US-guided microwave ablation for primary hyperparathyroidism: a safety and efficacy study

Objectives To evaluate the safety and efficacy of microwave ablation (MWA) with the assistance of continuous cool saline injection (CCSI) in patients with primary hyperparathyroidism (PHPT). Methods Between November 1, 2014, and February 29, 2016, 22 patients with PHPT were enrolled and treated with ultrasound-guided MWA assisted by CCSI. The levels of parathyroid hormone (PTH) and serum calcium were recorded before and after the MWA. Patients were divided into two groups (normalized and unnormalized groups) according to treatment efficacy. Fisher’s exact test and the Mann-Whitney test were used to compare data between the two groups. Timing differences in serum PTH and calcium levels were analyzed with repeated measures analysis of variance. Results Normalized outcomes for both PTH and calcium levels were achieved in 19 of 22 (86.36%) patients with PHPT. In the normalized group, PTH levels remained normal for 12 months after MWA. PTH levels in the unnormalized group were outside the reference range at six of seven follow-ups within 12 months following MWA. By contrast, serum calcium levels gradually decreased in all patients in both groups. The mean serum PTH and mean calcium levels at 6 months after therapy were significantly lower than those before MWA (both p < 0.05). A transient voice change developed in eight patients. One patient experienced hypocalcaemia, which was corrected by oral calcium supplementation within 2 months. Conclusions US-guided MWA assisted by CCSI is safe and effective for destroying parathyroid gland tissue and may serve as a therapeutic alternative for patients with PHPT. Key Points • Microwave ablation is a new option for patients with hypercalcemic or normocalcemic primary hyperparathyroidism. • Microwave ablation can decrease PTH and calcium levels with sustained efficacy in most patients. • Treatment is safe and causes only transient side effects.