Gonadotropin levels in the cerebrospinal fluid (CSF) as a marker of the gonadotropin secretion from non-functioning pituitary adenomas

ML Gheorghiu; C Badiu; A Caragheorgheopol; D Hortopan; A Dumitrascu; S Galoiu; C Capatana; M Coculescu

P637

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Endocrine Abstracts (2006) 11 P637

ECE2006 Poster Presentations Neuroendocrinology and behaviour (70 abstracts)

Gonadotropin levels in the cerebrospinal fluid (CSF) as a marker of the gonadotropin secretion from non-functioning pituitary adenomas

ML Gheorghiu ¹ , C Badiu ¹ , A Caragheorgheopol ² , D Hortopan ² , A Dumitrascu ² , S Galoiu ¹ , C Capatana ² & M Coculescu ¹

Err

Author affiliations

¹“Carol Davila”, University of Medicine and Pharmacy; “C.I. Parhon”, Institute of Endocrinology, Bucharest, Romania; ²“C.I. Parhon”, Institute of Endocrinology, Bucharest, Romania.

Objectives: Pituitary adenomas usually do not over-secrete gonadotropins in the bloodstream, although they may stain for gonadotropins. Our study aimed to assess whether the pre-operative gonadotropin level in CSF could be used as a marker of the pituitary tumour’s gonadotropin secretion.

Patients and methods: 359 patients with pituitary adenomas, diagnosed between 1979 and 2005 in the Institute of Endocrinology, Bucharest, were evaluated before pituitary surgery with the approval of the local ethical committee: 122 non-functioning pituitary adenomas (NFPA), 132 with acromegaly (ACM) and 105 prolactinomas (PRM). Anterior pituitary hormones simultaneously sampled in serum and CSF were measured by fluorimetric assay (n=359); immunohistochemistry (IHC) was performed by avidin-biotin method (n=71).

Results: While serum and CSF level of GH and prolactin are strongly correlated (r=0.74 and 0.78, respectively) in all pituitary tumours, glycoprotein hormones are not. FSH level in CSF is correlated with LH (r=0.7, P<0.001). CSF and CSF/serum levels of FSH and LH were significantly higher in macroNFPA (mean±standard error: 6.4±1.0 and 4.4±0.7, respectively) than in macroACM (2.6±0.4 and 2.0±0.4) and macroPRM (1.2±0.2 and 1.5±0.2), P≤0.01. FSH levels in CSF were higher in gonadotropin IHC–positive NFPA (19.8±6.2) compared to negative NFPA (3.8±1.0), P<0.01 and to gonadotropin-positive ACM and PRM. FSH in CSF predominated compared to LH in gonadotropin-positive tumours. A CSF FSH value over 5 U/L has 75% sensitivity and 69.2% specificity in identifying a gonadotropin-staining macroNFPA.

Conclusions: FSH level in CSF may be used as a pre-operative marker of the gonadotropin secretion in NFPA, but not in gonadotropin-staining ACM. Predominant FSH secretion in CSF from gonadotropin-staining pituitary tumours suggest a different mechanism for blood-CSF barrier by-passing by glycoprotein hormones compared to peptide pituitary hormones.