Pubertal upregulation of erythropoiesis in boys is determined primarily by androgen

• Published in: The Journal of pediatrics Vol. 146; no. 2; pp. 245 - 252
• Main Authors: Hero, Matti, Wickman, Sanna, Hanhijärvi, Raija, Siimes, Martti A., Dunkel, Leo
• Format: Journal Article
• Language: English
• Published: New York, NY Mosby, Inc 01-02-2005; Elsevier
• Subjects: Adolescent; Androgens - blood; Androgens - metabolism; Androgens - physiology; Aromatase Inhibitors - therapeutic use; Biological and medical sciences; Child; Double-Blind Method; Drug Therapy, Combination; Erythrocytes - drug effects; Erythrocytes - metabolism; Erythropoiesis - drug effects; General aspects; Growth Hormone - metabolism; Hemoglobins - metabolism; Humans; Insulin-Like Growth Factor I - metabolism; Insulin-Like Growth Factor I - physiology; Male; Medical sciences; Nitriles - therapeutic use; Puberty - physiology; Puberty, Delayed - drug therapy; Puberty, Delayed - metabolism; Testosterone - blood; Testosterone - metabolism; Testosterone - therapeutic use; Treatment Outcome; Triazoles - therapeutic use; Up-Regulation; P; GH; MCV; IGF-I; RBC; IGFBP-3; T; STfR; Lz; FAI; Human; Erythropoiesis; Puberty; Pediatrics; Androgen; Hematopoiesis; Male; Sex steroid hormone; Child
• ISSN: 0022-3476; 1097-6833
• DOI: 10.1016/j.jpeds.2004.09.002

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.