Parathyroid Hormone Determination in Ultrasound-Guided Fine Needle Aspirates Allows the Differentiation between Thyroid and Parathyroid Lesions: Our Experience and Review of the Literature
Vincenzo Triggiani, Francesco Resta, Vito A. Giagulli, Michele Iovino, Brunella Licchelli, Giovanni De Pergola, Angela Tafaro, Marcello Benigno, Carlo Sabba and Edoardo Guastamacchia
Pages 351-358 (8)
In many cases, it is difficult or even impossible to distinguish parathyroid lesions from thyroid ones at
ultrasound as well as at scintiscan and even at cytology, because they often share common features. The aim of this study
was to evaluate the role of Parathyroid Hormone (PTH) determination in the aspirates in the differential diagnosis of
parathyroid from thyroid lesions in an area of mild iodine deficiency and high prevalence of thyroid nodules. Forty-six
consecutive patients were suspected to have one or more nodule(s) of parathyroid origin because of their position in the
posterior aspect of thyroid lobes and/or their shape and echo-pattern at ultrasound examination. In 13 cases, there were
also laboratory findings suggestive for primary hyperparathyroidism, with clinical evidence in 6 of these patients. A total
of 55 lesions suspected to be of parathyroid origin were selected. After obtaining cytological preparations, the needle used
to perform the fine-needle aspirate (FNA) was washed using 1 ml of normal saline. Intact PTH determination in the
washout was done whereas the evaluation was performed directly in the aspirated fluid in case of cystic lesions. The
values of PTH in the aspirates ranged from 6.7 to 16640 pg/ml. Sixteen patients underwent surgical intervention and the
histological examination of the 23 operated lesions previously submitted to FNA-PTH showed 11 parathyroid adenomas,
5 hyperplasic parathyroid lesions and 7 benign thyroid nodules. A strong positive correlation between high levels of PTH
in the aspirate and the histological findings of parathyroid lesions was found. A value over 245 pg/ml was constantly
associated to the parathyroid lesions. Our results confirmed the high accuracy of FNA-PTH determination in
differentiating parathyroid lesions from thyroid nodules and this is of special value in an area of mild iodine deficiency
with a high prevalence of thyroid nodules.
Fine-needle aspiration (FNA), hyperparathyroidism, parathyroid adenoma, parathyroid carcinoma, parathyroid
cyst, parathyroid hyperplasia, PTH assay, PTH determination, thyroid nodule, ultrasound-guided fine needle aspiration.
Endocrinology and Metabolic Diseases, University of Bari, Via Repubblica Napoletana n. 7, 70123 Bari, Italy.