The Increase in Hemoglobin Concentration With Altitude Differs Between World Regions and Is Less in Children Than in Adults

Heimo Mairbäurl; Samuel Kilian; Svenja Seide; Martina U Muckenthaler; Max Gassmann; Rukundo K Benedict

doi:10.1097/HS9.0000000000000854

The Increase in Hemoglobin Concentration With Altitude Differs Between World Regions and Is Less in Children Than in Adults

Hemasphere. 2023 Apr 5;7(4):e854. doi: 10.1097/HS9.0000000000000854. eCollection 2023 Apr.

Authors

Heimo Mairbäurl^{1

2}, Samuel Kilian³, Svenja Seide³, Martina U Muckenthaler^{2

4}, Max Gassmann^{5

6}, Rukundo K Benedict⁷

Affiliations

¹ Translational Pneumology, University Hospital Heidelberg, Germany.
² Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research, Heidelberg, Germany.
³ Institute of Medical Biometry and Informatics (IMBI), University of Heidelberg, Germany.
⁴ Pediatric Oncology, Hematology & Immunology, University Hospital Heidelberg, Germany.
⁵ Institute of Veterinary Physiology, Vetsuisse Faculty, and Zurich Center for Integrative Human Physiology (ZIHP), University of Zürich, Switzerland.
⁶ Universidad Peruana Cayetano Heredia (UPCH), Lima, Peru.
⁷ ICF, Demographic and Health Surveys (DHS), Rockville, MD, USA.

Abstract

To compensate for decreased oxygen partial pressure, high-altitude residents increase hemoglobin concentrations [Hb]. The elevation varies between world regions, posing problems in defining cutoff values for anemia or polycythemia. The currently used altitude adjustments (World Health Organization [WHO]), however, do not account for regional differences. Data from The Demographic and Health Survey (DHS) Program were analyzed from 32 countries harboring >4% of residents at altitudes above 1000 m. [Hb]-increase, (ΔHb/km altitude) was calculated by linear regression analysis. Tables show 95% reference intervals (RIs) for different altitude ranges, world regions, and age groups. The prevalence of anemia and polycythemia was calculated using regressions in comparison to WHO adjustments. The most pronounced Δ[Hb]/km was found in East Africans and South Americans while [Hb] increased least in South/South-East Asia. In African regions and Middle East, [Hb] was decreased in some altitude regions showing inconsistent changes in different age groups. Of note, in all regions, the Δ[Hb]/km was lower in children than in adults, and in the Middle East, it was even negative. Overall, the Δ[Hb]/km from our analysis differed from the region-independent adjustments currently suggested by the WHO resulting in a lower anemia prevalence at very high altitudes. The distinct patterns of Δ[Hb] with altitude in residents from different world regions imply that one single, region-independent correction factor for altitude is not be applicable for diagnosing abnormal [Hb]. Therefore, we provide regression coefficients and reference-tables that are specific for world regions and altitude ranges to improve diagnosing abnormal [Hb].