What is the management approach for an adult patient with primary hyperparathyroidism due to a parathyroid adenoma, particularly in regards to intraoperative parathyroid hormone (PTH) washout and post-operative care to prevent complications of hyperparathyroidism?

Intraoperative PTH Monitoring for Parathyroid Adenoma

Intraoperative PTH monitoring is essential during minimally invasive parathyroidectomy for parathyroid adenoma, with a >50% PTH decline at 10 minutes post-excision confirming successful removal of the hyperfunctioning gland. 1

Surgical Approach Selection

Minimally invasive parathyroidectomy (MIP) is the preferred approach when preoperative imaging confidently localizes a single parathyroid adenoma, offering shorter operating times, faster recovery, and decreased perioperative costs compared to bilateral neck exploration. 1

• MIP requires confident preoperative localization through imaging (sestamibi scan or 4D-CT) combined with intraoperative PTH monitoring to confirm adequate resection. 1
• Bilateral neck exploration remains necessary when imaging is discordant, non-localizing, or when multigland disease is suspected (15-20% of cases). 1

Intraoperative PTH Monitoring Protocol

The standard protocol measures PTH at three time points: baseline (at anesthesia induction), 5 minutes post-excision, and 10 minutes post-excision. 2

• A PTH decline >50% at 10 minutes post-excision predicts surgical cure with high accuracy. 2
• In one validated series, this criterion correctly predicted surgical success in all 28 measurements performed, including one case where inadequate PTH decline prompted continued exploration that identified a contralateral adenoma missed on preoperative imaging. 2
• If PTH fails to decline >50%, continue surgical exploration to identify additional hyperfunctioning glands or ectopic adenomas. 2

Post-Operative Management and Complications

Monitor for hypocalcemia immediately post-operatively, as PTH levels become undetectable after successful adenoma removal, creating risk for hungry bone syndrome. 3

• Check serum calcium at 24 hours post-operatively to confirm normocalcemia and assess for hypocalcemia. 2
• Initiate calcitriol and calcium supplementation immediately if hypocalcemia develops, typically for 1-4 months duration depending on severity. 3
• Persistent hypercalcemia beyond 6 months indicates persistent hyperparathyroidism (surgical failure), while hypercalcemia developing after 6+ months of normocalcemia indicates recurrent disease. 1

Critical Pitfalls to Avoid

The most common surgical failure occurs when a normal parathyroid gland is removed instead of the adenoma, emphasizing why intraoperative PTH monitoring is non-negotiable for MIP. 2

• Always obtain baseline PTH before any gland excision to establish the reference point for the 50% decline criterion. 2
• Consider ectopic locations (submandibular, mediastinal) if PTH fails to decline despite removing a suspected adenoma—functional imaging with F-choline PET/CT may be needed. 4
• Multigland disease (multiple adenomas or hyperplasia) affects 15-20% of patients and will not show adequate PTH decline after single gland removal. 1

Indications for Surgery

Surgery is indicated even in asymptomatic patients due to long-term morbidity from chronic hypercalcemia, including bone demineralization, nephrolithiasis, and cardiovascular effects including hypertension. 1, 5

• Symptomatic patients (bone pain, recurrent nephrolithiasis, neurocognitive symptoms) require prompt parathyroidectomy without delay for medical management. 5
• Parathyroid crisis (severe hypercalcemia with neurological symptoms) carries 100% mortality without surgery and 20% mortality even with parathyroidectomy, requiring aggressive initial medical stabilization followed by urgent surgery. 6