Serum and cerebrospinal fluid biochemical markers of ALS.

To date there is no satisfactory serum or cerebrospinal fluid (CSF) metabolic marker with which to identify patients with ALS. The goal of finding a suitable marker will be more feasible following the identification of defined subgroups of patients with ALS. Some aspects of neurotransmitter chemistry in CSF seem worthy of further investigation, in particular, clarification of whether there is a significant elevation of CSF glutamate in a subgroup of patients and whether there are robust alterations in the noradrenaline transmitter system. It seems unlikely, in the face of present evidence, that the presence of aberrant exitatory amino acid transporter 2 transcripts in CSF will prove to be a useful marker of ALS. Increased levels of 3-nitrotyrosine and neurofilament light in CSF, while not entirely disease-specific for ALS, may nevertheless prove useful confirmatory markers of the disease and its progression.