Hormonal changes in puberty. II. Correlation of serum luteinizing hormone and follicle stimulating hormone with stages of puberty and bone age in normal girls.

Abstract

Extract: The concerntration of serum luteinizing hormone (LH) and follicle stimulating hormone (FSH) was determined using a double antibody radioimmunoassay in 129 normal girls. Of theis group, 48 were prepubertal (P1) and 81 girls were at varying stages of pubertal development from P2 to P5. The mean serum LH concentration was similar in the prepubertal (P1) and nonmenstruating girls (P2-4) (3.8—4.2 ng/ml) (table I, fig. 1). A difference was observed in the serum FSH levels that increased steadily from 1.70 ng/ml at P1 to 3.4 ng/ml at stage P8 of puberty. No further change in the concentration of serum FSH was seen in girls P3 to P4. The LH/FSH ratio was lower in girls at P2 than in the prepubertal girls. In the menstruting girls (P5), means concentration of serum LH was within the same range (5.1—4.6 ng/ml) during the three phases of the menstrual cycle. Changes in the concerntration of serum, FSH was observed in menstruating girls: phase I (days 1-12), 3.99 ng/ml; phase II (days 13-18), 3.59 ng/ml; and phase III (days 19-30), 2.51 ng/ml. The relation of the serum LH and FSH levels and LH/FSH ratio to chronologic age was studied (table III). The concerntration of LH was not significantly different in girls 8-12 years. Serum FSH increased from 9 to 13 years. The LH/FSH ratio decreased at 9 years of age with no further change from 10 to 15 years. In addition, serum LH and FSH levels and LH/FSH ratio were compared with bone age (table IV). Serum LH was slightly but significantly less in girls with a bone age of 8 years than in those with a bone age of 6 years. A significant increase in FSH and LH levels was observed in girls with a bone age of 12 years compared with those with a bone age of 8 years. In 14 children with multiple pituitary hormone deficiencies, the serum LH concerntration was 2.2 ng/ml and the serum FSH concentration was 1.5 ng/ml. In 12 patients with XO gonadal dysgenesis of pubertal age, the mean concerntration of serum LH was 11.2 ng/ml and mean concerntration of serum FSH was 54.5 ng/ml. In two patients with XO gonadal dysgenesis, agred 6.5 and 9 years, the serum LH values were 2.5 and 4.5 ng/ml, and the serum FSH values were 1.5 and 2.75 ng/ml, respectively. The serum values descibed are of relative not absolute significance. Although the results indicate that small amounts of gonadotropins are secreted prior to the onset of signs of puberty, it is important to emphasize the necessity of better difinig the lower limits of sensitivity of the assays for serum samples. Speculation: The detection of serum FSH and LH in prepubertal children suggests that the hupothalamic-pituitary gonadal axis is at a low level of activity and already operative at this stage of development. The precise time of initiation of cyclical secretion of LH and FSH (the FSH and LH ovulatory surge) in pubertal girls and its relation to maturational changes in the ovary is not known but it seems likely that the licrease in estrogen secretion by the ovary as puberty advances acts as a positive feedback signal.