Relationship between the circulating levels of adenohypophyseal hormones in blood and in cerebrospinal fluid.

Concentrations of prolactin, follicle stimulating hormone, luteinising hormone and growth hormone were measured simultaneously in the serum and cerebrospinal fluid of 57 patients affected by neurologic disease without any pituitary or diencephalic involvement. Prolactin secretion was stimulated in another group of 12 patients using sulpiride or metoclopramide, and the hormone concentration was measured simultaneously in serum and in CSF during the test. Basal studies showed that the concentrations of prolactin, FSH, LH and GH in serum and in CSF were directly correlated (p varying from less than 0.001 to less than 0.05). A negative correlation was found between the molecular weight of hormones reported in this and in other studies and the natural logarithm of the CSF/serum hormone concentration ratios. During prolactin stimulation the correlation between serum and CSF concentration was maintained, nevertheless a higher increase of prolactin in blood than in CSF was observed. This last finding suggests that other mechanisms in addition to filtration from blood into CSF can be responsible for the presence of adenohypophyseal hormones in CSF.