Nonlocalizing imaging studies for hyperparathyroidism: where to explore first?

For patients with primary hyperparathyroidism (pHPT), imaging studies are obtained to facilitate minimally invasive parathyroidectomy. If imaging studies are nonlocalizing, it is not known if exploration should begin on a particular side or gland location.

A retrospective review of a prospective parathyroid database was performed. The cohort consists of pHPT patients who underwent initial parathyroidectomy between December 1999 and July 2010 and had all preoperative imaging studies reported as nonlocalizing (negative or indeterminate).

Of 880 patients, 151 (17%) had nonlocalizing imaging studies. Reasons for starting exploration on a particular side were identified in 78 (52%) patients and included concomitant thyroid pathology (53%), suspicion on surgeon re-review of imaging (38%), or earlier thyroidectomy (9%). Exploration began on the right in 52%, the left in 42%, and was unknown in 6%. The surgeon had suspicion on imaging in 30 patients and correctly started on the side of pathology in 19 (63%). Hyperfunctioning glands were in eutopic locations in 144 patients (95%) and 3 had intrathyroidal glands. In 111 patients (74%) with single gland disease, median adenoma weight was 320 mg (range 80 to 8,210 mg). There was no difference in adenoma laterality (p = 0.7) or location (p = 0.8). Intraoperative parathyroid hormone criteria were met in 145 (96%) patients and 149 are eucalcemic at last follow-up; 2 (0.7%) patients have persistent disease.

In pHPT patients with nonlocalizing imaging, hyperfunctioning glands are not more frequently located on a particular side or anatomic position. Eutopic location is common and intraoperative parathyroid hormone monitoring should be used to guide the extent of surgery.