Plasma concentration of oestradiol-17beta in premature thelarche and in different types of sexual precocity.

Plasma Oe2 concentration was measured by radioimmunoassay in patients with premature thelarche, with precocious puberty and in 29 normal controls. The mean plasma Oe2 was 1.5 pg/ml (0-7.2) in normal prepubertal girls, 23.8 +/- 17.8 (SD) in pubertal girls, 50.2 (+/- 19.4) in the follicular phase, and 94.2 (+/- 19.5) in the luteal phase of normal adult females. Ten girls with premature thelarche had a mean of 7.7 +/- 6.6 pg/ml. Three of them showed higher values than the other 7, suggesting that in these cases, elevated levels of plasma Oe2 might have played a role in the development of breast tissue. Ten untreated girls with idiopathic precocious sexual development had a mean of 51.6 +/- 42.9 pg/ml while 6 patients treated with 150 mg per week of medroxyprogesterone acetate had a mean of 11.4 +/- 2.5 pg/ml. Two patients with Down's syndrome, hypothyroidism and sexual precocity had plasma Oe2 of 144 and 31.5 which fell to 24.7 and 8 pg/ml, respectively, after thyroid replacement. One girl with a granulosa cell tumour had a basal value of 304 pg/ml and a concentration of 27 pg/ml after surgery.