Testosterone trajectories and reference ranges in a large longitudinal sample of male adolescents

Abstract

Purpose: Pubertal dynamics plays an important role in physical and psychological development of children and adolescents. We aim to provide reference ranges of plasma testosterone in a large longitudinal sample. Furthermore, we describe a measure of testosterone trajectories during adolescence that can be used in future investigations of development.

Methods: We carried out longitudinal measurements of plasma testosterone in 2,216 samples obtained from 513 males (9 to 17 years of age) from the Avon Longitudinal Study of Parents and Children. We used integration of a model fitted to each participant's testosterone trajectory to calculate a measure of average exposure to testosterone over adolescence. We pooled these data with corresponding values reported in the literature to provide a reference range of testosterone levels in males between the ages of 6 and 19 years.

Results: The average values of total testosterone in the ALSPAC sample range from 0.82 nmol/L (Standard Deviation [SD]: 0.09) at 9 years of age to 16.5 (SD: 2.65) nmol/L at 17 years of age; these values are congruent with other reports in the literature. The average exposure to testosterone is associated with different features of testosterone trajectories such as Peak Testosterone Change, Age at Peak Testosterone Change, and Testosterone at 17 years of age as well as the timing of the growth spurt during puberty.

Conclusions: The average exposure to testosterone is a useful measure for future investigations using testosterone trajectories to examine pubertal dynamics.

Figure 1. Correlates of the average testosterone exposure.

Average testosterone exposure is inversely related to (A) timing of growth spurt and (B) timing of the largest testosterone increase, but is positively related to (C) magnitude of the largest testosterone increase and (D) total testosterone at 17 years.

Figure 2. Testosterone trajectories by quintiles of the average testosterone exposure.

Higher (Quintile 5) versus lower (Quintile 1) average exposure to testosterone is associated with (A) earlier rising testosterone trajectories that remain relatively high, and (B) earlier onset and greater magnitude of peak change in testosterone. Trajectories are plotted with adjusted testosterone values (see Methods).

Figure 3. Testosterone trajectories by quintiles of the growth-spurt timing.

Earlier (Quintile 1) versus late (Quintile 5) growth spurt is associated with (A) earlier rising testosterone trajectories, and (B) earlier onset of peak change in testosterone. Trajectories are plotted with adjusted testosterone values (see Methods).