A fatal case of iatrogenic iodine poisoning: is point of care chloride a useful iodine surrogate marker?

Abstract

Abstract Severe toxicity from povidone-iodine is rare, causing metabolic acidosis from the conversion of iodine to sodium iodide and direct tissue destruction. We report a case of fatal iodine toxicity following sclerotherapy. An elderly man presented following ablation of a large renal cyst with 10% povidone-iodine and 100% ethanol. He appeared intoxicated however denied alcohol ingestion. Over hours he developed progressive hypotension despite multiple vasopressor agents. Blood gas analysis demonstrated a metabolic acidosis (pH 7.11, bicarbonate 13 mmol/L) with an apparent hyperchloremia of 124 mmol/L. The ethanol concentration was 55 mmol/L (249 mg/dL). Imaging confirmed large volume residual radio-opaque fluid at the procedure site. The fluid was percutaneously drained and dialysis commenced for iodine toxicity. Iodine concentrations peaked at 8940 µmol/L (reference range 0.32-0.63 µmol/L) 14.5 h post exposure. Point of care chloride concentrations remained elevated (peak 129 mmol/L) following the trend of iodine concentrations, normalising once the iodine concentration was 1559 µmol/L. The patient deteriorated despite maximal therapy and succumbed on day 3. Iodide interferes with point of care testing chloride measurements. Point of care chloride concentrations may have a role as a surrogate marker for iodine but only at very high iodine concentrations (>2000 µmol/L).