Glycoprotein hormone α‐subunit secretion in prolactinomas and in non‐functioning adenomas: relation with the tumour size

Abstract

Plasma free alpha-subunit levels were increased in 49 of 145 patients (34%). For prolactinomas and 'non-functioning' adenomas, alpha-subunit hypersecretion was seen more often with larger tumours. Half of the cases with increased free alpha-subunit in this series were patients harbouring an adenoma which did not stain for an intact glycoprotein hormone.

Betreuung von Patienten mit hormoninaktiven Adenomen der Hypophyse

“…So fanden sich auch bei 32% der Patienten mit Prolaktinomen erhöhte Konzentrationen der ␣SU [67]. Differentialdiagnostisch kann die ␣SU aber möglicherweise zur Abgrenzung nichtadenomatöser sellä-rer Raumforderungen genutzt werden.…”

Current perspectives on the pathogenesis of clinically non-functioning pituitary tumours

“…They are not, however, accompanied by clinical or biochemical evidence of ACTH excess. Silent somatotroph adenomas have also been described (Warnet et al 1994) and exhibit positive immunostaining for GH, but result in no clinical features of acromegaly. These tumours account for approximately 3% of all NFTs (Kovacs 1985).…”

“…The term non-functioning is strictly a clinical term, as it is now clear from the results of immunohistochemistry that the majority of these tumours do indeed synthesise, and sometimes secrete, hormones (Arafah 1986), predominantly subunits of the glycoprotein hormones (GPHs; luteinizing hormone (LH), follicle-stimulating hormone (FSH) and TSH) or, occasionally, intact GPHs (Snyder et al 1979, Snyder 1985, Black et al 1987, Jameson et al 1987, Klibanski 1987, Warnet et al 1994. Figure 1 shows typical immunostaining properties of an NFT.…”

Evidence for a Trophic Action of the Glycoprotein Hormone α‐Subunit in Rat Pituitary

“…However, part of the a-SU exists in a free form and a-SU can even be expressed without the corresponding P-subunit ( 1 ). This is the case in the pituitary during early embryonic development (2,3 ) and in tumoral cells derived from the gonadotroph lineage in mice ( 4 ) and in humans ( 5 ) as well as in human prolactin (PRL) and growth hormone (GH ) secreting pituitary adenomas (6)(7)(8). These findings suggest a specific biological function for the free U-SU and some experimental data support this view.…”