Daily variations in urinary excretion of luteinizing hormone and follicle stimulating hormone in idiopathic isosexual precocity.

The 24-hour urinary excretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH) was determined for 30 days in an 8.3-year-old girl with isosexual precocity and for 25 days in a normal 11.9-year-old girl. The pattern of daily variation in urinary LH and FSH excretion observed in the girl with sexual precocity was similar to that of the normal menstrual cycle. The LH and FSH midcycle peaks were 132.5 IU/24 hours and 26.3 IU/24 hours, respectively. Excluding the midcycle peak, the daily excretion of LH was 28.4 +/- 9.3 (SD) IU/24 hours, and the excretion of FSH was 8.9 +/- 1.9 (SD) IU/24 hours, values comparable to those of normal adult females. In contrast, the daily excretion of LH in the normal 11.9-year-old girl was 6.9 +/- 1.1 (SD) IU/24 hours and FSH excretion was 3.9 +/- 0.9 (SD) IU/24 hours. No LH or FSH surge was observed. The data are consistent with early maturation of the hypothalamic-pituitary-gonadal axis in idiopathic isosexual precocity.