Regarding the laboratory findings, 20/33 (60.6%) patients had hyponatremia (serum Na+<134 mmol/L); the positive rates of LGI1 antibody in blood and CSF were 100% and 93.5%, respectively; and 27/29 (93.1%) patients were LGI1‐positive in both the blood and CSF. Here, LGI1 is linked to Hyponatremia.