Hypopituitarism and idiopathic delayed puberty: a longitudinal study in an attempt to diagnose gonadotropin deficiency before puberty.

Fifty-five hypopituitary patients (43 boys and 12 girls) treated with human GH were studied longitudinally before and during puberty, occurring either spontaneously or induced with testosterone enanthate (100 mg/month, im) in boys and ethinylestradiol (10 micrograms/day, orally) in girls. In addition, 53 boys with idiopathic delayed puberty (IDP) were studied. Gonadotropin integrated responses (IRs) during 90 min after the iv injection of 25 micrograms/m2 LRH, bone ages (BA), and plasma levels of dehydroepiandrosterone sulfate and testosterone were determined at least yearly. Prepubertal hypopituitary patients with gonadotropin deficiency were characterized by: 1) a lowered FSH IR to LRH in most boys and in all girls; 2) a low LH IR for BA; 3) adrenarche either absent or delayed BA; 4) height age close to BA; and 5) the presence of several pituitary deficiencies. In contrast, most prepubertal hypopituitary patients without gonadotropin deficiency showed: 1) a normal FSH IR to LRH; 2) a normal or intermediate (greater than or equal to 75 mIU/ml . 90 min) LH IR for BA; 3) a normal adrenarche for BA; 4) a height age below BA; and 5) isolated GH or GH plus TSH deficiencies. A significant linear correlation was found between LH IR and the logarithm of plasma testosterone. The slopes and levels were similar in controls and hypopituitary boy without gonadotropin deficiency. In IDP, the level was significantly higher. All data obtained in these patients show that the increase in plasma testosterone and the clinical onset of puberty are delayed for the observed pubertal pattern of LH responsiveness. It is concluded that the study of several clinical and biological features, especially the gonadotropin IR to LRH, are of predictive value for the diagnosis of normal or deficient gonadotropic function in prepubertal patients with IDP and hypopituitarism.