Association of intraoperative mitoxantrone hydrochloride injection with incidental parathyroidectomy and parathyroid autotransplantation during gasless unilateral axillary endoscopic thyroidectomy: a propensity score-matched retrospective cohort study.

Background: Preserving parathyroid glands during thyroidectomy remains challenging, particularly in remote-access procedures. Mitoxantrone hydrochloride injection (MHI) is a local lymphotropic tracer that may improve intraoperative discrimination of parathyroid glands during gasless unilateral axillary endoscopic thyroidectomy (GUAET), but evidence remains limited. We evaluated whether intraoperative MHI was associated with a lower rate of incidental parathyroidectomy (IP) during GUAET and described parathyroid autotransplantation (PAT) as a separate management outcome. Methods: We performed a single-center retrospective cohort study of consecutive patients who underwent GUAET at a tertiary referral center in China between July 2020 and May 2024. Patients who received intraoperative MHI were compared with patients who underwent the same procedure without MHI. The primary outcome was IP. Secondary outcomes included PAT, short-term biochemical hypoparathyroidism [parathyroid hormone (PTH) <15 pg/mL], hypocalcemia (calcium <2.11 mmol/L), lymph node metrics, and postoperative symptoms. Nearest-neighbor 1:2 propensity score matching without replacement was performed using a 0.25-standard deviation caliper. Results: The study included 129 patients (31 in the MHI group and 98 in the control group). Propensity score matching yielded 93 patients (31 MHI and 62 controls). In the matched cohort, MHI was associated with a lower rate of IP [4/31 (12.9%) Conclusions: During GUAET, intraoperative MHI was associated with fewer IPs and more frequent PAT after propensity score matching. No clear differences were observed in short-term biochemical recovery, lymph node metrics, or postoperative symptoms.