How do you approach diagnosis and management in patients with persistent hypercalcemia and elevated (but improved) PTH six months after parathyroidectomy for primary hyperparathyroidism?

I believe that what is most important is to rule out familial hypocalciuric hypercalcemia as the likely cause for the persistence of an elevated PTH and persistent hypercalcemia. It is also possible that there is an extraneous parathyroid gland located either near the thymus or in the upper thorax o...