We studied the secretion capacity of TSH-β in 63 patients with various pituitary disorders, carrying out the observation of TSH-β changes after TRH administration. Serum TSH-β concentrations were measured by radioimmunoassay according to the modified method of Kourides. Serum TSH concentrations were measured by immunoradiometric assay, and serum concentrations of free thyroid hormones were measured by radioimmunoassay.
Basal TSH-β concentrations were below 0.39 ng/ml in 17 patients with Acromegaly, below 0.56 ng/ml in 5 patients with Prolactinoma, below 0.68 ng/ml in 4 patients with Cushing's disease, below 0.48 ng/ml in 12 patients with non-functioning tumor, below 6.4 ng/ml in 16 patients with SITSH, and below 0.45 ng/ml in 9 patients with other pituitary diseases.
TSH-β changes after TRH administration differed from TSH changes in 4 patients (25%) with Acromegaly, in 2 patients (67%) with Prolactinoma, in 5 patients (71%) with non-functioning tumor, in one patient (33%) with Cushing's disease, in 4 patients (100%) with Rathke's cleft cyst, in one patient with suprasellar meningioma, and in one patient with suprasellar arachinoid cyst.
2 patients (67%) with Prolactinoma, 3 patients (43%) with non-functioning tumor, all 6 patients with non-neoplastic SITSH, and one patient with Rathke's cleft cyst showed exaggerated TSH-β changes after TRH administration.
In patients with some pituitary disorders, we thought the secretion and synthesis of TSH and TSH-β differed from that of normal subjects. We concluded that it was necessary to investigate the mechanism of secretion of TSH-β in patients with pituitary disorders.