Herein, a rare case of PHPT due to ectopic intrathymic parathyroid adenoma was described in an asymptomatic 15-year-old girl who had incidental diagnosis based on laboratory abnormalities but experienced a 3-month postoperative course of persistently elevated parathyroid hormone (PTH) and hypercalcemia following the initial unsuccessful parathyroidectomy operation carried out in a non-parathyroid expert center. Here, PTH is linked to parathyroid gland adenoma.