Author(s): GEERTS, N., STACEY, B.S., BROWN, C., PATRICIAN, A., PURCELL, S., MAIER, L., OSEI-BOATENG, C., CRAIG, T., GASHO, C.J., PERRI, M., STAPLETON, R., TSIOROS, S., MINERS, N., TYMKO, M.M., AINSLIE, P.N., Institution: THE UNIVERSITY OF BRITISH COLUMBIA - OKANAGAN, Country: CANADA, Abstract-ID: 364

INTRODUCTION:
Sojourn to high altitude (HA) increases iron demand through hypoxia-induced erythropoiesis. Biological females have higher baseline iron requirements than males and may be more prone to iron deficiency at HA, yet previous studies examining ascent and iron were limited to small female sample sizes and limited temporal measures1. To expand on past findings and assess sex differences in the ∆[ferritin] over 11 days at HA with ad-lib food availability. It was hypothesized that at altitude, ferritin would a) be lower in females across timepoints, b) decrease despite adequate energy and iron intake at the same relative rate between sexes, and c) be inversely related to elevations in hemoglobin.
METHODS:
In 27 (13 females) healthy volunteers, blood samples were obtained at sea-level and on days 3+/-1, 6+/-1, and 11 at HA. Using linear mixed modelling and Pearson’s correlations, we assessed sex differences in the time course of ferritin and hemoglobin at altitude.
RESULTS:
A day*sex interaction (p < 0.01) revealed a steeper slope of ferritin decay in males (β = −3.74 µg/L/day) than females (β = −1.44 µg/L/day). Despite this greater reduction in males, [Ferritin] was consistently 70% lower in females at all timepoints. By day 11 at HA, 6 out of 13 females became iron deficient ([ferritin] < 12µg/L), with no iron deficiency occurring in males. The reductions in [ferritin] at HA were strongly related to elevations in hemoglobin in females (r = −0.79; p < 0.01) but not males (r = 0.28; p = 0.37).
CONCLUSION:
These data indicate that at 3800m, despite ad-lib food availability, females are at a greater risk of iron deficiency, and that [ferritin] is only related to elevations in hemoglobin in females. Iron supplementation should be considered for females traveling and working at HA.

1 Ryan, B. J., Wachsmuth, N. B., Schmidt, W. F., Byrnes, W. C., Julian, C. G., Lovering, A. T., Subudhi, A. W., & Roach, R. C. (2014). AltitudeOmics: Rapid hemoglobin mass alterations with early acclimatization to and de-acclimatization from 5260 m in healthy humans. PloS One, 9(10), e108788. https://doi.org/10.1371/journal.pone.0108788

Funding sources: NSERC and Principal Research Chair to PNA