title: Intraoperative photodynamic detection of normal parathyroid glands using 5-aminolevulinic acid.
abstract: OBJECTIVE
  It is important to identify and save the normal parathyroid glands during head and neck surgery because of their role in regulating the blood calcium level, yet it is often difficult to localize normal parathyroid glands during surgery. Fluorescence-guided parathyroidectomy in patients with hyperparathyroidism has already proved useful. However, there are few reports of fluorescence-guided localization of normal parathyroid glands in humans. We investigated the utility of fluorescence-guided localization of normal parathyroid glands during thyroidectomy and completed a spectral fluorescence analysis of the accumulation of 5-aminolevulinic acid metabolites in the parathyroid glands.
  
  
  METHODS
  Eight patients with benign thyroid disease and five with malignant thyroid tumors were given 20 mg/kg body weight of 5-aminolevulinic acid orally 5 hours before surgery. After the posterior surface of the thyroid gland was exposed and the recurrent laryngeal nerve was identified, we illuminated the area with a violet-blue light of 405 nm. Tissues showing red fluorescence were biopsied to analyze the spectral fluorescence.
  
  
  RESULTS
  Under the violet-blue light, normal parathyroid glands showed red fluorescence, while the surrounding structures such as the thyroid gland, muscles, and fat remained nonfluorescent. The spectral peak was observed at 635 nm indicating 5-aminolevulinic acid metabolites. Histopathologically, the biopsied tissue corresponded to normal parathyroid glands.
  
  
  CONCLUSIONS
  5-Aminolevulinic acid is useful to localize the normal parathyroid glands during thyroid surgery in humans.
authors.affiliation: Department of Head and Neck Surgery, National Hospital Organization Chiba Medical Center, Chiba City, Chiba, Japan. ttn3hyi@gmail.com
authors.forename: Takeshi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Numata
authors.forename: Mariko
authors.initials: M
authors.lastname: Shibuya
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000622:Aminolevulinic Acid; D005260:Female; D005453:Fluorescence; D006801:Humans; D006980:Hyperthyroidism / Q000175:diagnosis / Q000601:surgery; D007430:Intraoperative Care / Q000379:methods; D008297:Male; D008875:Middle Aged; D010280:Parathyroid Glands / Q000033:anatomy & histology* / Q000187:drug effects; D017319:Photosensitizing Agents; D011183:Postoperative Complications / Q000517:prevention & control; D012016:Reference Values; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D013959:Thyroid Diseases / Q000175:diagnosis / Q000601:surgery*; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000601:surgery; D013965:Thyroidectomy / Q000009:adverse effects / Q000379:methods*
chemical_list: D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid