Circadian variations of luteinizing hormone can have two different profiles in adolescent anovulation

The circadian profile of plasma LH concentrations was investigated in 12 healthy anovulatory adolescent women by drawing blood samples every 20 min for 24 h during the early follicular phase. Plasma 17 beta-estradiol, testosterone, and androstenedione levels were measured in the first sample. Ovarian size was measured by ultrasound. According to their mean plasma LH levels, the adolescents were divided into two groups, those with a high plasma LH level (2 Sd or greater than the mean adult value) and those with a normal plasma LH level. The mean plasma estradiol (P less than 0.001) and testosterone (P less than 0.05) levels were higher in the women with high plasma LH levels compared to those in women with normal plasma LH levels. The LH pulse amplitude was greater (P less than 0.05) and the interpulse interval shorter (P less than 0.025) in the high LH group compared to those in the normal LH group. A 24-h periodicity with the highest plasma LH levels and the greatest pulse amplitude in the afternoon was found in high LH group. In the normal LH group, the highest plasma LH levels and greatest pulse amplitude occurred in the first hours of the morning. An accentuated 24-h LH periodicity is typical of puberty, but disappears in adulthood. We have recorded the persistence of pronounced LH circadian changes in anovulatory adolescent women which might be a marker of a continuing maturational process. Furthermore, LH circadian changes have opposing profiles according to the mean LH values, suggesting the presence of different central nervous system pubertal programs.