High-intensity focused ultrasound to treat primary hyperparathyroidism: a feasibility study in four patients

Many patients with primary hyperparathyroidism either decline or are not candidates for surgical parathyroidectomy. There are drawbacks to medical therapy as well as percutaneous ethanol injection as alternative therapies for primary hyperparathyroidism. Therefore, in this pilot study, our aim was to test the feasibility, safety, and efficacy of a newly developed noninvasive high-intensity focused ultrasound (HIFU) technique for the nonsurgical management of primary hyperparathyroidism.

We treated four menopausal women with biochemical, sonographic, and cytologic evidence of benign primary hyperparathyroidism. HIFU treatment was performed in two sessions using TH-One under sonographic guidance and with the patient under conscious sedation. Parathyroid volume and function were evaluated at baseline and repeatedly until 12 months after the second HIFU session.

Serum parathyroid hormone levels decreased in all four patients and normalized 1 and 8 months after the second HIFU session in two patients. Serum calcium levels decreased in all patients and normalized in three patients. Three of four parathyroid tumors had decreased in size by 11%, 43%, and 79%, respectively, 12 months after the second HIFU session. All adverse events related to HIFU were transient: mild subcutaneous edema in three patients and impaired vocal cord mobility in one patient that resolved 40 days later.

HIFU is a promising procedure for patients with primary hyperparathyroidism that may become an alternative to established options, especially in elderly patients with comorbidities, or in patients who decline surgery. Large-scale long-term studies including patients with secondary and tertiary hyperparathyroidism are warranted.