1. Danish Headache Center Department of Neurology University of Copenhagen Denmark
2. Danish Knowledge Center on Headache Disorders Rigshospitalet‐Glostrup Denmark
3. Danish Headache Center Glostrup Research Institute Rigshospitalet Glostrup Faculty of Health and Medical Sciences University of Copenhagen Denmark
4. Analytical Chemistry and Neurochemistry Department of Chemistry ‐ BMC Uppsala University Sweden
5. Department of Neurology and MTA‐SZTE Neuroscience Research Group University of Szeged Szeged Hungary