Abnormally elevated serum calcium 6 mo after a parathyroidectomy for HPT

End

4D CT, Four-dimensional computed tomography; FNA, fine-needle aspiration; IONM, intraoperative neurophysiologic monitoring; IOPTH, intraoperative parathyroid hormone; PTH, parathyroid hormone; sestamibi, technetium (^99mTc) sestamibi imaging; US, ultrasonography.

Confirm diagnosis of HPT (assess vitamin D levels). Physical examination of the patient (placement of the incision, body habitus, voice changes, etc.). Vocal cord assessment. Family history review. Review prior imaging studies, records from initial operation, and pathology reports from initial operation.

Persistent HPT
Serum calcium levels remain abnormally high during the first 6 mo postoperatively and never normalize

Causes
Missed gland
Multigland disease
Incomplete resection
Parathyroid cancer

Recurrent HPT
Serum calcium levels normalize during the first 6 mo after initial operation and then increase to abnormal levels

Causes
Multigland disease
Multiple endocrine neoplasia type 1
Parathyroid cancer
Regrowth of remnant
Parathyromatosis

Perform a combination of cervical US, sestamibi, and 4D CT. Consider FNA to obtain PTH levels and cytology. Utilize venous sampling selectively.

If the location of a single missed gland is confirmed, proceed to reoperation. Utilize as needed: IOPTH assay, intraoperative US, IONM.

If multifocal disease is suspected, review location of glands removed, plan completion, subtotal parathyroidectomy

If culprit gland(s) are not identified, continue monitoring, reevaluate the patient’s status with new imaging studies in 1-2 yr