Primary Hyperparathyroidism due to Superior Parathyroid Adenoma

Introduction to Superior Parathyroid Adenoma

A superior parathyroid adenoma is a benign neoplasm arising from one of the two superior parathyroid glands, which is the most common cause of primary hyperparathyroidism and represents approximately 80% of all cases 1

Primary hyperparathyroidism from parathyroid adenomas is recognized as a secondary cause of hypertension in major cardiovascular guidelines 2
Biochemical confirmation must precede imaging, as imaging has no utility in confirming or excluding the diagnosis of primary hyperparathyroidism 3, 1
Measure serum calcium (corrected for albumin) and intact PTH simultaneously; hypercalcemia with normal or elevated PTH is diagnostic 4

Include 25-OH vitamin D levels to exclude vitamin D deficiency as a concomitant secondary cause 4
Imaging is performed solely for preoperative localization to facilitate minimally invasive parathyroidectomy (MIP), not for diagnosis 1
First-line imaging includes ultrasound and 99mTc-sestamibi scintigraphy with SPECT/CT when available 4
4-D parathyroid CT (noncontrast, arterial, and venous phases) leverages unique perfusion characteristics to differentiate adenomas from thyroid nodules and lymph nodes 3, 1

Surgical excision is the definitive curative treatment and is typically indicated even when asymptomatic, given the potential negative effects of long-term hypercalcemia including persistent hypertension 1, 2
Persistent hyperparathyroidism (failure to achieve normocalcemia within 6 months) or recurrent disease (hypercalcemia after ≥6 months of normocalcemia) requires preoperative imaging to localize target lesions and identify postoperative changes 1

The sensitivity of sestamibi imaging is reduced when hypercalcemia is mild or absent, and the test offers no diagnostic value without biochemical evidence of primary hyperparathyroidism. The American College of Radiology notes that in such settings the scan’s usefulness is limited. 5
In patients with confirmed primary hyperparathyroidism, sestamibi scans demonstrate a sensitivity ranging from 67 % to 86 %, but false‑positive results can occur due to thyroid nodules. These performance figures are reported by the American College of Radiology. 5

Pre‑operative parathyroid localization with sestamibi (or ultrasound) should be performed only when biochemical primary hyperparathyroidism is established (persistent hypercalcemia with elevated or inappropriately normal intact PTH) and surgery is being planned. This recommendation follows the American College of Radiology imaging guidelines. 5

Dual‑phase sestamibi imaging combined with SPECT/CT provides a pooled sensitivity of 86 % and is identified by the American College of Radiology as the preferred modality for pre‑operative localization of parathyroid adenomas. 5