Inclusion Criteria:
* Participants at least 21 years of age.
* Participant has classical hyperparathyroidism defined by elevated albumin-corrected serum calcium, serum ionized calcium and intact parathyroid hormone level
* Participant qualifies for surgery to treat PHPT according to AAES guidelines as follows: Symptomatic PHPT patients diagnosed with primary hyperparathyroidism (clinical symptoms and/or biochemical disturbances), such as those with symptoms in any system including the kidneys, bones, gastrointestinal tract, psychoneurological system, or those with atypical symptoms such as muscle weakness, dysfunction, and sleep disorders; OR Asymptomatic PHPT patients with any of the following conditions:
1. Serum calcium is higher than the upper limit of the normal value by 1 mg/dL (0.25 mmol/L);
2. There is objective evidence of renal involvement, including asymptomatic kidney stones, nephrocalcinosis, hypercalciuria (24 - hour urinary calcium level \> 250mg/dL for women and \>300mg/dl for men), on renal imaging, or impaired renal function (glomerular filtration rate \< 60 mL/min);
3. There is evidence of osteoporosis (bone mineral density decreased by 2.5 standard deviations at any site) and/or radiographic evidence of fragility fractures;
4. Age \< 50 years;
5. The participant is willing and able to comply with study procedures including all follow-up visits. Patient desires an intervention but doesn't want surgery
* One diseased parathyroid gland (≥ 1cm in greatest dimension), by ultrasonography and four-phase CT scan.
* The diseased targeted parathyroid gland is accessible for nsPFA treatment.
* Participants are willing and able to provide voluntary, written informed consent to participate in this study.
Exclusion Criteria:
* Participants have an implantable electronic medical device (i.e., pacemaker, implantable cardioverter defibrillator).
* Diagnosis of secondary or tertiary hyperparathyroidism.
* Known spondylitis of the neck vertebrae.
* Head and/or neck disease that prevents hyperextension of neck.
* Known history of previous thyroid or parathyroid surgery or ablation for a neoplasm in the neck region.
* History of neck irradiation.
* Anesthesia drug allergies.
* Patients whose concurrent illnesses, disability, or geographical residence would hamper attendance at required study visit(s).
* Participants are pregnant at the time of screening or within 30 days prior to enrollment.
* Participants who have received any investigational drug or device within 30 days and/or participants who are currently participating in another clinical trial.
