Iron Toxicity Workup
- Author: Clifford S Spanierman, MD; Chief Editor: Asim Tarabar, MD more...
The workup for iron toxicity includes the following studies:
Complete blood count (CBC)
Arterial blood gas (ABG) - To assess for metabolic acidosis
Serum electrolytes - For anion gap calculation
Renal function tests
Liver function tests (LFTs)
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).
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.
McGuigan MA. Acute iron poisoning. Pediatr Ann. 1996 Jan. 25(1):33-8. [Medline].
Mowry JB, Spyker DA, Brooks DE, McMillan N, Schauben JL. 2014 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 32nd Annual Report. Clin Toxicol (Phila). 2015 Dec. 53 (10):962-1147. [Medline]. [Full Text].
[Guideline] Höjer J, Troutman WG, Hoppu K, Erdman A, Benson BE, Mégarbane B, et al. Position paper update: ipecac syrup for gastrointestinal decontamination. Clin Toxicol (Phila). 2013 Mar. 51(3):134-9. [Medline].
Tenenbein M. Benefits of parenteral deferoxamine for acute iron poisoning. J Toxicol Clin Toxicol. 1996. 34(5):485-9. [Medline].
Sankar J, Shukla A, Khurana R, Dubey N. Near fatal iron intoxication managed conservatively. BMJ Case Rep. 2013 Jan 31. 2013:[Medline].
Carlsson M, Cortes D, Jepson S, Kansstrup T. Severe iron intoxication treated with exchange transfusion. Arch Dis Child. April 2008. 93(4):321-2. [Medline].
Gumber MR, Kute VB, Shah PR, et al. Successful Treatment of Severe Iron Intoxication with Gastrointestinal Decontamination, Deferoxamine, and Hemodialysis. Ren Fail. 2013 May 1. [Medline].
Ng HW, Tse ML, Lau FL, Chu W. Endoscopic removal of iron bezoar following acute overdose. Clin Toxicol (Phila). 2008 Nov. 46(9):913-5. [Medline].
Haider F, De Carli C, Dhanani S, Sweeny B. Emergency laparoscopic-assisted gastrotomy for the treatment of an iron bezoar. J Laparoendosc Adv Surg Tech A. April 2009. 19 Suppl 1:S141-3. [Medline].
Cerezo A, Costan G Gonzale A, Galvez C , Garcia V, Iglesias E, Reye A, et al. Severe esophagitis due to overload of iron tablets. Gastroenterol Hepatol. Oct 2008. 31(8):551-2. [Medline].
Valentine K, Mastropietro C, Sarnaik AP. Infantile iron poisonings: challenges in diagnosis and management. Pediatr Crit Care Med. May 2009. 10 (3):e31-33. [Medline].
Atiq M, Dang S, Olden KW, Aduli F. Early endoscopic gastric lavage for acute iron overdose: a novel approach to accidental pill ingestions. Acta Gastroenterol Belg. 2008 Jul-Sep. 71(3):345-6. [Medline].