Monoamine metabolites in lumbar CSF: the question of their origin in relation to clinical studies

The sources of homovanillic acid (HVA), 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) and 5-hydroxyindoleacetic acid (5HIAA) in lumbar CSF of man are discussed. Although HVA in lumbar CSF is derived from the brain, and MHPG seems to be mainly from the spinal cord, the origin of 5HIAA is uncertain. The evidence for and against a brain contribution to 5HIAA of the lumbar CSF is evaluated. It is concluded that the brain can contribute 5HIAA to lumbar CSF under some circumstances. Measurement of 5HIAA concentrations in lumbar CSF can be of clinical value in detecting changes of 5-hydroxytryptamine (5HT) metabolism in the CNS if the changes are general throughout the CNS.