Estrogen levels in childhood determined by an ultrasensitive recombinant cell bioassay.

Abstract

We hypothesized that estradiol levels are higher in prepubertal girls than in prepubertal boys and that this greater secretion of estradiol might drive the more rapid epiphyseal development and earlier puberty in girls. Since previous estradiol assays have lacked adequate sensitivity to test the hypothesis of higher estradiol levels in girls, we developed a new ultrasensitive assay to measure estrogen levels. The assay uses a strain of Saccharomyces cerevisiae genetically engineered for extreme sensitivity to estrogen. Yeast were transformed with plasmids encoding the human estrogen receptor and an estrogen-responsive promoter fused to the structural gene for f-galactosidase. Ether extracts of 0.8 ml of serum were incubated with yeast for 8 h and the 38-galactosidase response was used to determine estrogen bioactivity relative to estradiol standards prepared in charcoalstripped plasma. The assay was highly specific for estradiol with < 3 % cross-reactivity with estrone, estriol, or estradiol metabolites. The detection limit was < 0.02 pg/ml estradiol equivalents (100-fold lower than existing assays). Using this assay, we measured estrogen levels in 23 prepubertal boys (9.4±2.0 yr) and 21 prepubertal girls (7.7+1.9 [SD] yr). The estrogen level in girls, 0.6+0.6 pg/ml estradiol equivalents, was significantly greater than the level in boys, 0.08+0.2 pg/ml estradiol equivalents (P < 0.05). We conclude that the ultrasensitive recombinant cell bioassay for estrogen is approximately 100-fold more sensitive than previous estradiol assays, that estrogen levels are much lower prepubertally, in both sexes, than reported previously, and that prepubertal girls have 8-fold higher estrogen levels than prepubertal boys. (J. Clin. Invest. 1994Invest. . 94:2475Invest. -2480

Milk consumption and acne in teenaged boys

“…However, recent studies have questioned the methodology and assays on which estimates of daily production rates of endogenous steroid hormones in prepubertal children are based 28 and they suggest that dietary intake may be a more significant source of androgens than previously thought. 29 Milk also contains estrogens, some of which are produced in the lactating bovine mammary gland and are direct suppressors of sebaceous gland function. 30 Milk intake may also affect comedogenicity through the IGF-I pathway, particularly the ability of IGF-I to increase levels of circulating androgens.…”

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

“…Klein and coworkers have developed a RCBA to measure estrogenic activity with a detection limit between 0.07 and 0.7 pmol/l 17b-estradiol equivalents. The sample volume used was 800 ml, the interassay CV was 13% at 7 pmol/l and increased to about 60% at 0.07 pmol/l (19,20). Another RCBA has been developed by Paris et al (21).…”

Oestrogen deficiency in men: where are we today?

“…The long-term goal of therapy should be to use the smallest dose that ensures a physiological bone maturation throughout puberty without interfering with the normal development of secondary sex characteristics, relieves the patient's symptoms, and prevents the early development of osteopenia, a phenomenon that could become one of the major problems in adulthood. We firmly believe that the recent ultrasensitive recombinant cell bioassay for oestradiol (151), which is approximately 100-fold more sensitive than existing assays, will open up new perspectives in the field of oestrogen physiology and subsequently also in the management of congenital oestrogen deficiency.…”