PITUITARY HORMONES IN HUMAN CEREBROSPINAL FLUID.

Introduction. The blood brain barrier (BBB) restricts the transport of hydrophilic molecules such as peptidic pituitary hormones into the brain tissue. The blood-cerebrospinal fluid (CSF) is a part of the BBB. Aim To compare the pituitary hormone levels on the two sides of the BBB in a group of subjects without endocrine diseases. Patients and methods. We investigated, with the approval of the local ethics committee, 78 subjects without endocrine diseases. Growth hormone (GH), prolactin (PRL), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and thyroid stimulating hormone (TSH) were measured by rapid fluoroimmunoassay with Europium in the blood and cerebrospinal fluid (CSF) sampled simultaneously before rachianestesia for minor surgery. Results. CSF concentrations are significantly lower than the corresponding serum ones for all hormones studied: 0.04 ± 0.009 mU/mL vs 2.29 ± 0.57 mU/mL for GH, 1.49 ± 0.078 ng/mL vs 10.07 ± 1.42 ng/mL for PRL, 0.57 ± 0.078 U/L vs 22.71 ± 3.65 U/L for FSH, 0.39 ± 0.038 U/L vs 11.11 ± 1.55 U/L for LH and 0.01 ± 0.003 μU/mL vs 1.36 ± 0.17μU/mL for TSH (mean ± SEM; p<0.001). The CSF/serum ratio was below 1 in the vast majority of cases (from all subjects studied we only found 3 cases with supraunitary CSF/serum ratio). The serum and CSF levels were not significantly correlated for any of the pituitary hormones. Comparing preand postmenopausal women the CSF gonadotropin levels were slightly but nonsignificantly increased after menopause, despite marked differences in the serum concentrations: CSF FSH 1.21 ±0.17U/L after vs 0.84± 0.4U/L before menopause, CSF LH 0.60± 0.047U/L after vs 0.43± 0.14U/L before menopause. The CSF/ serum ratio for FSH markedly decreased after menopause (0.02±0.003 vs 0.22±0.11) although the effect did not reach statistical significance. The same was true for CSF/serum LH ratio (0.026±0.005 vs 0.09±0.002). For none of the hormones studied the CSF levels correlated with age. Conclusion. Pituitary hormones are normally found in the CSF at much lower levels than in the serum. The CSF hormonal concentrations do not significantly correlate with the serum ones. [ABSTRACT FROM AUTHOR]