PREDICTIVE VALUE OF SERUM FOLLICLE-STIMULATING-HORMONE LEVELS IN THE DIFFERENTIATION BETWEEN HYPOGONADOTROPIC HYPOGONADISM AND CONSTITUTIONAL DELAY OF PUBERTY

Objective: Gonadotropin secretion was evaluated to predict hypogonadot ropic hypogonadism (HH) in 36 children suspected of having HH. Methods : LH was measured for 24 h at 10-min intervals, and FSH and estradiol or testosterone at 1-hour intervals. Twenty boys (age 15.7, range 13.2 -19.3 years) and 16 girls (age 16.1, range 13.0-20.6 years) were studi ed. Results: LH pulses were detected in 9 boys and 5 girls. HH was con firmed in all 11 LH apulsatile boys and in 8 of 11 LH apulsatile girls . Random FSH values of less than or equal to 1.11 and less than or equ al to 2.86 IU/1 in boys and girls, respectively, discriminated patient s with LH pulses from patients without (sensitivity for lack of LH pul ses 97 and 100%, respectively). In boys testicular volume was not disc riminatory. In 1 girl LH pulses were observed without estradiol produc tion, suggesting LH neurosecretory dysfunction. Conclusions: Low FSH l evels in adolescence are strongly related to a lack of LH pulses. Lack of LH pulses is highly suspect for HH. FSH may be a tool in the diffe rentiation between HH and delayed puberty.