Endocrine Abstracts

Objective: Evaluate the utility of analytical determination of parathyroid hormone assay in fine-needle aspirate as a diagnostic test for parathyroid adenoma in patients with primary hyperparathyroidism.

Material and Methods: retrospective observational study of 58 patients diagnosed with primary hyperparathyroidism in our hospital who underwent ultrasound-guided FNA of lesions compatible with parathyroid adenoma with determination of PTH in fine-needle aspirate (PTHL). A cut-off point for PTHL of 100 pg/ml was considered positive.

Results: 70.7% of the sample was female and the mean age was 59.2±13.3 years. Fifty-eight lesions were punctured with a mean diameter of 12.78±11.55 mm, and no procedure-related complications were recorded. Sestamibi-Tc99m gammagraphy showed no uptake in 85.9% of cases, intra-thyroid adenoma was suspected in 8.6% of cases and in 74.1% there was discordance between localization tests (ultrasound, gammagraphy, 4D parathyroid CT). The mean PTH_L value was 3399.7±7776.2 pg/ml, and 74.1% of cases were considered positive. Until the analysis was performed, 31 patients had undergone surgery and the result of the surgery was concordant with the localised lesion by PTHL in 83.9% of the cases. The determination of PTHL (≥ 100 pg/ml), in our series, has a sensitivity of 93%, a positive predictive value of 100%, a specificity of 100% and a negative predictive value of 60%. Two false negative cases were observed with PTHL values of 9 and 72 pg/ml.

Conclusion: PTH measurement in FNA aspirate is an affordable and useful diagnostic test to confirm the location of parathyroid adenoma. Further studies are needed to establish a standardised cut-off point for PTHL. This technique could be established as a complementary or safe alternative test in cases with difficult localisation or discordant localization tests.