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Serum α‐subunit levels in patients with pituitary adenomas
Author(s) -
Samejima Naoyuki,
Yamada Shozo,
Takada Koji,
Sano Toshiaki,
Ozawa Yasunori,
Shimizu Taeko,
Usui Masaaki,
Shishiba Yoshimasa
Publication year - 2001
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1046/j.1365-2265.2001.01174.x
Subject(s) - pituitary adenoma , adenoma , medicine , endocrinology , basal (medicine) , pituitary gland , protein subunit , immunohistochemistry , biology , hormone , biochemistry , gene , insulin
OBJECTIVE We investigated preoperative and postoperative serum α‐subunit levels and the α‐subunit response to TRH in patients with various types of pituitary tumour and correlated the data with histological findings in order to clarify the significance of α‐subunit measurement in pituitary adenomas. PATIENTS We examined 59 patients with pituitary tumours (22 with GH cell adenomas, 30 with clinically nonfunctioning adenomas and seven with other tumours) treated at Toranomon Hospital between 1996 and 1998. RESULTS The basal α‐subunit level was supranormal in six out of 22 (27%) patients with a GH cell adenoma and in nine out of 30 (30%) patients with a nonfunctioning adenoma. A paradoxical α‐subunit response to TRH was found in seven out of 22 (32%) patients with a GH cell adenoma. These seven patients also showed a paradoxical GH response to TRH administration. In addition, paradoxical response to TRH was found in eight out of 30 (27%) patients with a clinically nonfunctioning adenoma. In contrast, patients with other types of pituitary tumour showed neither a supranormal α‐subunit level nor a paradoxical response to TRH. The supranormal α‐subunit level and the abnormal response to TRH were normalized in both GH cell adenoma and nonfunctioning adenoma patients after successful surgery. Immunohistochemical studies showed α‐subunit positive cells in 51% of GH cell adenomas or nonfunctioning adenomas and there was a good concordance with the serum α‐subunit levels in both GH cell adenoma and nonfunctioning adenoma patients. CONCLUSIONS These findings suggest that supranormal serum α‐subunit levels are mainly due to hypersecretion by the tumour itself, while the paradoxical α‐subunit response to TRH is an associated phenomenon in patients with a GH cell adenoma or nonfunctioning adenoma. The α‐subunit level and the response to TRH may be useful indicators for assessing the operative outcome, especially in nonfunctioning adenoma patients who have no other definite endocrine markers.