PTH and primary hyperparathyroidism: In fact, although parathyroidectomy (PTx) is successfully in 90% of cases of primary hyperparathyroidism (HPT1), in 10% the calcemia and PTH values return or become elevated as a result of an unidentified or inaccessible adenoma, multiglandular disease, insufficient excision of hyperplastic glands, difficulty in distinguishing between adenomatous tissue and hyperplastic gland3.