Impaired prolactin response to thyrotropin-releasing hormone in isolated gonadotropin deficiency and exaggerated response in primary testicular failure.
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Biomedical subjects
Publications and source records attributed to U Almaliach.
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A 17 year old male patient presented with short stature and delayed puberty. Investigations showed normal thyroid function and intact TSH response to TSH-releasing hormone (TRH). Although basal levels of LH were low, both LH and FSH rose following the administration of LH-releasing hormone (LHRH). ACTH secretion assessed indirectly by the cortisol response to insulin hypoglycemia was normal. Growth hormone levels increased following the onset of sleep, as well as after the administration of insulin, L-dopa and L-arginine. Basal levels of prolactin were low (2-5 ng/ml) compared with 5-12 ng/ml in controls. There was a markedly impaired prolactin response to TRH (maximum rise above basal values of 3 ng/ml compared to a rise of 12-29 ng/ml in controls). Prolactin levels did not rise after the administration of chlorpromazine or L-arginine. There was some suppression of prolactin levels after L-dopa. Similar patterns of prolactin are seen in panhypopituitarism, where they are usually associated with other hypophyseal hormonal deficiencies. The diminished prolactin reserve demonstrated in this subject in the presence of intact function of the remainder of the anterior pituitary is compatible with the diagnosis of diminished prolactin reserve.
The hormonal response to luteinizing hormone releasing hormone (LHRH) thyrotropin releasing hormone (TRH) and chlorpromazine has been evaluated in eleven female subjects with the syndrome of isolated bihormonal gonadotropin deficiency (IGD). Following LHRH, all subjects had elevations of both LH and FSH, but the gonadotropin responses were attenuated relative to those observed in normal female subjects studied in the early proliferative phase of the cycle. Similarly, peak TSH levels after TRH were significantly less in subjects with IGD relative to normal controls. Basal prolactin levels were low in the patient group. Prolactin levels following TRH increased at least two-fold in control subjects and in the group with IGD. Conversely, chlorpromazine failed to induce elevations of prolactin in eight of nine females with IGD.