclusions: Findings suggest that residence at moderate altitude induces genuine erythropoietic adaptation characterized by increased tHbmass, independent of plasma volume changes. Altitude-adjusted hemoglobin cutoffs identified a substantially higher prevalence of anemia, with implications for screening protocols and operational readiness assessment in altitude-stationed personnel.

Funding Sources: USAMRDC; views expressed are not official US Army, DoW, or government policy.