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- Title
Hypersecretion of the alpha-subunit in clinically non-functioning pituitary adenomas: Diagnostic accuracy is improved by adding alpha-subunit/gonadotropin ratio to levels of alpha-subunit.
- Authors
Andersen M; Ganc-Petersen J; Jørgensen JO; Mellemkjaer S; Petersen PH; Blaabjerg O; Hagen C; Andersen, Marianne; Ganc-Petersen, Joanna; Jørgensen, Jens O L; Mellemkjaer, Søren; Petersen, Per H; Blaabjerg, Ole; Hagen, Claus
- Abstract
<bold>Background: </bold>In vitro, the majority of clinically non-functioning pituitary adenomas (NFPAs) produce gonadotropins or their alpha-subunit; however, in vivo, measurements of alpha-subunit levels may not accurately detect the hypersecretion of the alpha-subunit.<bold>Aim: </bold>We wanted to estimate the reference intervals and decision limits for gonadotropin alpha-subunit, LH and FSH levels, and aratio (alpha-subunit/LH+FSH), especially taking into consideration patient gender and menstrual status. Furthermore, we wanted to examine if the diagnostic utility of alpha-subunit hypersecretion was improved when the alpha-ratios, rather than simply the alpha-subunit levels, were measured in patients with NFPAs.<bold>Material and Methods: </bold>Reference intervals for gonadotropin alpha-subunit serum levels and alpha-ratios were established in 231 healthy adults. The estimated cut-off limits were applied to 37 patients with NFPAs. Gonadotropin alpha-subunit, LH and FSH levels were measured and alpha-ratios were calculated.<bold>Results: </bold>In healthy adults, the cut-offs for alpha-subunit levels were significantly different between men and pre- and postmenopausal women: the cut-offs were 1.10, 0.48 and 3.76 IU/l, respectively. Using these estimated cut-offs, increased alpha-subunit levels were identified in 10 out of 37 (27%) patients with NFPAs. By adding alpha-ratio, in combination with alpha-subunit levels, 23 patients out of 37 (62%) were identified as having elevated alpha-subunit hypersecretion, and 22 out of these 23 patients (96%) had increased alpha-ratios. One premenopausal patient out of 23 had elevated alpha-subunit level but a normal alpha-ratio.<bold>Conclusion: </bold>Our data suggest that adding the simple calculation of alpha-ratio improves the ability of detecting gonadotropin alpha-subunit hypersecretion and thereby indentifying patients with NFPAs.
- Publication
Clinical & Investigative Medicine, 2010, Vol 33, Issue 3, pE203
- ISSN
0147-958X
- Publication type
journal article
- DOI
10.25011/cim.v33i3.13727