If the amount ingested is known, then the amount of elemental iron is calculated per kilograms per body weight (described above). An intake > 60 mg/kg is associated with severe complications.
Onset of hepatotoxicity is usually within 24 hours (in all patients by 48 hours) after an untreated ingestion.
Clinical features of hepatotoxicity:
(1) progressive hepatomegaly
(2) jaundice
(3) coma
These changes will be associated with significant increases in the liver transaminases and total serum bilirubin. In severe cases the patient will die unless a liver transplant is performed.
A flat plate of the abdomen can identify the location and number of ingested iron pills in significant ingestions.
Tenebein et al reported that the lowest acute (within 4 hours of exposure) serum concentration associated with hepatotoxicity was 1700 µg/dL (17 mg/L) when the normal reference range of 50 - 150 µg/dL. This level is >= 11.33 the upper limit of the normal reference range.
where:
• The molecular weight of iron is 55.8 grams.
Liver biopsy in a patient with hepatotoxicity will show hepatocellular necrosis in the periportal hepatocytes (Zone 1).
Management:
(1) Whole bowel irrigation (WBI) is performed if the patient presents soon after the ingestion. This is continued until the rectal outflow is clear and there is no evidence of pills seen on a flat plate of the abdomen.
(2) If the patient presents some time after the ingestion then gastrointestinal injury may have occurred due to iron toxicity. WBI at this point can be hazardous since it may cause hemorrhage, obstruction or perforation. Continuous arteriovenous hemofiltration may be initiated if WBI is contraindicated.
(3) An intravenous infusion deferoxamine is administered at a rate of 15 mg/kg/hour or greater.
(4) If massive necrosis occurs then liver transplant may be necessary.
