Identification of inadvertently removed parathyroid glands during thyroid surgery using autofluorescence

Incidental excision of parathyroid glands is a common event during thyroid surgery and in spite the divergent results that can be obtained from the literature about its clinical significance, all efforts must be used to their preservation. Due to the autofluorescence emitted by parathyroid glands, authors began to use a custom device to inspect thyroidectomy specimens for incidentally removed parathyroid tissue; the results of using this device are presented in this manuscript.

Specimens of 40 consecutive thyroid surgeries were inspected. Localization of suspect high-fluorescence spots were recorded for confirmation with a pathological exam. Determinations of calcium and parathyroid hormone (PTH) were completed prior to surgery and at 24 hours and 15 days after the operation.

Patient age ranged from 36 to 83 years and were predominantly female (82.5%). Calcium values at 24 hours post-operation varied between 7.1 and 9.5. The PTH values ranged between 3 and 77. Thirteen patients (32.5%) presented with biochemical hypocalcemia at 24 hours. At 15 days after the operation, only one patient presented with a calcium value below 8 (PTH: 10.9) with complete normalization 6 months after the surgery. Pathological examination identified eight parathyroid fragments in seven patients. There was no correlation between the presence of parathyroid tissue in the specimen and post-operative hypocalcemia (P=0.254). Eight suspicious areas of augmented fluorescence where detected; seven were coincident with the pathological examination and one was a false positive. One intrathyroidal gland was not identified, resulting a sensitivity of 87.5% and specificity 96.2%.

Although no correlation between incidental parathyroidectomy and hypocalcemia was demonstrated, autofluorescence may be a useful tool for in-table identification of incidentally-removed glands.