GFAP and premenstrual tension: This ratio (Q-GFAP/NfL-CSF) yielded significantly higher values for PMS patients (median: 7.3, 25–75 percentile: 4.8–10.3) compared to RRMS patients (median: 4.8, 25–75 percentile: 1.9–8.3) (p < 0.01) (Fig. 5).