Primary hyperparathyroidism is a disorder involving oversecretion of parathyroid hormone (PTH) from the parathyroid glands resulting in elevated serum calcium, increased calcium extraction from the bone, increased calcium reabsorption in the kidneys, and altered phosphorus metabolism. The majority of cases are caused by a single overactive gland (adenoma), which can be localized by sestamibi nuclear scanning in approximately 80% of adenoma cases. In patients with a single adenoma, 20% or more will result in no abnormal uptake of the sestamibi/technetium study and thus will be classified as “nonlocalizing.” Approximately 15% to 18% of patients with hyperparathyroidism are a result of multiple or all glands being involved in overproduction (hyperplasia) of PTH. While some patients with hyperplasia may erroneously localize on sestamibi, the majority will also result in a nonlocalizing study. Initial exploration may result in successful resolution of the hyperparathyroid state in 70% to 80% of patients in the hands of surgeons who do perform a low volume of parathyroid surgery and up to 95% to 97% of patients in the hands of experienced surgeons using current localizing and intraoperative monitoring techniques. Some patients, however, may require reoperation to control ongoing complications or conditions associated with hyperparathyroidism. Reoperation presents an additional challenge as the scar tissue may hide the abnormal parathyroid tissue and make it more difficult to avoid surgical complications.

Evaluation of the central and lateral compartments of the neck is of paramount importance in the evaluation of patients with hyperparathyroidism. Markedly enlarged thyroid glands and nodules may be a great surgical hindrance at time of parathyroid surgery. All known thyroid nodules 1 to 3 cm should be evaluated with fine needle aspiration biopsy prior to exploration of the parathyroids. Patients with markedly enlarged glands or a substernal goiter should be considered for concomitant thyroidectomy. Vocal fold function should be evaluated and documented in all cases of parathyroid surgery, especially in the setting of reoperative treatment. Paralysis of the vocal fold and palpable parathyroid nodules suggests the presence of parathyroid carcinoma, especially
in the setting of significantly elevated calcium and the absence of a previous history of surgery on the paralyzed side. Approximately 5% of the normal population may exhibit a Chvostek sign despite having normal calcium levels, which would compromise the utility of the test in the postoperative evaluation of calcium levels.

Patients with a history of Roux-en-Y gastric bypass surgery or patients with malabsorption syndromes should be carefully screened for their ability to absorb calcium from the gastrointestinal tract. This may result in an instance of secondary hyperparathyroidism, in which surgery may be detrimental to the patient. Patients failing an oral calcium challenge study should be considered for observation as postoperatively they may require intravenous (IV) calcium as their sole source of calcium.

While initial parathyroid explorations can be done under local anesthesia, the presence of scarring makes this much more difficult in the reoperative setting. Patients who are not fit for general anesthesia should be strongly considered for medical therapy and observation rather than surgery.

The medical records should be obtained from previous thyroid or parathyroid surgery. The pathology and surgical records should be carefully reviewed to determine areas of previous exploration and documentation of previously removed glands. Tissues removed at previous parathyroid surgery should be analyzed by the head and neck pathologist. Preoperative imaging for patients confirmed with the diagnosis of hyperparathyroidism should include a thyroid ultrasound to determine the size of the thyroid lobes and the presence of intra- or extrathyroidal masses, which may represent an enlarged parathyroid gland. Empiric thyroidectomy in the absence of intrathyroidal masses rarely results in resolution of the hyperparathyroid state and can make reexploration more dangerous for recurrent nerve injury. A sestamibi nuclear scan should be obtained to attempt to localize the site of the hyperactive gland. Patients who have previously undergone bilateral exploration should be explored in situations in which the abnormal parathyroid gland can be localized. Hyperactive parathyroid glands that fail to localize on imaging studies and require surgical exploration due to complications of persistent hyperpara thyroidism should be explored in a facility with the capability to perform rapid PTH assay (Table 23.1).