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Iron Toxicity Workup

  • Author: Clifford S Spanierman, MD; Chief Editor: Asim Tarabar, MD  more...
 
Updated: Dec 04, 2015
 

Laboratory Studies

The workup for iron toxicity includes the following studies:

  • Serum iron
  • Glucose
  • Complete blood count (CBC)
  • Serum lactate
  • Arterial blood gas (ABG) - To assess for metabolic acidosis
  • Serum electrolytes - For anion gap calculation
  • Renal function tests
  • Liver function tests (LFTs)
  • Coagulation studies
  • Lipase and amylase levels - Occasional patients experience pancreatic injury
  • Pregnancy test in women of childbearing age
  • Blood type and cross-matching
  • Ferritin levels - Helpful for diagnosing chronic toxicity; levels may exceed 1000 mcg/L

For serum iron measurement, samples should be drawn at least 4 hours postingestion, to allow levels to reach steady state; however, levels drawn more than 6 hours after ingestion may underestimate toxicity because of ferritin binding and redistribution of iron. The significance of results is as follows:

  • In adults, levels may not correlate well with the clinical presentation
  • Mild-to-moderate toxicity generally manifests at levels of 350-500 mcg/dL
  • Persistently symptomatic patients with serum iron levels higher than 350 mcg/dL should be admitted
  • Hepatotoxicity usually is observed at levels higher than 500 mcg/dL
  • Levels higher than 800 mcg/dL are associated with severe toxicity
  • Patients with serum iron levels higher than 1000 mcg/dL should be in a facility that can provide age-appropriate intensive care

Glucose levels exceeding 150 mg/dL are common with severe iron toxicity. Following glucose levels is important because hepatic dysfunction may cause hypoglycemia.

On the CBC, a white blood cell (WBC) count of more than 15,000/mm3 is associated with severe iron poisoning. A CBC is also helpful because anemia from blood loss may develop.

LFTs are indicated because hepatic dysfunction is common in severe iron poisoning. The liver is the first organ outside of the GI tract to receive a large iron load, which enters through the portal blood supply.

Electrolyte measurements and renal function tests assist in calculation of the anion gap (see the Anion Gap calculator) and detection of electrolyte abnormalities and the presence of prerenal azotemia. Iron toxicity is one of the causes of acidosis with an increased anion gap, as noted in the mnemonic MUDPILES (M-methanol; U-uremia; D-diabetic ketoacidosis, alcoholic ketoacidosis; P-paraldehyde, phenformin; I-iron, isoniazid; L-lactic [ie, carbon monoxide, cyanide]; E-ethylene glycol; S-salicylates).

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Imaging Studies

Iron tablets remain radiopaque for a few hours postingestion, and may be visible on a kidneys, ureters, bladder (KUB) film. However, the absence of radiopacities does not rule out a significant or even potentially lethal ingestion.

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Contributor Information and Disclosures
Author

Clifford S Spanierman, MD Consulting Staff, Departments of Emergency Medicine and Pediatrics, Lutheran General Hospital of Oak Brook, Advocate Health System

Disclosure: Nothing to disclose.

Specialty Editor Board

John T VanDeVoort, PharmD Regional Director of Pharmacy, Sacred Heart and St Joseph's Hospitals

John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists

Disclosure: Nothing to disclose.

John G Benitez, MD, MPH Associate Professor, Department of Medicine, Medical Toxicology, Vanderbilt University Medical Center; Managing Director, Tennessee Poison Center

John G Benitez, MD, MPH is a member of the following medical societies: American Academy of Clinical Toxicology, American Academy of Emergency Medicine, American College of Medical Toxicology, American College of Preventive Medicine, Undersea and Hyperbaric Medical Society, Wilderness Medical Society, American College of Occupational and Environmental Medicine

Disclosure: Nothing to disclose.

Chief Editor

Asim Tarabar, MD Assistant Professor, Director, Medical Toxicology, Department of Emergency Medicine, Yale University School of Medicine; Consulting Staff, Department of Emergency Medicine, Yale-New Haven Hospital

Disclosure: Nothing to disclose.

Additional Contributors

David C Lee, MD Research Director, Department of Emergency Medicine, Associate Professor, North Shore University Hospital and New York University Medical School

David C Lee, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American College of Medical Toxicology, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

References
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  4. Tenenbein M. Benefits of parenteral deferoxamine for acute iron poisoning. J Toxicol Clin Toxicol. 1996. 34(5):485-9. [Medline].

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