Plasma changes of calcitonin gene-related peptide and substance P in patients with dialysis headache.

Little is known of mechanism of dialysis headache (DH). As suggested for migraine, a role for neuropeptides has been investigated. Twenty-four patients under haemodialysis were studied. Twelve of them suffered from DH. The remaining patients were headache free. Blood samples for radioimmunoassay of calcitonin gene-related peptide (CGRP) and substance P (SP) were collected from the arteriovenous fistula before and after dialysis treatment. Basal plasma concentrations of CGRP were found to be higher in headache patients. Dialysis significantly decreased CGRP concentrations in both groups. No difference in basal plasma concentrations of SP was observed between groups. At the end of the treatment plasma SP concentrations were reduced in headache-free patients but increased in headache patients. Elevated plasma concentrations of CGRP in patients with DH could represent a biochemical factor contributing to susceptibility to headache. Because of the disputable role of SP in migraine, the significance of the increase of the peptide in plasma during DH remains to be elucidated.