25-Hydroxyvitamin D, 24, 25-dihydroxyvitamin D and 1,25-dihydroxyvitamin D in human cerebrospinal fluid.

Samples of CSF and plasma were obtained simultaneously from 46 adult patients who had no endocrine disorders and were undergoing routine diagnostic lumbar puncture because of suspected or proved prolapse of a disc. Concentrations of 25-OHD, 24,25(OH)2D and 1,25(OH)2D were measured. The samples were purified by column chromatography and fractionated by HPLC. In the appropriate fractions the vitamin D metabolites were measured by PBA, and cytoreceptor assay. The results were as follows (median, range in brackets): 25-OHD in CSF 8.3 ng/ml (2.0-24.8), in plasma 14.5 ng/ml (7.0-36.0). 24,25(OH)2D in CSF 1.8 ng/ml (0.3-4.6) and 2.5 ng/ml (0.4-4.7) in plasma. 1.25(OH)2 D in CSF 25.0 pg/ml (2.2-39.0) and 31.0 pg/ml (10.1-55.0) in plasma. The correlations between plasma and CSF concentrations were as follows: 25-OHD r = 0.479 (P less than 0.001); 24,25(OH)2D r = 0.815 (P less than 0.001) and for 1.25(OH)2D r = 0.497 (P less than 0.001). Our findings showed vitamin D metabolites to be present in human CSF.