Based on the results of genetic and laboratory tests, patients were divided into three groups: those with MEN1 gene mutations (MEN+ group, n=71), those without MEN1 gene mutations — isolated sporadic PHPT (MEN- group, n=158), and patients with PHPT and associated endocrine gland disorders — MEN-1 syndrome phenocopies (PHEN group, n=32). Here, MEN1 is linked to multiple endocrine neoplasia.