Endocrine studies in primary hypogonadism.

Two 15-year-old boys with primary hypogonadism had evaluation of their hypothalamic-pituitary-gonadal axis. Testicular biopsies and chromsomal studies were also performed. Both patients presented with delayed puberty and short stature and had prepubertal LH, FSH and testosterone concentrations. Serial 24-hour frequent-interval blood studies over a 2-year period in one patient (R.F.) showed a gradual progression from a normal early pubertal LH secretory pattern to one characteristic of 'primary' testicular failure. The testicular biopsies showed prepubertal tests with no significant germinal cell maturation. Although both patients had some somatic stigmata of Noonan's syndrome, they had different karyotypes (XY and xyq-). These studies show that elevated levels of LH and FSH in primary hypogonadism syndrome may not become apparent until after the onset of CNS puberty.