Preoperative ultrasound in primary hyperparathyroidism

A 69-year-old woman presented last week for consultation regarding hypercalcemia due to primary hyperparathyroidism. She has had elevated total calcium on multiple occasions: 10.9, 11.5 and 11.9 mg/dL (8.4-10.5 mg/dL) along with elevated parathyroid hormone: 66 pg/mL (15-50 pg/mL). The 24-hour urine calcium was 518 mg/24 hrs (100-300 mg/24 hrs) and 25-OH vitamin D was 60 mg/dL (optimal >30 mg/dL). She denied history of kidney stone or fracture but bone mineral densitometry revealed a T-score of –2.4 in L1-L4.

The technetium sestamibi parathyroid scan showed retained activity in the right lower thyroid and also an enlarged right thyroid lobe.

I performed neck ultrasound in the office. Technetium sestamibi parathyroid scans can be positive in patients with thyroid cancer as well as benign thyroid nodular disease. Myself, I have seen two cases of thyroid cancer initially detected by technetium sestamibi scan. The ultrasound identified a highly vascular hypoechoic 1.72-cm mass with irregular margins in the right lower lobe of the thyroid. Its appearance was not classic for a parathyroid adenoma nor was it typical for a benign thyroid nodule.

Coexisting thyroid disease has been reported to be present in 20% to 60% of patients with primary hyperparathyroidism. According to Milas and colleagues, incidental discovery of thyroid abnormalities during parathyroidectomy led to total or partial thyroidectomy in 30% of patients. Ultrasound imaging before parathyroidectomy resulted in ultrasound-guided fine needle aspiration of thyroid nodules in 20%. This reduced concomitant thyroid surgery during parathyroidectomy to only 6%. Preoperative ultrasonography in primary hyperparathyroidism can be a cost-effective tool to determine the best surgical approach and to reduce unnecessary thyroid surgery.

Ultrasound-guided fine needle aspiration combined with parathyroid hormone assessment further improves the sensitivity of ultrasonography. If the suspicious lesion is parathyroid, the parathyroid hormone of needle washout of the fine needle aspiration will be strongly positive, often in the tens of thousands. I performed ultrasound-guided fine needle aspiration along with parathyroid assessment of three combined samples. The parathyroid hormone was 29,678 pg/mL, confirming that this unusual mass is parathyroid and not thyroid.

Our patient will be seeing the surgeon in the near future.

For more information:
Hustad KV, Staub UH, Buð MI. Clin Nucl Med. 2007;32: 548-550.
Milas M, Mensah A, Alghoul M, et al. Thyroid. 2005;15(9):1055-1059.
Bentrem DJ, et al. Thyroid. 2002;12(12):1109-1112.
Barczynski M, Golkowski F, Konturek A. Clin Endocrinol. 65:106-113.
Abraham D, et al. Endocr Pract. 2007;13(4):333-337.