Erythropoietin levels in blood donors and patients with anemia, according to hematocrit

This graph shows the inverse linear relationship between hematocrit and erythropoietin levels in 175 individuals (healthy blood donors, denoted by triangles, and patients with various anemias, denoted by squares). Individuals with chronic kidney disease, rheumatoid arthritis, and solid tumors were excluded. The dashed line represents the limit of detection of the assay.