Primary hyperparathyroidism with surgical indication and negative or equivocal scintigraphy: Safety and reliability of PTH washout. A systematic review and meta-analysis

Objective: Despite the improvements in ultrasound (US) and scintigraphy, 10–20% of patients with primary hyperparathyroidism (PHPT) still have discordant findings. We performed a systematic review and meta-analysis to assess the safety and the diagnostic performance of US-guided PTH washout (FNA-PTH) in patients with PHPT, a suspected parathyroid lesion on US but negative or equivocal scintigraphy. Methods: The review was registered on PROSPERO (CRD42019124249). PubMed, Scopus, CENTRAL and Web of Science were searched until February 2019. Original articles reporting complications and diagnostic performance of FNA-PTH in biochemically and histopathologically diagnosed PHPT were selected. The risk of bias of included studies was assessed through QUADAS-2. Summary operating points were estimated using a random-effects model. Results: Out of 2573 retrieved papers, nine cohort studies were included in the review. No major procedure-related complications were found. Pooled sensitivity was 95% (95% CI: 91–98; I2: = 14%) and positive predictive value was 97% (95% CI: 93–100; I2: = 39%). There were not enough data for specificity and negative predictive value to perform a meta-analysis. However, pooling results of all lesions, they were estimated to be 83 and 73%, respectively. Conclusions: In patients with biochemically proven PHPT and discordant imaging, FNA-PTH was a safe and accurate procedure. In this specific setting of patients, FNA-PTH could be used as a rule-in test for minimally invasive parathyroidectomy.