TPO and autoimmune disease: Tests for autoimmune diseases and encephalitis, including anti-thyroid peroxidase (TPO) antibody, anti-N-methyl-D-aspartate receptor (NMDAR) antibody, paraneoplastic antibodies, and anti-glutamic acid decarboxylase (GAD) antibody, all showed negative results. CSF analysis revealed a significant increase in protein levels (209 mg/dL), but otherwise, the results were normal (initial pressure, 11.5 cmH2O; cell count, 0/μL; Glu, 116 mg/dL; IgG index, 0.59; CSF cytology, Class I), and phosphorylated tau levels in the CSF were below 25 pg/mL.