question: 25-year-old female who has had pyruvic kinase enzyme deficiency and macrocytic hemalytic anemia since birth. Hemoglobin levels stay between 6.0 and 8.6 with occasional spikes into 9s. NEVER above the 9 range. Family is planning a vacation in the Colorado mountains. Need to know what is a safe altitude to stay under so as not to cause harm due to thinner air in high altitudes.