Predictors of an accurate preoperative sestamibi scan for single-gland parathyroid adenomas.

OBJECTIVE: To investigate why some patients with single parathyroid adenomas have negative preoperative sestamibi scans.

DESIGN: Retrospective review.

SETTING: Tertiary care center.

PATIENTS: Twenty-one patients with false-negative (FN) scans were compared with 22 patients with true-positive (TP) scans. All patients had single parathyroid adenomas.

INTERVENTIONS: Neck exploration and removal of parathyroid adenomas.

MAIN OUTCOME MEASURES: Age; sex; preoperative serum calcium and parathyroid hormone levels; gland weight; location; and pathologic features.

RESULTS: There was no significant difference in age or preoperative serum calcium or parathyroid hormone levels. Gland weight was greater in the TP group compared with the FN group (mean +/- SD, 1336 +/- 1603 mg vs 475 +/- 365 mg; P = .04); 13 (62%) of the 21 glands in the FN group were located in the upper position, compared with 6 (27%) of the 22 glands in the TP group (P = .03). Ten of the 22 glands in the TP group consisted predominantly of oxyphil cells, compared with 2 of the 21 glands in the FN group (P = .02). A multivariate logistic regression model yielded the following factors that predicted an accurate scan: higher percentage of oxyphil cells (P = .03), heavier gland (P = .03), female sex (P = .04), and gland location in the lower position (P = .04).

CONCLUSIONS: Smaller-volume parathyroid adenomas and those in the upper position are less likely to be localized with sestamibi scans. A TP scan correlates with oxyphil cell predominance, supporting a role for the mitochondrial-rich cell in sestamibi uptake and retention.