NPPA and myeloid sarcoma: The results of metabolic profiling of MS patients show that the KYNA/QA ratio is able to determine the excitotoxic activity of KP and may represent a predictive model for MS subtype progression by assessing the levels of six possible predictive characteristic biomarkers of the disease: KYNA, QA, tryptophan, picolinic acid, fibroblast growth factor, and TNF-α (in order of relevance) with a sensitivity of up to 85–91%.