Thiamine deficiency and cerebrospinal fluid 5-hydroxyindoleacetic acid: a preliminary study.

In three out of five patients with low cerebrospinal fluid thiamine concentrations, the 5-hydroxyindoleacetic acid (5HIAA) values also were low. All patients received thiamine replacement therapy; they underwent a second lumbar puncture after 13, 6, 7, 5 and 45 days of treatment. In all patients blood and cerebrospinal fluid thiamine values rose after treatment. In those patients with initially low CSF 5HIAA, thiamine treatment increased 5HIAA markedly.