Measurement of Neuro-Transmitter Metabolites in Blood, Urine and CSF in Psychiatric Patients

Abstract

Publisher Summary This chapter discusses the measurement of neurotransmitter metabolites in blood, urine, and cerebrospinal fluid (CSF) in psychiatric patients. Various lines of evidence suggest that 3-methoxy-4-hydroxyphenylglycol (MHPG) is the major metabolite of noradrenaline in the central nervous system (CNS) of various animals and in man. Free and conjugated MHPG have been demonstrated in CSF. CSF levels of MHPG are determined by the rate of efflux of MHPG from the CSF, which is not effectively blocked by probenecid in humans. Various studies have shown that in the CNS, MHPG is continuously lost through capillaries within tissue, and thus, only a portion of the MHPG that is produced ever reaches the CSF. It has also been demonstrated that MHPG in lumbar CSF reflects noradrenaline metabolism in spinal cord and in brain. Some studies of lumbar CSF MHPG levels report lower levels in depressed patients as compared to controls, but not all studies agree. In one study, MHPG levels were not different from control values in depressed patients, but manic patients showed markedly elevated levels of MHPG with a decrease to normal values during successful treatment with lithium.