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DISCORDANT SERUM α‐SUBUNIT AND FSH CONCENTRATIONS IN A WOMAN WITH A PITUITARY TUMOUR
Author(s) -
CHAPMAN A. J.,
MACFARLANE I. A.,
SHALET S. M.,
BEARDWELL C. G.,
DUTTON J.,
SUTTON M. L.
Publication year - 1984
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 - 10.1111/j.1365-2265.1984.tb03451.x
Subject(s) - endocrinology , medicine , basal (medicine) , follicle stimulating hormone , protein subunit , pituitary gland , sephadex , bromocriptine , gonadotropin , prolactin , chemistry , hormone , luteinizing hormone , insulin , biochemistry , enzyme , gene
SUMMARY We have studied a women who presented at the age of 51 with a large FSH and a‐subunit producing pituitary adenoma. Following insertion of ventriculo‐peri‐toneal shunts and external pituitary irradiation there was no change in the elevated serum concentrations of FSH, and α‐subunit over a four year period although she developed both ACTH and TSH deficiency. Various drugs, however, did alter the FSH and α‐subunit concentrations and these changes suggest possible mechanisms controlling FSH secretion. Ethinyloestradiol 0.03 mg daily for three weeks suppressed serum FSH to 77% of the basal level (240 ± 35 i.u./l to 184 ±20 i.u./l) but α‐subunit rose to 130% of basal level (281±50 ng/ml to 366±40 ng/ml). On ethinyloestradiol 01 mg daily, FSH suppressed to 17% of basal (40 ±11 i.u./l) with no change in a‐subunit concentration, while on 0.2 mg daily suppression of FSH was similar but α‐subunit fell to 59% of basal (190 ±28 ng/ml). Dexamethasone, 3 mg daily for one week reduced FSH to 53% of the initial concentration and α‐subunit to 74% while bromocriptine 7.5 mg daily for three months, reduced FSH to 39% and α‐subunit to 66% of basal. Neither thyroxine, 0‐2 mg daily for four weeks, nor an LHRH analogue, (Buserelin, Hoechst) 200 μg, three times daily for three months elicited any effect. Chromatography on Sephadex G100 showed that serum FSH and α‐subunit both had K av values somewhat lower than those of their standard counterparts (FSH, 0‐20 vs 0‐25; α‐subunit 0‐35 vs 045). We conclude that the dissociation between changes in FSH and α‐subunit after giving oestrogen, bromocriptine and dexamethasone suggests that these drugs inhibit the synthesis of both a and β‐subunits of FSH with the latter being more sensitive to their effects. The results seem inconsistent with the alternative possibility of impaired release of both subunits or impaired α‐β combination as the mechanism causing the fall in FSH secretion.