Mancera E1, Ramos D2, Cristancho E2, Schmidt W3, Medellín JP4, Duque L5, Rojas J5
1Universidad Nacional de Colombia, Bogota, Colombia, 2Universidad Nacional de Colombia, Facultad de Ciencias, Bogota, Colombia, 3Universidad Nacional de Colombia, Sports and Sciences, Bogotá, Colombia, 4Unidad de Ciencias Aplicadas al Deporte (IDRD), Bogota, Colombia, 5Unidad Central del Valle, Bogota, Colombia
Background: In the prepubertal stage, total hemoglobin mass (tHb) is similar in boys and girls. With the beginning of puberty, tHb increases significantly in men, while in women it tends to stabilize. This situation could be explained by the increase in androgen production in men. There is enough evidence that androgenic hormones act as a strong stimulant of erythropoiesis. However, this has not been studied in children and adolescents.
Purpose: To determine whether testosterone is a determinant factor of erythropoiesis and the differences in tHb between men and women during adolescence
Methods: Transversal study. Participants were 313 children and adolescents of both sexes, Tanner I-V on the scale of sexual maturation, trained in endurance sports (T) and untrained controls (UT), residents at two different altitudes: low altitude (LA, 1000 m) and moderate altitude (MA, 2500 -3000 m). Two phases were developed. In the first, comparisons were made between men (n = 123) and women (n = 94). In the second phase, analyses were performed only on a male population (n = 219). Thb, blood volume (BS), erythrocyte volume (EV) and plasma volume (PV) were determined by the optimized CO rebreathing method. Hemoglobin concentration [Hb], hematocrit (Hct), testosterone, ferritin, erythropoietin (EPO) and body composition parameters were measured.
Results: Statistical analysis was carried out through linear regressions and classification and regression trees (CART). The men had 2.31 ng/mL (p 0.001) more of testosterone than the women and the highest values were evidenced from stage III maturation according to the Tanner scale. Testosterone concentration was dependent on the stage of maturation in men. A strong correlation was found between testosterone and tHb (r = 0.8, p 0.001) and between testosterone and tHb relative to body mass (tHb/kg) (r = 0.6, p 0.001) in both men and women. In men, the change of 1 ng/mL in testosterone was associated with an increase of 34.2 g of tHb (p 0.001). THb values greater than 13 g/kg were associated with concentrations of 1.2 ng/mL of testosterone. In MA, high tHb/kg values were associated with a testosterone concentration greater than 4.9 ng/ml. The importance of the effect of testosterone on tHb was 45%, against 34.4% of the effect of biological maturation, 16.0% of training and 5.0% of altitude. A strong correlation of testosterone with EV and BV was found (r = 0.7, p 0.001).
Conclusion(s): Women present low levels of testosterone and in men there is a significant increase from stage III of Tanner, which determines an increase in erythropoiesis. The above explains the differences in tHb, EV and BV between men and women from the beginning of puberty.
The increase in the production of testosterone during adolescence is the mean factor of the increase in tHb, EV and BV in men.
Implications: Our study is the first to analyze the effects of testosterone on tHb in adolescents. Our findings confirm that testosterone is an erythropoietic factor that determines the increase in tHb, therefore this in a determining factor for energy production in endurance exercise in men
Keywords: Testosterone, erytrhopoiesis, hemoglobin mass
Funding acknowledgements: This study was funding by Universidad Nacional de Colombia
Purpose: To determine whether testosterone is a determinant factor of erythropoiesis and the differences in tHb between men and women during adolescence
Methods: Transversal study. Participants were 313 children and adolescents of both sexes, Tanner I-V on the scale of sexual maturation, trained in endurance sports (T) and untrained controls (UT), residents at two different altitudes: low altitude (LA, 1000 m) and moderate altitude (MA, 2500 -3000 m). Two phases were developed. In the first, comparisons were made between men (n = 123) and women (n = 94). In the second phase, analyses were performed only on a male population (n = 219). Thb, blood volume (BS), erythrocyte volume (EV) and plasma volume (PV) were determined by the optimized CO rebreathing method. Hemoglobin concentration [Hb], hematocrit (Hct), testosterone, ferritin, erythropoietin (EPO) and body composition parameters were measured.
Results: Statistical analysis was carried out through linear regressions and classification and regression trees (CART). The men had 2.31 ng/mL (p 0.001) more of testosterone than the women and the highest values were evidenced from stage III maturation according to the Tanner scale. Testosterone concentration was dependent on the stage of maturation in men. A strong correlation was found between testosterone and tHb (r = 0.8, p 0.001) and between testosterone and tHb relative to body mass (tHb/kg) (r = 0.6, p 0.001) in both men and women. In men, the change of 1 ng/mL in testosterone was associated with an increase of 34.2 g of tHb (p 0.001). THb values greater than 13 g/kg were associated with concentrations of 1.2 ng/mL of testosterone. In MA, high tHb/kg values were associated with a testosterone concentration greater than 4.9 ng/ml. The importance of the effect of testosterone on tHb was 45%, against 34.4% of the effect of biological maturation, 16.0% of training and 5.0% of altitude. A strong correlation of testosterone with EV and BV was found (r = 0.7, p 0.001).
Conclusion(s): Women present low levels of testosterone and in men there is a significant increase from stage III of Tanner, which determines an increase in erythropoiesis. The above explains the differences in tHb, EV and BV between men and women from the beginning of puberty.
The increase in the production of testosterone during adolescence is the mean factor of the increase in tHb, EV and BV in men.
Implications: Our study is the first to analyze the effects of testosterone on tHb in adolescents. Our findings confirm that testosterone is an erythropoietic factor that determines the increase in tHb, therefore this in a determining factor for energy production in endurance exercise in men
Keywords: Testosterone, erytrhopoiesis, hemoglobin mass
Funding acknowledgements: This study was funding by Universidad Nacional de Colombia
Topic: Sport & sports injuries; Paediatrics
Ethics approval required: Yes
Institution: Universidad Nacional de Colombia
Ethics committee: Science Faculty
Ethics number: Register 06-15
All authors, affiliations and abstracts have been published as submitted.
