The usefulness of preoperative dual-phase 99mTc MIBI-scintigraphy and IO-PTH assay in the treatment of secondary and tertiary hyperparathyroidism.

Background: Persistent secondary or tertiary hyperparathyroidism (HPT) results from failure to remove enough hyperfunctioning parathyroid tissue. Ectopically situated parathyroid glands and supernumerary glands make failure more likely. Recurrent HPT after subtotal Ptx is usually due to regrowth of the remaining parathyroid tissue. Recurrence may also develop from a hyperplastic supernumerary gland or rarely from parathyromatosis. Recurrent HPT after total Ptx with autotransplantation is usually due to overgrowth of the autograft or for the previously mentioned reasons.

Methods: Since 1995, 464 patients with SHPT or THPT were treated surgically; intraoperative parathormone (PTH) was measured in 277 patients. Sixty-eight patients also had a preoperative MIBI scan. We compared the preoperative MIBI scan results with intraoperative findings, parathyroid gland weight and histology. We questioned whether MIBI uptake corresponded to parathyroid gland size and weight. We also correlated the number of Ki67 nuclear positive cells with MIBI uptake. For SHPT in group I with 145 patients, neither intraoperative PTH (IO-PTH) assay nor MIBI scanning was done. In group II with 163 patients IO-PTH was used and in group III with 48 patients both IO-PTH and MIBI scanning was used. For THPT in group I with 42 patients, neither IO-PTH assay nor MIBI scanning was done. In group II with 46 patients IO-PTH was used and in group III with 20 patients both IO-PTH and MIBI scanning was used.

Results: Parathyroid weight correlated directly with MIBI uptake. No correlation, however, occurred between MIBI uptake and parathyroid histology or between Ki67 staining and MIBI scanning. For SHPT in group I the persistence rate was 6.2% and recurrence rate 11%; in group II the persistence rate was 4.9% and recurrence rate 4.9%; in group III the persistence rate was 2%, and recurrence 4.2% (P < 0.05 between group I and III for persistence and recurrence). We obtained similar results in THPT, but recurrence was 0 in groups II and III, also when only 3 glands were removed, probably due to asymmetric hyperplasia commonly seen in this particular population (P < 0.05 regarding recurrence between group I and II-III, no difference between group II and III).

Conclusion: In conclusion our findings support that the surgeon experience is a very important factor for good results in patients with SHPT and THPT. Preoperative MIBI scanning and IO-PTH are helpful but not essential except in reoperations.