title: Identification of pathological and normal parathyroid tissue by fluorescent labeling with 5-aminolevulinic acid during endocrine neck surgery.
abstract: BACKGROUND
  When performing parathyroid or thyroid surgery, surgeons must distinguish parathyroid tissue from the surrounding thyroid tissue, to preserve healthy parathyroid tissue while excising diseased thyroid tissue or to completely remove pathological parathyroid lesions. Here, we explored the feasibility of labeling the parathyroid glands for easy identification by administering 5-aminolevulinic acid (5-ALA) orally to patients undergoing endocrine neck surgery, because 5-ALA accumulates in the parathyroid and has a fluorescent metabolite, protoporphyrin IX.
  
  
  METHODS
  Twenty-nine patients about to undergo endocrine (parathyroid or thyroid gland) neck surgery were orally given 5-ALA, a nontoxic substance that occurs naturally in the human body and has no known major side effects. During surgery, we used blue light to excite protoporphyrin IX, the fluorescent metabolite of 5-ALA, and viewed the resulting bright red fluorescence through an optical filter.
  
  
  RESULTS
  In the majority of the patients, the parathyroid glands were defined by a clear fluorescence. In 23 patients with pathological parathyroid tissue, the fluorescence enabled us to identify and completely remove diseased parathyroid tissue. In 3 patients with thyroid disease, we were able to easily remove diseased thyroid tissue, and an accidentally removed parathyroid gland was autotransplanted during surgery.
  
  
  CONCLUSIONS
  In all but a few cases, 5-ALA clearly labeled parathyroid tissue, allowing for its clean removal or preservation according to the purpose of the surgery. This simple, benign technique is extremely useful for identifying parathyroid tissue, whether pathological or normal, during endocrine neck surgery.
authors.affiliation: Department of Thoracic Surgery, Nippon Medical School.
authors.forename: Shingo
authors.initials: S
authors.lastname: Takeuchi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shimizu
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Shimizu
authors.forename: Haruki
authors.initials: H
authors.lastname: Akasu
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Okamura
mesh_terms: D000328:Adult; D000368:Aged; D000622:Aminolevulinic Acid; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000601:surgery*; D010280:Parathyroid Glands / Q000601:surgery; D016105:Parathyroidectomy; D011524:Protoporphyrins; D020775:Thoracic Surgery, Video-Assisted; D013961:Thyroid Gland / Q000601:surgery; D013965:Thyroidectomy
chemical_list: D011524:Protoporphyrins; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX