Risk factors for "PTH spikes" during surgery for primary hyperparathyroidism.

PURPOSE: Increased intraoperative parathyroid hormone excretion ("PTH spikes") due to unintended manipulation of parathyroid adenoma can be observed frequently during surgery for primary hyperparathyroidism. This may lead to difficulties in interpreting intraoperative PTH curves. The aim of this study was to elucidate possible risk factors for PTH spikes and to evaluate the impact on different interpretation criteria of intraoperative PTH curves.

METHODS: Eight hundred forty-seven patients with primary hyperparathyroidism were included. The probability of PTH spikes was analyzed regarding preoperative PTH- and creatinine levels, and size of adenoma and their impact on the Vienna, Miami, and Halle criteria was evaluated.

RESULTS: PTH spikes occurred in 102 patients (12 %) and revealed to be independent of PTH- and creatinine levels (p = 0.13) preoperatively. There was a significant negative correlation between "manipulation PTH" and "baseline PTH" values and the gland volume, respectively. Patients presenting with smaller adenomas and those with low-baseline PTH values show significantly higher manipulation values. No risk factor for manipulation was exposed and no significantly higher risk of misclassification as "false positive" in case of PTH spikes was detected for any interpretation criterion. For the "Vienna Criterion," however, a significant increase in the risk of "false negative" misclassification was observed with increasing manipulation values.

CONCLUSIONS: In patients with PTH spikes, none of the analyzed criteria show a significant increase in missed adenomas. Nevertheless, the Vienna criterion shows a higher rate of potentially unnecessary explorations with increasing manipulation values. Thus, caution is warranted in detecting PTH spikes and in individual interpretations of specific PTH curves is recommended. The Miami criterion seems to be favorable in this group of patients.