Background and objectivesAccurate identification and evaluation of the parathyroid glands (PGs) intraoperatively is critical to reduce the incidence of postoperative hypoparathyroidism after total thyroidectomy. Near-infrared fluorescence imaging (NIFI), including the autofluorescence (AF) and indocyanine green fluorescence (ICGF) imaging, is a promising technique to protect PGs. This study aimed to assess whether the combined use of AF and ICGF could reduce the incidence of postoperative hypoparathyroidism and improve the identification and evaluation of PGs during total thyroidectomy.MethodsThis randomized controlled trial enrolled 180 patients who were randomized into two groups and underwent total thyroidectomy with unilateral or bilateral central lymph node dissection. In the control group, the PGs were identified and evaluated by the naked eye. In the NIFI group, AF was used to identify the PGs and ICGF was applied to assess the blood perfusion of the PGs in situ. The primary outcome was the incidence of postoperative hypoparathyroidism. The secondary outcomes included the number of identified PGs, autotransplanted PGs, and known preserved PGs in situ.ResultsThe incidence of postoperative transient hypoparathyroidism was significantly lower in the NIFI group than in the control group (27.8% vs. 43.3%, P = 0.029). More PGs were identified in the NIFI group than in the control group (3.6 ± 0.5 vs. 3.2 ± 0.4, P < 0.001). No significant difference was observed in the number of autotransplanted PGs between the two groups (P = 0.134). Compared with the control group, a greater number of known PGs were preserved in situ in the NIFI group (1.3 ± 0.6 vs. 1.0 ± 0.5, P < 0.001). In the NIFI group, only 4.5% of the patients with at least one well-perfused PG (ICG score of 2) developed postoperative hypoparathyroidism, which was significantly lower than that of the control group (34.6%, P < 0.001).ConclusionCombined use of AF and ICGF during total thyroidectomy reduces the risk of transient postoperative hypoparathyroidism, enhances the ability to identify and preserve PGs, and improves the accuracy of evaluating the perfusion of PGs during surgery.Clinical Trial RegistrationChinese Clinical Trial Register (www.chictr.org.cn), identifier ChiCTR2100045320. Registered on April 12, 2021.

IntroductionPostoperative hypoparathyroidism (POH) is the most common and important complication for thyroid cancer patients who undergo total thyroidectomy. Intraoperative parathyroid autotransplantation has been demonstrated to be essential in maintaining functional parathyroid tissue, and it has clinical significance in identifying essential factors of serum parathyroid hormone (PTH) levels for patients with parathyroid autotransplantation. This retrospective cohort study aimed to comprehensively investigate influential factors in the occurrence and restoration of POH for patients who underwent total thyroidectomy with intraoperative parathyroid autotransplantation (TTIPA).MethodThis study was conducted in a tertiary referral hospital, with a total of 525 patients who underwent TTIPA. The postoperative serum PTH levels were collected after six months, and demographic characteristics, clinical features and associated operative information were analyzed.ResultsA total of 66.48% (349/525) of patients who underwent TTIPA were diagnosed with POH. Multivariate logistic regression indicated that Hashimoto’s thyroiditis (OR=1.93, 95% CI: 1.09-3.42), P=0.024), the number of transplanted parathyroid glands (OR=2.70, 95% CI: 1.91-3.83, P<0.001) and postoperative blood glucose levels (OR=1.36, 95% CI: 1.06-1.74, P=0.016) were risk factors for POH, and endoscopic surgery (OR=0.39, 95% CI: 0.22-0.68, P=0.001) was a protective factor for POH. Multivariate Cox regression indicated that PTG autotransplantation patients with same-side central lymph node dissection (CLND) (HR=0.50; 95% CI: 0.34-0.73, P<0.001) demonstrated a longer time for increases PTH, and female patients (HR=1.35, 95% CI: 1.00-1.81, P=0.047) were more prone to PTH increases. Additionally, PTG autotransplantation with same-side CLND (HR=0.56, 95% CI: 0.38-0.82, P=0.003) patients had a longer time to PTH restoration, and patients with endoscopic surgery (HR=1.54, 95% CI: 1.04-2.28, P=0.029) were more likely to recover within six months.ConclusionHigh postoperative fasting blood glucose levels, a large number of transplanted PTGs, open surgery and Hashimoto’s thyroiditis are risk factors for postoperative POH in TTIPA patients. Elevated PTH levels occur earlier in female patients and patients without CLND on the transplant side. PTH returns to normal earlier in patients without CLND and endoscopic surgery on the transplant side.