The usefulness of parathyroid hormone and calcitonin detection from needle aspirates (FNAB) in patients with mutinodular goitre.

Objective: To evaluate the usefulness of parathyroid hormone (PTH) and calcitonin (CT) assay in FNAB (PTHn and CTn) in the pre-surgical localization of parathyroid neoplasia (PN) or medullary thyroid carcinoma (MTC). Patients and Methods: Twenty patients [17 with multinodular goiter (MNG)] with suspect primary hyperparathyroidism (PHP) and 11 with high serum CT (7 with MNG) were submitted to neck ultrasound (US) and US-guided FNAB of suspicious lesions for cytology and PTHn or CTn; sesta-MIBI parathyroid scintigraphy (MIBI) and pentagastrin (PG) test were also performed in patients with PHP and high CT, respectively. Results: In PHP, 17/20 patients showed high (366 - >5000 pg/ml) PTHn and a PN at histology; the remaining 3 cases had a thyroid neoplasia (TN) associated to secondary hyperparathyroidism. The sensitivity and the specificity of PTHn was therefore 100%. MIBI was positive in 15 (13 PN and 2 TN) and negative in 5 (4 PN and 1 TN) reaching 76% sensitivity and 33% specificity. Cytology was diagnostic in 10 (all PN) and not-diagnostic in 10 cases (7 PN and 3 TN: 58% sensitivity and 100% specificity). Among the 11 patients with high serum CT, 8 had high (68 - >2000 pg/ml) CTn, positive PG test and a MTC at histology. Three cases showed undetectable CTn: 2 of them, with negative cytology and borderline PG test, were not operated; in the remaining patient with positive PG test and dubious cytology (with suspicious neck MTC recurrence after thyroidectomy) histology showed an inflammatory process. Thus, CTn reached 100% sensitivity and specificity. Cytology correctly identified 3 and was not-diagnostic in 5 patients with histologically proven MTC, (37% of sensitivity and 66% specificity). Conclusions: PTHn and CTn represent the most sensitive and specific available tool to plan a correct pre-surgical localization of PN and MTC even in the presence of multinodular goiter.