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.
OBJECTIVE
To establish levels for comparison for 24-h total and free serum testosterone in prepubertal boys and throughout pubertal development.


METHODS
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.


CONCLUSIONS
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.
Ankarberg-Lindgren
Carina
C
Göteborg Pediatric Growth Research Center, Institute for the Health of Women and Children, The Sahlgrenska Academy at Göteborg University, Göteborg, Sweden. carina.ankarberg-lindgren@vgregion.se
Norjavaara
Ensio
E
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002940:Circadian Rhythm / Q000502:physiology*; D019314:Dehydroepiandrosterone Sulfate / Q000097:blood; D006197:Hair / Q000254:growth & development; D006801:Humans; D008297:Male; D011627:Puberty / Q000502:physiology*; D011863:Radioimmunoassay; D012016:Reference Values; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013737:Testis / Q000033:anatomy & histology* / Q000254:growth & development*; D013739:Testosterone / Q000097:blood / Q000378:metabolism*
D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D019314:Dehydroepiandrosterone Sulfate