A, Hemoglobin in young (left panel) and older (right panel) men during the 20-wk treatment period. Data are mean ± sem. Hg, Hemoglobin. B, Hematocrit in young (left panel) and older (right panel) men during the 20-wk treatment period. Data are mean ± sem. Hct, Hematocrit. C, Mean ± sem percent changes in hemoglobin (Hg) in young (left panel) and older (right panel) men during testosterone treatment. D, Mean ± sem percent changes in hematocrit in young (left panel) and older (right panel) men during testosterone treatment. TE, Testosterone enanthate.