Intraoperative PTH monitoring during parathyroidectomy for primary hyperparathyroidism: what is the Miami criterion for predicting cure?
- A PTH falls by >50% from the highest pre-excision value and into the normal range at 10 minutes post-excision ✓
- B PTH falls by >30% from baseline at 10 minutes post-excision
- C PTH normalizes (<65 pg/mL) at 5 minutes post-excision regardless of percentage drop
- D PTH falls below 20 pg/mL at any point during dissection
Correct answer: A. PTH falls by >50% from the highest pre-excision value and into the normal range at 10 minutes post-excision
Explanation
The Miami criterion (Irvin protocol) defines cure as a >50% drop from the highest pre-excision PTH value and a fall into the normal range at 10 minutes after excision of the suspected gland. This predicts single-gland disease and guides the surgeon to terminate exploration or continue seeking multiglandular disease. A drop of only 30% is insufficient and may signal missed disease. Absolute PTH thresholds alone are less reliable because some patients have high baseline levels with target organs responding to relative changes.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.