Changes of diurnal rhythm and levels of total and free testosterone secretion from pre to late puberty in boys: testis size of 3 ml is a transition stage to puberty

Abstract

Objective: To establish levels for comparison for 24-h total and free serum testosterone in prepubertal boys and throughout pubertal development. Design: The study subjects were 55 healthy boys, aged 5.0-18.6 years, who underwent serial sampling one or more times during their pubertal development. Methods: Testicular volumes were determined by orchidometer. Serum testosterone was measured by a modified RIA (detection limit, 0.03 nmol/l). Free testosterone was calculated (calc-FT) using a formula derived from the law of mass action. Results: Significant increases in testosterone and calc-FT concentrations in boys were found between testis volumes of 1 ml to 2 ml, 2 ml to 3 ml, 6 ml to 8 ml, and 10 ml to 15 ml. No differences were found between testis volumes of 3, 4, 5 and 6 ml neither were there differences between 8 and 10 ml, or between 15, 20 and 25 ml. Boys who had reached their final height had higher calc-FT values than boys who had the same pubertal development but had not reached their final height. Based on the results, puberty was classified into six stages: pre1 (testis, 1 ml), pre2 (testis, 2 ml), early (testis, 3 -6 ml), mid (testis, 8-12 ml), late1 (testis,15 -25 ml, not reached final height) and late2 (testis, 15 -25 ml, reached final height). Serum testosterone was secreted with a diurnal variation in prepuberty and during puberty. The increase of testosterone in the morning hours started earlier in pubertal than in pre-pubertal boys. The most pronounced diurnal rhythm was found in early and in mid puberty. Conclusion: Using a sensitive method, and a pubertal reclassification, we have established levels for comparison of testosterone and calc-FT in prepubertal and pubertal boys. The existence of data for comparison forms the basis for future studies on pubertal disorders.

Secondary Sexual Characteristics in Boys: Data From the Pediatric Research in Office Settings Network

“…Largo and Prader' s landmark 1983 14 longitudinal study on white Swiss boys proposed testicular volume of 3 mL as the most accurate sign of central pubertal takeoff based on their earlier work, later confirmed by the Cincinnati 15 and Swedish studies. 16 Boys in the Swiss study were a mean age of 11.2 at genital stage 2 and 11.8 at a testicular volume of 3 mL. The study by Biro et al 15 is the only US puberty study that reported testicular volumes.…”

“…Data on Cincinnati boys 15 and Swedish boys 16 show that the transition from 2 to 3 mL indicates pubertal take-off. White boys in this study reached a mean age of transition to 3 mL at 9.95 years, African American boys at 9.71, and Hispanic boys at 9.63, with no significant difference (P = .11).…”

La pubertad en niños chilenos muestra un adelantamiento en el inicio del crecimiento testicular

“…Por ejemplo en Estados Unidos de Norteamérica (Tabla 3) en población hispánica se encontró una edad de inicio de pubertad de 10 años en varones evaluados por inspección genital 13 y los cambios testiculares fueron más precoces que los observados por inspección. A pesar de lo anterior, esta investigación evaluó crecimiento testicular ≥ a 3 ml, lo que destaca la diferencia de criterios y dificultades en comparar los diferentes estudios 14,15 . Sin embargo, cuando se analizó el aumento de VT ≥ 4 cc esta población mostró el inicio a los 11 años.…”

A purification step prior to commercial sensitive immunoassay is necessary to achieve clinical usefulness when quantifying serum 17β-estradiol in prepubertal children

“…This may be due to potentially interfering substances, particularly cross-reacting water-soluble steroid conjugates, binding proteins (especially SHBG), and non-specific binding (NSB). Concentrations of SHBG are known to be high in prepubertal children (median 92 nmol/l) (12,13) and postmenopausal women (mean 103 nmol/l) (14), and in combination with the 5000-15 000 times lower 17b-estradiol concentrations it is a challenge to quantify accurate concentrations of 17b-estradiol. In this study, we show that the 17b-estradiol calibrators included in the Spectria kit on average contain four times lower SHBG concentrations when compared with that in children's sera.…”