High level of pyridoxal 5'-phosphate in the cerebrospinal fluid of adult celiac patients.

Adults with intestinal malabsorption due to celiac disease show reduced central serotonin metabolism, probably induced by a lack of essential dietary factors. Investigating a role proposed for vitamin B6 deficiency, a regular finding in untreated celiacs, the present study yields no support for the hypothesis that direct inhibition at the decarboxylation step by vitamin B6 deficiency accounts for low central serotonin turnover in adult celiacs: 11 untreated patients showing reduced 5-HIAA in the cerebrospinal fluid (71+/- 26.8 pmol/ml) had a significantly higher concentration of the metabolically active B6 vitamer pyridoxal 5'-phosphate in lumbar cerebrospinal fluid (0.06 +/- 0.34 ng/ml) than controls (0.24 +/- 0.07 ng/ml) (p less than 0.01). Cerebrospinal fluid tryptophan, precursor of serotonin, was normal (2035 %/- 649 pmol/ml). Raised pyridoxal 5'-phosphate in the cerebrospinal fluid in untreated celiac disease is an unexpected finding. Possibly it is secondary to the diminished central monamine metabolism in these patients, but further studies are needed bearing in mind that mental depression is a major cause for disability in adult celiac disease.