Parathyroid glands are difficult to identify during total thyroidectomies, and accidental resection can lead to problematic postoperative hypocalcemia. Our main goals were to evaluate the effectiveness of using near-infrared light (NIRL) autofluorescence intraoperatively for parathyroid gland identification and to measure its impact on postoperative hypocalcemia incidence.

Total thyroidectomies were performed on 170 patients with different thyroid pathologies, block-randomized (1:1) into 2 equal groups. Among controls, traditional overhead white light (WL) was used throughout. In the experimental group, NIRL was used to enhance parathyroid gland recognition before thyroid dissection. The number of parathyroid glands identified was compared after thyroid dissection in controls using WL vs pre-dissection in the experimental using NIRL and with WL vs NIRL before thyroid dissection in the experimental group. Postoperative serum calcium levels and hypocalcemia rates were compared.

The mean number of parathyroid glands identified pre-dissection with NIRL was the same identified post-dissection with WL (3.5 vs 3.6). In the experimental group, converting from WL to NIRL increased the number of glands detected from 2.6 to 3.5 (p < 0.001), and revealed at least 1 previously missed gland in 67.1% of patients. Calcium levels ≤7.5 mg/dL were one-tenth as common in the NIRL group (p = 0.005). The adjusted odds of hypocalcemia developing increased by 15% for every 5-g increase in thyroid gland weight (odds ratio 1.15; 95% CI 1.06 to 1.25). All hypocalcemia resolved within 6 months.

Using NIRL during thyroidectomy increases intraoperative identification of parathyroid glands, enhances their detection before thyroid dissection, and decreases the incidence of postoperative hypocalcemia.