Portal de Periódicos da CAPES

Pubertal upregulation of erythropoiesis in boys is determined primarily by androgen

2005; Elsevier BV; Volume: 146; Issue: 2 Linguagem: Inglês

10.1016/j.jpeds.2004.09.002

1097-6833

Matti Hero, Sanna Wickman, Raija Hanhijärvi, Martti A. Siimes, Leo Dunkel,

Sexual Differentiation and Disorders

Objectives 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. Study design 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. Results 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. Conclusions The pubertal increase in hemoglobin concentration in boys is related to direct androgen effects. 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. The pubertal increase in hemoglobin concentration in boys is related to direct androgen effects.