Targeted liquid chromatography–tandem mass spectrometry profiling of arginine and histidine derivatives in chronic migraine: Discriminatory performance and changes after onabotulinumtoxinA therapy

OBJECTIVE: This study was conducted to characterize plasma arginine, histidine, 1-methylhistidine, and 3-methylhistidine in chronic migraine and to evaluate their discriminatory ability and association with early clinical response to onabotulinumtoxinA (BoNT-A). BACKGROUND: Alterations in nitric oxide- and histamine-related metabolic pathways may contribute to chronic migraine biology and may provide circulating biomarkers for disease stratification and treatment monitoring. Targeted liquid chromatography-tandem mass spectrometry profiling enables precise quantification of candidate amino acids and derivatives implicated in these pathways. METHODS: This retrospective secondary analysis was conducted as a case-control study with an embedded uncontrolled pre-post analysis and included 30 adults with chronic migraine receiving BoNT-A and 30 age- and sex-matched healthy controls from Istanbul Atlas University Hospital, based on clinical and laboratory data collected between May 15, 2023, and December 15, 2024. Plasma arginine, histidine, 1-methylhistidine, and 3-methylhistidine were quantified by liquid chromatography-tandem mass spectrometry. In the chronic migraine group, pain intensity (visual analog scale [VAS]) and monthly migraine attack frequency were assessed at baseline and 1 month after BoNT-A. Between-group comparisons and within-subject pre-post comparisons were performed, and exploratory analyses evaluated relationships between metabolite levels and clinical outcomes. RESULTS: At baseline, compared with controls, patients with chronic migraine had higher plasma arginine (57.3 ± 13.8 vs. 35.9 ± 10.1 μmol/L; p < 0.001) and 3-methylhistidine (1.0 ± 0.4 vs. 0.7 ± 0.4 μmol/L; p = 0.004), and lower histidine (51.7 ± 10.2 vs. 61.5 ± 6.8 μmol/L; p < 0.001); 1-methylhistidine did not differ significantly (p = 0.217). After BoNT-A, median VAS decreased from 8.0 (7.0-9.0) to 2.0 (0.0-3.0) (p < 0.001) and median monthly migraine attack frequency decreased from 11.0 (6.0-14.8) to 1.0 (0.0-1.8) (p < 0.001). Histidine increased from 54.10 μmol/L (45.27-59.81) to 60.23 μmol/L (57.87-64.45); p = 0.003) whereas 3-methylhistidine decreased from 0.85 μmol/L (0.69-1.23) to 0.66 μmol/L (0.59-0.83); p < 0.001). 1-Methylhistidine did not change significantly, with median values of 5.39 μmol/L (3.41-14.28) at baseline and 6.84 μmol/L (3.36-15.33) at month 1 (p = 0.658). Arginine also did not change significantly with median values of 56.74 μmol/L (46.56-65.95) at baseline and 52.83 μmol/L (44.22-66.30) at month 1 (p = 0.248). Change in histidine was not associated with ΔVAS, and exploratory regression analyses did not identify a robust independent association between baseline variables and pain reduction. In receiver operating characteristic analyses, histidine (area under the curve [AUC] = 0.79) and 3-methylhistidine (AUC = 0.71) showed moderate discrimination, whereas arginine showed higher apparent discrimination (AUC = 0.91). An exploratory combined biomarker model incorporating arginine, histidine, and 3-methylhistidine showed higher apparent discrimination (AUC = 0.94; leave-one-out cross-validated AUC = 0.92). CONCLUSION: Chronic migraine is associated with an arginine-histidine metabolic signature characterized by elevated arginine and 3-methylhistidine and reduced histidine. Early response to BoNT-A is accompanied by substantial clinical improvement and selective modulation of histidine-related metabolites. Histidine and 3-methylhistidine may have value as candidate biomarkers within a broader chronic migraine stratification framework, warranting validation in larger prospective cohorts.