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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Adolescent, Androgens, Aromatase Inhibitors, Child, Double-Blind Method, Drug Therapy, Combination, Erythrocytes, Erythropoiesis, Growth Hormone, Hemoglobins, Humans, Insulin-Like Growth Factor I, Letrozole, Male, Nitriles, Puberty, Puberty, Delayed, Testosterone, Treatment Outcome, Triazoles, Up-Regulation.
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Is pubertal upregulation of erythropoiesis in boys determined primarily by androgen? Context: To study the relative roles of androgens and the growth hormone-insulin-like growth factor I (GH-IGF-I) system in the regulation of erythropoiesis in boys during puberty. We treated 23 boys with constitutional delay of puberty with low-dose testosterone (T), in combination with either a potent aromatase inhibitor, letrozole (Lz; 2.5 mg/d), or placebo (P). The study design was randomized, double-blinded, and placebo-controlled between the treated groups. Treatment with T + Lz was associated with high T and low IGF-I concentrations, whereas treatment with T + P resulted in moderately increased T and high IGF-I concentrations. The blood hemoglobin concentration increased by 1.6 g/dL in T + Lz-treated boys, despite their low IGF-I concentrations. The estimated red blood cell volume increased more in T + Lz-treated than in T + P-treated boys (349 vs 174 mL, respectively, P = .01). Serum T concentrations during the treatment period correlated with the 12-month increments in hemoglobin and red blood cell volume. The changes in blood hemoglobin concentration and RBC in T + Lz-treated boys were similar to those we observed in a population of normal adolescent boys in the late stages of puberty.
assistant
The pubertal increase in hemoglobin concentration in boys is related to direct androgen effects. Final Decision: yes