Diagnosis of parathyroid adenomas: efficacy of measuring parathormone levels in needle aspirates of cervical masses.

OBJECTIVE

The purpose of this study was to assess the value of measuring parathormone levels in percutaneous needle aspirates of suspicious cervical lesions in patients with hyperparathyroidism to confirm whether the lesion represents abnormal parathyroid tissue.

SUBJECTS AND METHODS

The study group consisted of 66 patients with hyperparathyroidism in whom 80 cervical lesions were aspirated and levels of parathormone in the aspirates were measured. CT guidance was used for two patients and sonographic guidance for the remainder. The lesions selected for aspiration were demonstrated on either sonography or CT and had either an unusual position (separate from the thyroid gland or were intrathyroidal) or configuration (irregular shape or atypical heterogeneous sonographic texture). In 15 patients, an indeterminate, posteriorly located intrathyroidal mass was detected and felt most likely to represent a thyroid nodule by sonographic criteria. These masses were aspirated to rule out atypical parathyroid adenomas. In patients who had been previously explored for hyperparathyroidism and presented with persistent or recurrent hypercalcemia, all indeterminate, cervical, potentially parathyroid masses were aspirated for parathormone determination. The level of parathormone in each aspirate was measured by using an immunoradiometric assay.

RESULTS

Levels of parathormone were increased in the aspirates in 37 of the 45 patients in whom sonography showed classic lesions suggestive of parathyroid adenoma. This included the 25 patients who had previously undergone exploratory surgery. At surgery, all 37 had parathyroid adenomas in the indicated locations, for a specificity of 100%. In six patients, the results of the aspiration were false-negative. Parathyroid adenomas were suspected on sonograms and confirmed at surgery, but no parathormone was detected in the aspirate. Results of aspiration of indeterminate lesions were true-negative in two patients who had both characteristic and indeterminate lesions on sonography and in the 15 patients who had indeterminate lesions that were felt to be of thyroid origin. Aspirates contained no parathormone, and surgical findings confirmed the lesions were not of parathyroid origin.

CONCLUSION

Our results show that increased levels of parathormone in percutaneous needle aspirates of cervical masses in patients with hyperparathyroidism confirm the mass is a parathyroid adenoma. Although absence or low levels of parathormone in the aspirates usually excludes a parathyroid adenoma, this is not absolute as sometimes the needle may miss the mass, rendering the parathormone value invalid (false-negative).