A Sequential Pituitary Stimulation Test in Normal Subjects and in Patients with Amenorrhea-Galactorrhea with Pituitary Tumors*

Open Access
Publisher Website
Google Scholar
Abstract
A sequential pituitary stimulation test (SST) using insulin induced hypoglycemia followed by the administration of Gn-RH in combination with TRH and then by Gn-RH alone was utilized to study the hypothalamic-pituitary function of a group of 9 normal controls as well as 15 patients with amenorrhea-galactorrhea and pituitary tumors. With the stimulation of hypoglycemia a significant increase of hGH, cortisol and hPRL occurred in all control subjects 1 h after the administration of insulin, without a significant change in the levels of LH, FSH or TSH. Following administration of Gn-RH and TRH a significant rise of LH, FSH, hPRL and TSH was observed in all control subjects. Following the second bolus of Gn-RH a significantly greater increase of both LH and FSH was also observed. Fourteen out of the fifteen patients with pituitary tumors had a hGH response lower than the controls. No increase in cortisol was noted in four patients. Baseline levels of hPRL were all elevated and no increase occurred in thirteen patients. A normal TSH response was observed in all these patients. Following the first Gn-RH administration, thirteen patients had a normal LH response and two had an abnormally low response. In contrast, eight patients had FSH response significantly greater than the controls, four patients had a normal response and three had a lower than normal response. Following the second dose of Gn-RH, six patients had a low LH response and five patients had a low FSH response. The most consistent abnormalities were the abnormal hGH response, elevated baseline hPRL which did not respond to stimulation and a greater than normal response of FSH to Gn-RH. The use of sequential Gn-RH stimulation is useful in demonstrating decreased pituitary residual capacity for gonadotropin secretion.