Oral transmucosal absorption of iodine after intraoral preparation with povidone-iodine prior to oral surgeries: a randomized controlled study in 12 male patients

Introduction Absorption of iodine through skin and an increased incidence of thyroid disorders due to iodophor exposure are reported. However, the risk of oral transmucosal absorption of povidone-iodine after intraoral preparation is not clear. Objective To investigate the possibility of oral transmucosal absorption of povidone-iodine after intraoral preparation and its effect on thyroxine level in blood. Patients and methods A randomized controlled study was carried out in the department of oral and maxillofacial surgery. Twenty- to 40-year-old healthy male adults planning to receive oral surgery under general anesthesia were enrolled. The study group received povidone-iodine irrigation of oral cavity for 3 min as intraoral preparation before operation. The control group received chlorhexidine gluconate irrigation of oral cavity for 3 min as intraoral preparation before operation . Iodine levels in blood and urine, and thyroxine levels in blood were tested and compared, before and after operation. Result(s) In total, 24 patients were included and analyzed finally. We found that after intraoral preparation with povidone-iodine, serum iodine level increased significantly to 2–3 times the pre-operation level in 15–30 min, and the urinary iodine level increased to 5 times the pre-operation level on the first day after operation. Iodine levels in blood and urine decreased significantly on the third day after operation but still significantly greater than the pre-operation levels. However, thyroxine levels were not altered accordingly. Conclusion(s) Oral transmucosal absorption of iodine is observed when povidone-iodine is used for intraoral preparation in healthy male adults, though the free thyroxine in blood is not affected accordingly. Clinical relevance Povidone-iodine is commonly used as an antiseptic in oral surgery and dental clinics. Based on our findings that iodine levels in blood and urine may elevate significantly after intraoral preparation with povidone-iodine prior to oral surgeries, care must be taken for individuals when excess iodine intakes can endanger the safety of the patient. Registration information Name of the trial registry: The Chinese Clinical Trial Registry ( http://www.chictr.org.cn/ ). Registration number: ChiCTR2100042028