Parathyroidectomy
What the Examiner Expects
Surgical removal of one or more parathyroid glands for primary hyperparathyroidism. The examiner expects you to confirm the biochemical diagnosis (elevated calcium with inappropriately elevated or non-suppressed PTH), perform localization studies (sestamibi scan and neck ultrasound — if concordant, a focused/minimally invasive approach is appropriate), and use intraoperative PTH monitoring to confirm cure. For single adenoma (85% of cases), focused parathyroidectomy removes only the abnormal gland. For four-gland hyperplasia (seen in MEN1, MEN2A, secondary/tertiary hyperparathyroidism), subtotal parathyroidectomy (3.5 glands removed, leaving a well-vascularized remnant) or total parathyroidectomy with forearm autotransplant is performed.
Key Examiner Focus Points
- Focused (minimally invasive) vs bilateral neck exploration
- Preoperative localization: sestamibi scan + neck ultrasound (concordant = focused approach)
- Intraoperative PTH monitoring (Miami criteria: > 50% drop from highest pre-excision level at 10 min)
- Four-gland hyperplasia (MEN1, secondary/tertiary HPT): subtotal parathyroidectomy (3.5 glands) or total with autotransplant
- Superior parathyroids derive from 4th branchial pouch; inferior from 3rd (more variable location)
Common Curveballs
Intraoperative PTH does not drop > 50% after removing the localized adenoma
A persistent elevated PTH means there is additional hyperfunctioning tissue. Convert to a bilateral neck exploration to find a second adenoma (double adenoma in ~5%) or four-gland hyperplasia. Check all four gland sites systematically. Consider ectopic locations: carotid sheath, thymus, retroesophageal, intrathyroidal.
The missing parathyroid gland cannot be found in the neck
Ectopic locations in order of frequency: thymus (most common ectopic site for inferior glands), retroesophageal/paraesophageal (superior glands), carotid sheath, intrathyroidal, and mediastinum. Perform a cervical thymectomy. If still not found, consider intraoperative ultrasound or close and obtain 4D-CT/sestamibi for re-localization.
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