An ultrasensitive assay revealed age-related changes in serum oestradiol at low concentrations in both sexes from infancy to puberty.
OBJECTIVE
Intensive studies of oestrogen receptors have suggested extragonadal functions of oestrogen. However, the in vivo extragonadal functions of oestradiol remain unclear because of the lack of an adequate assay system at low concentrations. In this study, we assessed the usefulness of a new ultra-sensitive assay for children.


METHODS
Serum oestradiol was measured with an ultrasensitive assay (assayable concentration: 5-1,835 pmol/l: ESTR-US-CT, CIS biointernational, France). Intra- and interassay coefficients of variation at low concentrations (< 36.7 pmol/l) were 8.2 +/- 6.8 (0.1-31.2)% and 8.3 +/- 3.7 (7.5-12.9)%, respectively.


METHODS
Sera from 88 healthy children (55 males and 33 females; 1 month to 16 years old) and 31 patients who underwent gonadal suppression therapy were analysed.


RESULTS
Age-related changes were observed in both sexes. Serum oestradiol concentrations in childhood decreased slightly compared to those in infancy, then increased at puberty. Most prepubertal children showed oestradiol concentrations lower than 36.7 pmol/l. A study on patients who underwent gonadal suppression therapy revealed oestradiol changes within low concentrations, depending on the stage of the therapy.


CONCLUSIONS
The new assay was considered precise enough for the assessment of oestradiol secretion at low concentrations in childhood. Age-related changes in serum oestradiol suggested gonadal activity in the prepubertal period. This assay could be a powerful tool for investigating novel oestradiol functions in vivo.
Ikegami
S
S
Department of Paediatrics, Okayama University Medical School, Japan.
Moriwake
T
T
Tanaka
H
H
Inoue
M
M
Kubo
T
T
Suzuki
S
S
Kanzakili
S
S
Seino
Y
Y
D000293:Adolescent; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D002648:Child; D002675:Child, Preschool; D004958:Estradiol / Q000097:blood*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D007987:Gonadotropin-Releasing Hormone / Q000627:therapeutic use; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D011627:Puberty / Q000097:blood; D011629:Puberty, Precocious / Q000188:drug therapy; D011863:Radioimmunoassay / Q000379:methods; D012016:Reference Values; D012680:Sensitivity and Specificity
D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone