Funding: the study was supported by the Nikiforov's All-Russian Center for Emergency and Radiation Medicine, EMERCOM of Russia, within the framework of the research project “Clinical and laboratory diagnosis of chronic urticaria in adults”.

Author contribution: the authors declare compliance of their authorship with the international ICMJE criteria. Mikryukova NV — data acquisition and analysis, manuscript writing; Kalinina NM — editing, introduction of fundamental changes, final approval of the version of the article.

Compliance with ethical standards: the subjects submitted the informed consent to participation in the study approved by the Ethics Committee of the Nikiforov's All-Russian Center for Emergency and Radiation Medicine, EMERCOM of Russia (protocol № 6/21 dated 24 June 2021).