Primary hyperparathyroidism Nature reviews endocrinology Vol 14, 2018. 2 Epidemiology and pathogenesis PHPT is caused by a solitary parathyroid adenoma in 80% of cases, whereas four-gland hyperplasia accounts for 10–15%, multiple denomas for 5% and parathyroid cancer for 80%) of patients with PHPT in the USA and Western Europe are ‘asymptomatic’,a term used to describe those lacking the skeletal..