Inclusion Criteria: 

1. Patients with persistent or recurrent primary hyperparathyroidism will be defined as having concomitant elevations of serum calcium and PTH and prior parathyroid surgery.

2. The patient is at least 3 months removed from their prior parathyroid surgery.

3. Meets 2014 criteria for parathyroid surgery and wants to consider parathyroid surgery as treatment for their primary hyperparathyroidism.

4. Nonlocalizing parathyroid scan and neck ultrasound performed at Mayo Clinic Rochester.

5. Patients aged 50 years and older with osteoporosis or osteopenia with a FRAX calculated 10-year risk of overall major osteoporotic fracture of ≥ 20% or 10-year hip fractures risk of ≥ 3%.

6. Women must be ≥ 1 year since their last menses.

7. Willing to consider denosumab as treatment for osteoporosis or osteopenia with increased fracture risk to decrease their risk of fracture.

8. 25-hydroxyvitamin D of ≥ 10 ng/ml.

Exclusion Criteria:

1. The patient is mentally or legally incapacitated, or otherwise unable to give informed consent.

2. Evidence of familial benign hypocalciuric hypercalcemia.

3. Renal insufficiency as defined by serum creatinine > 2.0 mg/dL or eGFR < 30 ml/minute.

4. Patients with primary hyperparathyroidism not eligible for surgery due to a high surgical risk related to underlying medical conditions.

5. Patients with primary hyperparathyroidism due to multiple endocrine neoplasia (MEN) syndromes or parathyroid cancer.

6. Use of medications that may alter serum calcium levels such as cinacalcet, estrogen therapy, raloxifene, teriparatide, hydrochlorothiazide, lithium, or intravenous bisphosphonates.

7. Treatment with oral bisphosphonates or denosumab within the last 1 year.

8. Known contraindication, intolerance, or allergy to denosumab, or is a poor candidate for denosumab.

9. Active dental issues necessitating consideration of tooth extraction.