Hormonal Changes in Puberty I. Correlation of Serum Luteinizing Hormone and Follicle Stimulating Hormone with Stages of Puberty, Testicular Size, and Bone Age in Normal Boys

Extract: The concentration of luteinizing hormone (LH) and follicle stimulating hormone (FSH) in serum was determind using a double antibody radioimmunoassay method in each of 106 normal boys aged 5-16 years. The boys were grouped according to the stage of puberty (P1-P5) using the classification of TANNER. The serum LH and FSH, LH/FSH ratio, and testicular volume index (TVI) for boys prepuberty (P1) and at different stages of puberty (P2-P5) are shown in figure l and table. The mean value of LH in prepubertal boys was 4.2 ng/ml, which steadily rose to a concentration of 5.3 ng/ml at P4-5. The differences between the values for LH in early puberty (P2) and at a more advanced stage of puberty (P4-5) were statistically significant. The mean value for serum FSH in the prepubertal boy was 1.4 ng/ml. Serum FSH rose steadily through the early stages of puberty (P1-P3) with no further rise from P3 to P4-5. These changes were reflected in the LH/FSH ratio which fel between P1 and P2, but increased between P2 and P4. Tesricular size (TVI) showed a gradual increase from P1 through P4-5. A comparison of serum LH and FSH, LH/FSH ratio. and TVI with chronological age is indicated in table II. A slight increase in the mean levels of serum LH and FSH was observed from age 9 to age 12 with a continued rise to 15 years and older. Serum LH and FSH was obsereved from age 9 to age 12 with a continued rise to 15 years and older. Serum LH seemed to rise at an earlier age than serum FSH. The TVI showed a definite increase from chronologic age 8 through 11. A pronounced change in testicular size from age 11 through 15 was observed during the period of sharp rise in serum FSH. The correlation of bone age with concentrations of LH and FSH in serum, LH/FSH ratio, and TVI is shown in table III. A significant rise in LH was seen in boys with a bone age of 9-10 years, with a further increase at a bone age of 13-15 years and older. Serum FSH showed a steady increment from a bone age of 11 to 14 years. The most pronounced increase in TVI was seen at a bone age of 11 through 15 years. The relation of concerntrations of LH and FSH in serum and LH/FSH ratio to the TVI is presented in table IV. Mean LH and FSH showed a gradual rise from a TVI of <2 to 10.1-12. Serum LH rose and serum FSH fell, however, with the increase in TVI from 10.1-12 to 12.1-16. In four patients with chromatin-positive seminiferous tubular dysgenesis (Klinefelter's syndrome), the mean serum LH concentration was 11.3 ng/ml and the mean serum FSH concerntration was 21.6 ng/ml. The mean serum LH in 14 patients with multiple pituitary hormone deficiencies was 2.1 ng/ml and the mean serum FSH was 1.5 ng/ml. The small diffrences in the concentration of LH and FSH in prepubertal boys compared with that observed in children with hypopituitarism stress the need for further definition of the sensitivity of the assay for serum samples. The serum values reported are of relative not absolute significance. Speculation: The detection of serum FSH and LH prior to puberty, and the increase in serum FSH and LH coincident with advancing puberty suggests 1) that the hypothalamic-pituitary-testicular axis is functional befor puberty, and 2) that the onset of puberry may be associated with a change in sensitivity of the hypothalamus to feedback by testicular steriods.