Primary hyperparathyroidism results from excess production and secretion of parathyroid hormone from one or more parathyroid glands. Approximately 100,000 new cases are diagnosed each year in the United States. There is an increasing incidence with age. The incidence in the population over 65 is more than 1.5 per 100. Women are affected four times as often as men.

Most cases (approximately 85%) are caused by enlargement of a single parathyroid gland as a parathyroid adenoma. Rarely, hyperparathyroidism may present as part of a familial multiple endocrine syndrome with enlargement of all four glands, or sporadically as parathyroid hyperplasia. Carcinoma of the parathyroid may cause dramatic elevations of the serum calcium but is exceedingly rare.

The classic clinical picture of nephrolithiasis and advanced bone resorption is seen less often now. Most patients present with the identification of an elevated calcium on a routine blood panel, and on closer questioning have only nonspecific symptoms of fatigue, depression and generalized gastrointestinal and musculoskeletal function. Although there is debate about the indications for surgery in these “asymptomatic” patients with mild disease, a recent editorial in the New England Journal of Medicine suggests that nearly all patients with biochemically proven primary hyperthyroidism should be referred for consideration of surgical treatment.

Recent developments in preoperative localization and intraoperative confirmation of successful removal of the criminal gland have made “minimally invasive” parathyroidectomy an option. Tc99m-sestamibi scanning in combination with high resolution ultrasound of the neck allows the localization of the adenoma in 85% of patients preoperatively. In some cases, the uptake of the isotope can be used for a radio-guided approach to identify the adenoma in the operating room. Using a much smaller incision, placed directly over the identified adenoma, the abnormal gland is removed. In appropriate patients, local anesthesia can be used. Approximately ten minutes after removal of the adenoma, an intraoperative parathormone level is drawn. This level can now be determined on an analyzer in the operating suite. Because circulation parathormone has a half-life of approximately 5 minutes, a 50% reduction is anticipated and confirms successful removal of the adenoma. In the 3-5% of patients who have additional hyperfunctioning glands, a persistent elevation of the hormone level requires a more thorough examination with the classic bilateral cervical exploration with visualization of all four parathyroid glands. Patients who have only the “minimally invasive” procedure can usually be discharged home in 2 to 3 hours.

In summary, primary hyperparathyroidism is diagnosed much more commonly than previously thought in our aging patient population. There is evidence that even mildly symptomatic patients may benefit from surgical correction of their disease. Surgical excision of the hyperfunctioning glands offers the only effective means of eliminating the problem. Like many areas of surgery, new techniques allow the use of “minimally invasive” procedures that make the surgical option much more acceptable.

Ref: Utiger RD: Treatment of primary hyperparathyroidism (editorial), N Engl J Med 341:1301, 1999