A low hemoglobin level may be an indication of anemia, an iron deficiency, or even kidney disease. A high hemoglobin level could indicate lung disease or extreme physical exercise. In a study...

A low hemoglobin level may be an indication of anemia, an iron deficiency, or even kidney disease. A high hemoglobin level could indicate lung disease or extreme physical exercise. In a study conducted by a new testing facility, a random sample of adults was obtained for each combination of sex and altitude. The hemoglobin level (in grams per liter) for each person was recorded.