Idiopathic Hypogonadotrophic Hypogonadal Primary Amenorrhea*

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Abstract
A group of eight patients with idiopathic primary amenorrhea was studied in whom no organic or genetic lesion could be identified. To evaluate the hypothalamic-pituitary axis a sequential stimulation test (SST) was employed using insulin-induced hypoglycemia, followed by a combination of GnRH and TRH with a subsequent dose of GnRH. Three months after the initial SST study, three of the eight patients were then given im injections of 100 µg GnRH daily for 4 consecutive days and the SST was repeated on the fifth day. All eight patients displayed normal GH and cortisol responses. After insulin-induced hypoglycemia, three patients had an absent PRL response and four of the remaining five had a minimal rise. Seven of the eight patients displayed greater PRL responses after TRH administration than was produced by hypoglycemia; however, only one achieved a rise within the range of the normal controls. Seven patients had a lower than normal TSH response to TRH administration, despite having normal serum T4 and T3 levels. Six patients had a blunted LH response after both GnRH stimulations. Four of these six patients had a normal FSH increase to the first dose of GnRH, but all six had a diminished FSH response to the second dose of GnRH. The remaining two patients had normal LH and FSH responses to both GnRH injections. The results of the second SST done in the three patients who were pretreated with GnRH showed a significantly greater LH response (P < 0.005) after the first dose of GnRH, when compared to the pretreatment results. The FSH response did not differ from those observed before GnRH treatment. The findings of a greater response of PRL produced by TRH stimulation than by hypoglycemia and the correction of the diminished LH response to GnRH by repetitive GnRH injections, implies the presence of a hypothalamic derangement in this type of amenorrhea.