| Popis: |
Although active gonadotropin-secreting pituitary adenomas are considered very rare, the vast majority of pituitary tumours diagnosed as "non-functioning" express gonadotropins or their free β or α subunits. However, systemic investigations comparing the serum concentrations of follitropin (FSH), lutropin (LH), and α-subunit (αSU) before surgery with the immunoreactivity of the respective substances in the excised tumours are still lacking.Immunostaining of FSH, LH, and αSU was compared in 43 surgically removed gonadotropin - expressing pitu-itary adenomas with serum concentrations of the above-mentioned substances before surgery in the same patients.The serum concentrations of FSH were elevated (11.6 mU/mL) in 8/12 (66.7%) cases of FSH-positive adenomas. By contrast, in FSH-negative tumours the elevation of FSH is absent. Moreover, only 1/25 (4%) patients with LH-positive adenoma had the elevated serum concentration of LH (51.5 mU/mL). The overproduction of LH was not observed in adenomas expressing free β LH or in LH-negative tumours. In patients with αSU-positive adenomas elevated serum levels of αSU were observed in 3/15 (20%) cases. No αSU elevations were observed in patients with αSU-negative adenomas. The mean serum FSH, LH, and αSU concentrations were higher in patients with FSH, LH, and/or αSU immunopositive tumours in comparison with immunonegative. However, the differences are not statistically significant.Although "silent" gonadotropinomas constitute a frequent subtype of pituitary adenomas, the "active" subtype (i.e. manifesting by gonadotropin excess) are rare (approx. 4% of all pituitary adenomas). Gonadotropinomas are difficult to diagnose before surgery. The measurement of gonadotropins including αSU is needed but often not sufficient for presurgical diagnosis. |
