What test can confirm primary hyperparathyroidism?

Confirmation of Primary Hyperparathyroidism

Primary hyperparathyroidism is confirmed through biochemical testing, specifically elevated serum calcium levels with elevated or inappropriately normal parathyroid hormone (PTH) levels. 1, 2

Diagnostic Approach

• The diagnosis of primary hyperparathyroidism is biochemical, not radiological - imaging has no role in confirming or excluding the diagnosis 3, 1
• Serum calcium measurement combined with PTH level is the definitive test for confirming primary hyperparathyroidism 3, 2
• Asymptomatic hypercalcemia is the most frequent manifestation of primary hyperparathyroidism 2

Key Biochemical Tests for Confirmation

• Serum calcium (elevated or high-normal) with concurrent elevated or inappropriately normal PTH levels 3, 2
• Additional laboratory tests to support diagnosis and rule out secondary causes:
  • Serum phosphate (typically low in primary hyperparathyroidism) 2
  • Serum chloride 2
  • 25-hydroxyvitamin D levels (to rule out vitamin D deficiency) 2
  • 1,25-dihydroxyvitamin D levels 2
  • Calcium-to-creatinine clearance ratio 2

Important Clinical Considerations

• Primary hyperparathyroidism must be distinguished from secondary hyperparathyroidism, where PTH elevation is appropriate in response to another condition 2
• Biochemical confirmation should always precede any imaging studies 1
• Imaging studies (ultrasound, sestamibi scans) are used only for preoperative localization after biochemical confirmation, not for diagnosis 3, 1

Common Pitfalls to Avoid

• Relying on imaging studies to make the diagnosis - this is incorrect as imaging has no role in confirming or excluding the diagnosis 1
• Failing to measure both calcium and PTH simultaneously - both are required for proper diagnosis 3, 2
• Not considering familial hypocalciuric hypercalcemia as a differential diagnosis, which requires calcium-to-creatinine clearance ratio assessment 2
• Proceeding to imaging before biochemical confirmation - this approach is not recommended by clinical guidelines 1

Clinical Scenarios Warranting Evaluation

• Patients with nephrolithiasis or nephrocalcinosis 2
• Patients with osseous pain, subperiosteal resorption, or pathologic fractures 2
• Patients with osteoporosis or osteopenia 2
• Patients with history of neck irradiation 2
• Family history of multiple endocrine neoplasia syndrome (types 1 or 2) 2