Chronobiologic evolution of luteinizing hormone secretion in adolescence: developmental patterns and speculations on the onset of the polycystic ovary syndrome

Abstract

Objective: To investigate the long-term evolution of the LH circadian profile in adolescent women with anovulatory cycles and normal or elevated LH levels in the first evaluation. Design: Prospective controlled clinical study. Setting: Reproductive endocrinology unit of an academic medical center. Patient(s): Twelve healthy anovulatory adolescent girls aged 12 to 17 years (5 subjects with high plasma LH level and 7 subjects with normal LH level) and four ovulatory subjects as controls. Intervention(s): Blood samples were drawn every 20 minutes for 24 hours beginning at 10:00 A.M. at early and late gynecologic ages. Main Outcome Measure(s): Luteinizing hormone, FSH, E 2, T, androstenedione, ovarian volume. Result(s): In the first evaluation, the highest plasma LH levels and greatest pulse amplitude were found early in the morning in the normal-LH group and late in the afternoon in the high-LH group. Controls did not display any significant circadian variation in LH secretion. The second evaluation revealed ovulatory cycles in six of seven subjects (85.7%) in the normal-LH group with the disappearance of the circadian rhythm. Two of five (40%) patients with high LH in the first evaluation became ovulatory with a significant decrease of mean LH levels and the disappearance of the circadian rhythm. Girls of both groups who remained anovulatory still displayed the accentuated circadian profiles that were seen at the first evaluation. Conclusion(s): An accentuated 24-hour LH periodicity is typical of puberty but disappears in adulthood. The persistence of these rhythms in persistently anovulatory adolescents may indicate a maturational arrest. In particular, the persistence of the high LH circadian profile with the highest values during the day is very similar to that found in polycystic ovary syndrome.