Iron overdose - Overdose and poisoning

Iron overdose

Definition

Accidental or deliberate overdose of iron salts.

Aetiology

Iron poisoning is usually seen in childhood and results from accidental ingestion of iron-containing medications such as vitamin preparations mistaken for sweets.

Clinical features

Iron causes acute necrotising gastritis. Patients may develop nausea, vomiting, abdominal pain and diarrhoea. In severe poisoning acute upper gastrointestinal bleeding, convulsions and metabolic acidosis may occur. Late signs in severe overdose include hypotension, coma, hypoglycaemia and hepatocellular necrosis.

Investigations

A serum iron level (ideally at 4 hours after ingestion) is the best laboratory measure of severity. Abdominal X-ray may show radio-opaque tablets present in the stomach or small bowel if taken within 2 hours of ingestion. A raised neutrophil count and serum glucose suggests toxicity. LFTs and blood gas measurements should be performed.

Complications

Gastrointestinal perforation or infarction.

Management

In severe poisoning (unconscious or hypotension) intravenous fluids and desferrioxamine (a chelating agent for iron) should be commenced immediately before waiting for serum iron levels. Gastrointestinal haemorrhage may require blood replacement and metabolic acidosis should be corrected. Liver and renal support may be required.

In absence of symptoms, serum levels are monitored every 2 hours until levels fall or symptoms develop. Symptomatic patients with moderate (3–5 mg/L or 55–90 µmol/L) or severe (>5 mg/L or 90 µmol/L) poisoning may require treatment with i.v. desferrioxamine. Patients who have not developed symptoms by 6 hours following ingestion are unlikely to have had a significant overdose and do not require further monitoring.

Within an hour of ingestion of large doses of iron, gastric lavage or endoscopic removal of tablets may be performed.