Introduction: The concentrations of pituitary hormones in the cerebrospinal fluid (CSF) are much lower that their serum counterpart.
Aim: To study the CSF access for pituitary glycoprotein hormones (GPH) in patients with pituitary adenomas (PA).
Patients and methods: In 221 cases submitted to transsphenoidal surgery for PA (85 acromegaly ACM, 92 nonfunctioning pituitary adenomas NFA, 44 prolactinomas PRM) the surgical specimen was immunostained for expression of FSH, LH and TSH using avidinbiotin technique. In these patients (221) and a control group without endocrine diseases (79), in serum and CSF simultaneously sampled, the FSH, LH and TSH were assayed by fluoroimmunoassay with europium.
Results: In all types of pituitary tumors the mean CSF levels of GPH, i.e. (FSH 3.4±0.56 IU/l, LH 1.94±0.28 IU/l and TSH 1.78 mU/l±0.47) were much higher than in the control group: 0.56±0.08, 0.39±0.03, 0.01±0.03 respectively (P<0.05). The serum levels do not follow this pattern.
The tumors with positive immunostaining for FSH (12.21%), LH (9.5%), TSH (4.5%) do not influence more the CSF levels, but the size of the tumor does (mean diameters 30.4 mm±0.17 NFA, 28.1 mm±0.23 PRM, 19.9 mm±0.13 ACM). The intrasellar tumors (n=41), without contact to the CSF, showed greater CSF hormone levels than controls, but less than suprasellar expanded tumors (SSE n=123). The SSE are larger. They showed contact with the CSF space but even in that group the GPH-immunopositive tumors were not associated with higher CSF levels than GPH-immunonegative ones. This suggests that glycoprotein hormones, that originate in pituitary cells, are not directly released into the CSF, but, probably, through local blood vessels.
Conclusion: In conclusion, in the presence of pituitary adenomas, pituitary glycoprotein hormones (from tumor or normal pituitary cells) pass easier in the CSF. Very probably the retrograde blood flow of the portal vessel system is influenced by the tumor size.
30 Apr - 04 May 2011
European Society of Endocrinology