A prospective evaluation of novel methods to intraoperatively distinguish parathyroid tissue utilizing a parathyroid hormone assay

BACKGROUND: Frozen section analysis has traditionally been used to confirm the identity of parathyroid tissue intraoperatively; however, it is time-consuming and costly and requires the excision of a significant portion of tissue. An intraoperative biopsy and analysis with a parathyroid hormone (PTH) assay is a possible alternative; however, this technique has not been perfected. METHODS: Two hundred twenty-three tissue specimens were collected prospectively from patients undergoing neck exploration. Each specimen was sampled intraoperatively using three different biopsy techniques: a fine-needle aspiration (FNA) with 10 passes of a needle (FNA10), a FNA with 20 passes of a needle (FNA20), and a tissue biopsy of approximately 1.0 mm3 (BIOPSY). The PTH concentration of each sample was determined via the Elecsys 1010 PTH immunoassay. The final tissue diagnosis was determined by histology or operative data. RESULTS: Parathyroid samples from all techniques had higher median PTH concentrations than nonparathyroid samples. However, the accuracies for the detection of parathyroid tissue varied markedly (PTH cutoff of 1000 pg/ml): the accuracies of the FNA10 and FNA20 were 71 and 80%, respectively, while the BIOPSY was 99% accurate. CONCLUSIONS: This is the first prospective study evaluating multiple methods to diagnose parathyroid tissue intraoperatively using a rapid PTH assay. We conclusively show that the BIOPSY technique is 99% accurate for the diagnosis of parathyroid tissue, and therefore, should be the method of choice when the intraoperative confirmation of parathyroid tissue is needed.