Reliability of norepinephrine and major monoamine metabolite measurements in CSF of schizophrenic patients.

Concentrations of norepinephrine, 3-methoxy-4-hydroxyphenylglycol, homovanillic acid, and 5-hydroxyindoleacetic acid (5-HIAA) were quantified in the CSF of 28 drug-free schizophrenic patients. Fifteen patients provided more than one drug-free sample on separate occasions. Considerable intraindividual variability over time was found in the concentrations of norepinephrine and these major monoamine metabolites in the repeated samples. This was not explained by assay errors or changes in the patient's global psychosis ratings. The variability in the present sample for CSF 5-HIAA concentrations was almost twice as wide as has been reported for patients with affective disorder. Variables that contribute much of the variability of norepinephrine and major monoamine metabolite concentrations in drug-free CSF samples from schizophrenic patients remain unknown and cannot be controlled.