Relationship between sestamibi uptake, parathyroid hormone assay, and nuclear morphology in primary hyperparathyroidism

Background Technetium-99m-sestamibi scanning and the intraoperative intact parathyroid hormone (iPTH) assay have permitted development of focused parathyroid techniques for treatment of primary hyperparathyroidism. The purpose of this study was to assess if any pre- and intraoperative factors (degree of sestamibi uptake and iPTH levels) were associated with postoperative results (resected gland weight and parathyroid nuclear morphology). Study design We performed a retrospective analysis of 101 consecutive patients who underwent preoperative sestamibi scintigraphy and a targeted parathyroid exploration for primary hyperparathyroidism. Sestamibi uptake was graded visually on a 4-point scale of 0 (no uptake or false-negative result) to 3 (high uptake) and compared with respect to iPTH levels, gland morphology, and specimen weight. A Kruskal-Wallis test and a Pearson test were used for the statistical analysis. Results Degree of sestamibi uptake was associated with gland weight (median weight of 250 mg, 340 mg, 655 mg, 1,400 mg for grades 0, 1, 2, and 3, respectively, p < 0.001). The uptake of sestamibi was also associated with preoperative PTH levels (median PTH levels of 113, 151, 129, and 170 pg/mL for grades 0, 1, 2, and 3, respectively, p = 0.02), but not with the other parameters. The weight of resected gland(s) was associated with preoperative PTH levels (p = 0.02), and with some of the morphologic nuclear data (mean surface area (p = 0.02), maximum diameter (p = 0.01), and perimeter of the nuclei (p = 0.01). Conclusions These data suggest that false-negative sestamibi scanning (visual score of 0) might result when hypersecreting parathyroid glands are small. Preoperative PTH level might be useful to estimate the amount of hypersecreting tissue to be resected.