We performed unbiased quantitative mass spectrometry (MS)-based analysis to measure changes in protein abundance and oxidation in cerebrospinal fluid (CSF) from a cohort of Amyotrophic Lateral Sclerosis (ALS) patients and healthy controls at two time points (approximately four months apart) to capture disease progression. In addition, we developed a sensitive and targeted quantitative MS method to measure glutathione oxidation state in the same sets of CSF samples.