Iodoform medications may cause iodine toxicosis: Two case reports

Objective: Iodine is an essential oligoelement involved in the synthesis of thyroid hormones. Iodine is also used to promote antisepsis and iodoform medications release iodine and are commonly used for septic ulcers and surgery lesions. Few cases of iodine/iodoform toxicity due to systemic absorption from topical/ dermal application have been reported [1,2]. We report two cases of neurologic impairment and transient hypothyroidism induced by excess systemic absorption of iodoform after prolonged and extensive medications. Case series: Case 1. A 64-year-old male hospitalized for COVID-19 pneumonia, presented Klebsiella pneumoniae carbapenemase sepsis associated with decubitus ulcers, that were treated with iodoform gauze medication. After three medications, he developed diarrhoea, xerostomia and lethargy. Blood analysis showed renal impairment with creatinine 3.1 mg/dL and a total calcemia of 11mg/dL. Suspecting iodine poisoning, urine and serum concentrations were performed and were respectively 14,517 μg/L and 2,400 μg/L. Free thyroxine (FT4) was 13.80 ng/L (normal 9.30-17.00), thyroid stimulating hormone (TSH) 6.160 mIU/L (normal 0.270-4.200). A few days later, he died from multiorgan failure. Case 2. A 56-year-old male was admitted to hospital for severe traumatic perianal injury. After surgery, he was stable and treated with iodoform gauze medications, but presented with acute inhibition of thyroid hormone synthesis (Wolff-Chaikoff effect) with TSH 10.500 mIU/L and FT4 16.70 ng/L. Urinary and serum iodine concentrations were 53,500 and 1,087 μg/L, respectively. The patient gradually recovered normal thyroid function after discontinuation of iodoform treatment. Conclusion: Iodine/iodoform poisoning is an underestimated clinical event. Extensive surface and prolonged application are risk factors for developing toxicity. Thyroid function is efficiently regulated even with excessive iodine (Wolff-Chaikoff mechanism). However, in these patients, iodine/iodoform toxicity may be suspected when a new impairment occurs, including disturbance of consciousness, diarrhoea, liver dysfunction, renal failure, and metabolic acidosis. Iodoform (CHI3) is similar to chloroform (CHCl3) in molecular structure and has a similar anaesthetic effect [1]. Moreover, it is lipid soluble and may easily pass the bloodbrain barrier, causing headache, disorientation, delirium and coma. Urinary and serum iodine concentration can be useful in clinical practice to confirm and estimate the degree of toxicity;however, it seems that these values may be higher in iodine and lower in iodoform toxicity.