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.