Systematic review of intravenous methylene blue in parathyroid surgery

Background: Methylene blue is an intraoperative adjunct for localization of enlarged parathyroid glands. The availability of preoperative and other intraoperative localization methods, and the reported adverse effects of methylene blue make its routine use debatable. The aim of this study was to perform a systematic review of the use of methylene blue in parathyroidectomy.

Methods: A systematic review of English-language literature in MEDLINE and Scopus databases on the use of intravenous methylene blue in parathyroid surgery was carried out.

Results: There were no randomized clinical trials. Thirty-nine observational studies were identified, of which 33 did not have a control arm. The overall median staining rate for abnormal parathyroid glands was 100 per cent. The median cure rates in the methylene blue and no-methylene blue arms were 100 and 98 per cent respectively. Neurotoxicity was reported in 25 patients, all of whom were taking serotonergic medication.

Conclusion: Observational evidence suggests that methylene blue is efficacious in identifying enlarged parathyroid glands. Toxicity appears to be mild in the absence of concomitant use of serotonin reuptake inhibitors. The effectiveness of methylene blue in the context of currently used preoperative and intraoperative localization techniques has yet to be shown.