THE RESULTS OF PARATHYROID HORMONE ASSAY IN PARATHYROID ASPIRATES IN PRE-OPERATIVE LOCALIZATION OF PARATHYROID ADENOMAS FOR FOCUSED PARATHYROIDECTOMY IN PATIENTS WITH NEGATIVE OR SUSPICIOUS TECHNETIUM-99M-SESTAMIBI SCANS.

Objective: This study aimed to evaluate the results of parathyroid hormone (PTH) assay in parathyroid aspirates to determine uniglandular disease by an endocrinologist-performed ultrasound (US) in patients with discordant or negative technetium-sestamibi scans and to evaluate whether this procedure increases the number of focused parathyroidectomies (FPs).

Methods: We analyzed the data of 65 patients who underwent an endocrinologist-performed US-guided parathyroid fine-needle aspiration (FNA) with PTH wash-out, retrospectively. The results of PTH wash-out procedure and the reports of parathyroid surgery and pathology were reviewed.

Results: Of 65 patients, 54 had positive PTH wash-out results. The median serum PTH level of patients with positive and negative PTH wash-out results was 143 (25 and 75% interquartile range [IQR], 114 to 197) versus 154 (IQR, 115 to 255) pg/mL (P = .45), and the median PTH in FNA was 3,533 (IQR, 1,481 to 3,534) versus 6.0 (IQR, 1 to 6) pg/mL (P<.001), respectively. Forty-five patients underwent surgery. Of the operated patients, 42 had positive PTH wash-out results and had successful FP. Four patients with redo surgery had positive PTH wash-out results and were successfully re-operated with FP. Of 11 patients with negative PTH wash-out results, 3 had bilateral neck exploration (BNE) surgery and 2 patients were successfully operated, while surgery was unsuccessful in 1 patient, despite BNE.

Conclusion: Our study results suggest that endocrinologist-performed US and parathyroid FNA with PTH wash-out increases the number and success of FPs. In particular, patients with redo surgery may benefit from this procedure.

Abbreviations: 4D-CT = four-dimensional computed tomography BNE = bilateral neck exploration FNA = fine-needle aspiration FNAB = fine-needle aspiration biopsy FP = focused parathyroidectomy IQR = 25 and 75% inter-quartile range PHPT = primary hyperparathyroidism PPV = positive predictive value PTH = parathyroid hormone Tc = technetium US = ultrasound.