General consensus and contemporary guidelines, recommend surgery for primary hyperparathyroidism (pHPT)for all patients below the age of 50, for patients with pronounced hypercalcemia and for patients with organ complications to the disease (osteoporosis and decreased renal function).

The purpose of this study is to determine if surgery for pHPT, is appropriate for patients with moderate to mild hypercalcemia older than 65 years of age.

The hypothesis of the study is that surgery for pHPT in patients older than 65 years of age, and with mild hypercalcemia, will increase bone density and hence decrease future risk for fragility fractures compared to patients with follow-up only.

The majority of patients diagnosed and operated due to primary HPT in Scandinavia are older than 65 years of age. The vast majority of the patients have mild aberrations of serum calcium (< 1.50 mmol/l ionized calcium), and some patients may even be asymptomatic. The present trial is designed to clarify the indications for surgical treatment in this large subgroup of patients.

Inclusion Criteria:

• Primary Hyperparathyroidism
• No previous parathyroid surgery
• Sporadic disease

Exclusion Criteria:

• Z-score of Bone density < -2.5 SD (regardless of site)
• Serum level of ionized calcium > 1.50 mmol/L
• Inability to understand given information or to comply with scheduled follow-up
• Symptoms of hypercalcaemia for which specific medical treatment has been prescribed