Gonadotropin responsiveness to luteinizing hormone releasing hormone in prepubertal and pubertal patients with growth hormone deficiency.

Gonadotropin response to 100 microgram/m2 LHRH was determined in 31 patients with growth hormone deficiency. According to their bone ages the patients were divided into a "prepubertal" (n = 18) and a "pubertal" (n = 13) group. The results were compared with the LHRH tests from 16 healthy prepubertal boys and girls and 32 healthy adult probands, respectively. The maximum increment of LH and FSH was evaluated. In the "prepubertal" group five patients had an insufficient rise of LH and FSH, four of them having additional anterior pituitary hormone deficiencies. In the "pubertal" group nine patients were found to be gonadotropin deficient, all of them had additional hormone deficiencies, TSH being the most frequently affected hormone. Only one of 14 gonadotropin-deficient patients had no other than growth hormone deficiency in addition. An isolated decreased FSH increment without LH deficiency was found in 6 male and 2 female patients and is not thought to be of diagnostic value. No influence of growth hormone treatment or growth velocity on the gonadotropin responsiveness was found. Patients with an additional thyreotropic defect could be classified as pituitary or hypothalamic disorder due to their reaction in the TRH test. These groups could not be differentiated by a single bolus LHRH test, indicating the need of prolonged stimulation to recover the pituitary hyporesponsiveness. Due to methodological problems the diagnosis of gonadotropin deficiency in an individual patient of the prepubertal age group might be questioned. However, a normal gonadotropin response to LHRH can be expected in prepubertal patients with growth hormone deficiency and may indicate a normal gonadotropin function.