Endocrine Abstracts

Introduction

The pituitary glycoprotein hormones, luteinizing hormone (LH), follicule-stimulating hormone (FSH), thyroid-stimulating hormone (TSH) and human chorionic gonadotropin (hCG) are comprised of two separate noncovalently bound subunits:alpha and beta units. The alpha subunit is identical in all of the hormones, while the β-subunit is unique for each hormone and confers the specific immunologic and functional activity.Hypersecretion of the glycoprotein alpha subunit has previously been reported in patients with pituitary, with or without concomitant hypersecretion of pituitary hormones.The objective of our work is to describe the variation of alpha subunits according to the anatomopathological aspects of patients with pituitary adenoma.

Material and methods

A retrospective study that focused on the cases of pituitary adenomas, collected at the Endocrinology-Diabetology and Nutrition Department of Mohammed VI University Hospital in Oujda, over a period of 6 years and a half.The data were collected from medical records and the analysis was done by SPSS version 21 software. Sub-unit rate was considered normal between 0.04 and 0.7mUI/ml.

Results

Thirty two percent out of 74 cases of patients with pituitary macro adenoma benefited from pre-operative measurement of alpha sub-units.A low level was found in 12.5% of the patients, whose anatomopathological type was respectively: one case of prolactinoma, one case of non-secreting pituitary adenoma and one patient with a multisecreting pituitary adenoma.Their average age was 31.6 years with a mean subunit rate of 0.03 Mui/ml. This rate was also elevated in 16.7% of cases, varying from 1.5 to more than 10times the normal range, in a patient with gonadotropic adenoma with concomitant elevation of serum FSH and LH gonadotrophins, in a case with non-functional adenoma, a patient with somatotropic adenoma and a patient with somatotropic adenoma. A normal rate was found in the majority of patients, i.e.70.8% of patients mostly women (53%of women) with a mean rate of 0.28mIUi/ml.These cases include:6 patients with prolactinoma, 5cases with non-functional adenoma, 3cases with corticotropic adenoma, 2cases with mixed adenoma secreting both prolactin, LH and GH and one case with somatotropic adenoma.

Conclusion

We conclude that a-subunit hypersecretion may be more common than previously recognized among patients with pituitary tumors. Its high rate may indicate the anatomopathological type of pituitary adenoma, but remains unspecific.The biological and clinical significance of a subunit cosecretion in patients with pituitary tumors is not known at this time.Whether such cosecretion is of importance in the pathogenesis of these tumors or whether it alters the clinical course or response to therapy deserves further study.