lntroduction: The optimal approach to parathyroidectomy (PTx) for primary hyperparathyroidism (PHPT) in Multiple Endocrine Neoplasia Type 1 (MEN 1) remains unclear. Reliable predictors of short and long-term outcomes could improve decision making regarding surgical approach and prognosis.
Methods: We conducted a retrospective cohort study involving 62 MEN 1 patients who underwent PTx with follow-up at the Royal Hobart Hospital. Preoperative and postoperative serum calcium and parathyroid hormone concentrations were extracted from medical records and analysed in relation to PTx extent: Total PTx (TPTx) = all glands removed; Near Total PTx (NPTx) = 0.5 glands retained; Subtotal PTx (SPTx) = 0.5-1 gland retained, Less Than Subtotal PTx (<SPTx) = more than 1 gland retained.
Outcomes: Rates of hypercalcaemia (HC), long-term remission (LR) (minimum follow-up 1 year), permanent hypocalcaemia (PH) or indeterminate (ID) were: TPTx (PH 100%), NPTx (HC 43%, LR 30%, PH 24%, ID 3%), SPTx (HC 86%, LR 0%, PH 14%), <SPTx (HC 67%, LR 27%, PH 0%, ID 6%). NPTx with parathyroid tissue autografting prevented PH 0% compared to 23% without autografting. NPTx (n=37) had significantly less hypercalcaemic events than SPTx (n=7) (p=0.01). Median duration to hypercalcaemia was: NPTx 203 months, SPTx 33 months. NPTx preoperative Calcium Homeostatic Ratio (CHR) (Ca2+/PTH-ratio) was associated with PH 50% (CHR <1.0) compared to PH 13% (CHR ≥1.0). NPTx week-1 postoperative Ca2+ was associated with HC 38%, LR 25%, PH 33%, ID 4% (Ca2+<1.10 mmol/L) compared to HC 64%, LR 36%, PH 0% (Ca2+≥1.10 mmol/L).
Conclusion: Parathyroidectomy in MEN 1 is associated with high rates of recurrence and permanent hypocalcaemia. NPTx with parathyroid tissue autografting provides an optimal balance between PHPT persistence, PHPT recurrence, long-term remission and risk of permanent hypocalcaemia. Preoperative CHR and week-1 postoperative Ca2+ levels were useful predictors of long-term PTx outcome and may enable prediction of individual patient prognosis.