The number of needle passes affects the accuracy of parathyroid hormone assay with intraoperative parathyroid aspiration.

INTRODUCTION

Intraoperative aspiration of a nodule and parathyroid hormone (PTH) assay has been shown to accurately confirm parathyroid tissue. However, the reported aspiration technique varies in the literature. We sought to determine if the number of passes affected the accuracy of PTH analysis.

METHODS

A prospective analysis was performed on 25 consecutive patients who underwent a parathyroidectomy for primary hyperparathyroidism. The excised parathyroid gland was aspirated using 1, 3, and 5 passes. The data were analyzed using the Wilcoxon rank, chi-square, and Fisher exact tests to calculate the 2-tailed P value.

RESULTS

Of the 26 glands aspirated, the mean PTH value varied with the number of passes, 2,073 pg/mL for 1 pass, 2,347 for 3 passes, and 2,695 for 5 passes (P = .02). Accuracy was dependent on the number of passes, with 5 passes (P = .018) having less PTH variation than 1 or 3 passes.

CONCLUSIONS

Aspiration of nodules to determine the PTH level helps confirm the presence of parathyroid tissue. The number of needle passes affects the accuracy of the PTH level, with 5 passes being the optimal number of passes to attain no false-negative results.