Background: Instant hand warmers and disposable heating pads are commonly used over-the-counter products. The active ingredient is reduced iron which oxidizes when exposed to oxygen, causing an exothermic reaction. Reduced iron is not expected to cause significant toxicity when ingested orally. This supposition, however, is based on a very limited number of human cases. We report a case of accidental heating pad ingestion that resulted in significantly elevated serum iron levels.
Case report: A 52-year-old man opened a “Heat Treat” disposable heating pad thinking it was instant coffee, placed the contents into a cup, added water and drank it. After realizing his mistake the patient was referred to the emergency department (ED) by poison control. A serum iron level 3 h post-ingestion was 308 mcg/dL (normal range 40–150). Coincidentally the patient had an iron level 1 week prior of 142 mcg/dL in a work-up for chronic mild pancytopenia. Plain films revealed high density material within the stomach. Whole bowel irrigation was performed. The patient had a history of chronic abdominal pain, and reported it was worse than baseline. He also complained of nausea but did not vomit. The serum iron level peaked at 373 mcg/dL 6.75 h post-ingestion. Two days post-ingestion the iron level was still elevated at 280 mcg/dL but fell to 91 mcg/dL the next day. The patient’s abdominal pain returned to baseline 2 days post-ingestion and the remainder of his symptoms resolved. The patient was discharged on hospital day 3 with no sequelae after receiving supportive care only.
Case discussion: Reduced iron has been reported to cause little to minimal effects. There have been reports of accidental ingestions of reduced iron with minimal elevations of serum iron, however the elevated levels all returned to normal range within the first 24 h. This case demonstrates it is possible to cause significant elevation of serum iron levels from accidental reduced iron ingestions.
Conclusion: Instant hand warmers and disposable heating pads, when ingested, can result in toxic iron levels. Poison center personnel and emergency physicians should be aware of this effect and patients should be monitored until symptoms resolve and serum iron levels are normal or trending downward.