Yes—among 45 healthy men, living at 2,270 meters was linked to blood changes, including more even red cell sizes. One change involved RDW (Red Cell Distribution Width). This measures how much red blood cells differ in size. It fell during the study, meaning those cells became more alike in size. The source summary does not report the size of that drop. The study followed healthy male students from West Africa for six months. They had moved from sea level to southwestern Saudi Arabia. Blood tests were taken within 48 hours of arrival. Tests were repeated at two months and six months. So, these findings cover months at altitude, not a weekend trip. RBC (Red Blood Cells) counts rose at both follow-up tests. So did Hemoglobin, the protein that carries oxygen. Hematocrit, the share of blood made up of red cells, also increased. Together, these changes suggest the body was adjusting to less oxygen at altitude. A lower result does not, by itself, prove better health. This small study only included healthy men. It did not establish whether these blood changes improved health. The authors also noted that altitude may matter when setting usual blood test ranges. For BioSocial members, location adds useful context to a bloodwork timeline. Recording elevation and time since a move could help explain changing numbers. Comparing notes with the community may be more useful when those details match. It also helps separate a months-long stay from a brief visit. What changes have you noticed in your blood test numbers after spending time at a different altitude?