Genetic testing is strongly recommended in PHPT patients aged <30 years or when a patient is highly suspected of having syndromic PHPT (multiglandular disease by imaging or history, cooccurrence of other endocrine tumors, atypical parathyroid adenoma and parathyroid carcinoma, familial history of hypercalcemia or syndromic diseases, such as MEN1, MEN2A, MEN4, and HPT-JT) (61). This evidence concerns the gene MEN1 and hypercalcemia disease.