FGF21 and erythema multiforme: For serum FGF-21, the AUC in predicting migraine, EM, CM in all subjects for FGF-21 was 0.729 (sensitivity 59.70%; specificity 87.93%), 0.755 (sensitivity 59.06%, specificity 86.29%), 0.755 (sensitivity 65.79%; specificity 85.60%), respectively.