Differences in circulating alpha‐calcitonin gene–related peptide levels in inflammatory bowel disease and its relation to migraine comorbidity: A cross‐sectional study.

Objective: To analyze the specificity of calcitonin gene–related peptide (CGRP) levels, we measured alpha‐CGRP circulating levels in a large series of patients with a recent diagnosis of inflammatory bowel disease (IBD) who were interviewed regarding comorbid headache. Background: Several studies have found an association between migraine and IBD. Methods: In this cross‐sectional study performed in an IBD clinic, morning serum alpha‐CGRP levels were measured by enzyme‐linked immunosorbent assay in 96 patients who were recently diagnosed with IBD and compared to those from 50 similar patients with chronic migraine (CM) and 50 healthy controls (HC). Results: Alpha‐CGRP levels were higher in patients with IBD (median [interquartile range] 56.9 [35.6–73.9] pg/mL) and patients with CM (53.0 [36.7–73.9] pg/mL) compared to HC (37.2 [30.0–51.8] pg/mL; p = 0.003; p = 0.019, respectively). Regarding IBD diagnostic subtypes, alpha‐CGRP levels for ulcerative colitis (67.2 ± 49.3 pg/mL; 57.0 [35.6–73.4] pg/mL) and Crohn's disease (54.9 ± 27.5 pg/mL; 57.7 [29.1–76.1] pg/mL) were significantly higher than those of HC (p = 0.013, p = 0.040, respectively). Alpha‐CGRP levels were further different in patients with IBD with migraine (70.9 [51.8–88.7] pg/mL) compared to HC (p < 0.001), patients with IBD without headache (57.5 [33.3–73.8] pg/mL; p = 0.049), and patients with IBD with tension‐type headache but without migraine (41.7 [28.5–66.9] pg/mL; p = 0.004), though alpha‐CGRP levels in patients with IBD without migraine (53.7 [32.9–73.5] pg/mL) remained different over HC (p = 0.028). Conclusion: Together with CM, circulating alpha‐CGRP levels are different in patients with IBD, perhaps reflecting a chronic inflammatory state. IBD is an example of how alpha‐CGRP levels are not a totally specific migraine biomarker. However, alpha‐CGRP levels were further increased in patients with IBD who have a history of migraine, which reinforces its role as a biomarker in migraine patients, always bearing in mind their comorbidities. Plain Language Summary: Alpha‐calcitonin gene–related peptide (CGRP) levels may be a potential migraine biomarker, but it is unclear if this is the case because changes in CGRP concentrations can also be present in other conditions. We measured morning serum alpha‐CGRP levels in 96 patients with a recent inflammatory bowel disease (IBD) diagnosis, and compared them to 50 matched healthy participants and 50 matched patients with chronic migraine (CM). We found a significant increase in serum alpha‐CGRP levels in both patients with IBD and CM compared to healthy controls, which we think may reflect chronic inflammation found in IBD; these results offer another example that alpha‐CGRP concentrations are not totally specific for migraine. [ABSTRACT FROM AUTHOR]