Iron poisoning: symptoms, diagnosis, treatment

Iron poisoning is the main cause of death from poisoning in children. Symptoms begin with acute gastroenteritis, passing into the latent period, then shock and liver failure. The diagnosis is based on the measurement of serum iron, the detection of radiopaque iron tablets in the gastrointestinal tract, or the fact of unexplained metabolic acidosis in patients with other symptoms suggesting iron poisoning. When swallowing large amounts of iron completely washed the intestine and treat the poisoning by intravenous injection of deferoxamine.

Many over-the-counter products contain iron. Among these and prescription drugs containing iron, iron sulfate (20% pure iron), iron gluconate (12% pure iron) and iron fumarate (33% pure iron) are most often found. Children can take tablets containing iron for candy. Multivitamins for pregnant women contain iron and very often cause deadly poisoning in children. In children's chewing polyvitamins, iron is small, and poisoning is rare.

Iron is toxic to the digestive tract, central nervous system and cardiovascular system. The specific mechanism is unclear, but excess amounts of free iron are involved in enzymatic processes and disrupt oxidative phosphorylation, causing metabolic acidosis. Iron also catalyzes the formation of free radicals, acting as an oxidant, when the plasma protein bonds are saturated, iron and water form iron hydroxide and free H ⁺ ions, which also aggravates metabolic acidosis. Coagulopathy can appear both in the early period due to disturbances in the cascade of coagulation, and later due to liver damage. The content of pure iron <20 mg / kg is non-toxic; 20-60 mg / kg causes moderate poisoning, and> 60 mg / kg can cause severe poisoning and complications.

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Symptoms of iron poisoning

In the development of the clinical picture, there are 5 stages, but the symptoms themselves and their development vary. The severity of the symptoms of the first stage usually reflects the severity of the poisoning as a whole; the next stages of the development of symptoms occur only if the symptoms at the first stage were of medium or severe severity.

Stages of iron poisoning 

Stage	Time since the poisoning	Description
I	Less than 6 hours	Vomiting with blood, profuse diarrhea, irritability, abdominal pain, drowsiness. In severe intoxication - tachypnea, tachycardia, arterial hypotension, coma and metabolic acidosis
II	6-48 h	Up to 24 hours, the apparent improvement (latent period)
III	12-48h	Shock, convulsions, fever, coagulopathy and metabolic acidosis
IV	2-5 days	Hepatic insufficiency, jaundice, coagulopathy and hypoglycaemia
V	2-5 weeks	Obstruction of the outlet of the stomach or duodenum due to scarring

Iron poisoning can be assumed after taking several medications (because iron is available in virtually all drugs) and in young children with access to the gland, with unexplained metabolic acidosis or severe hemorrhagic gastroenteritis. Children often share with each other, so it is also necessary to examine the relatives and friends of young children who have taken in iron-containing substances.

Radiography of the abdominal cavity is usually performed to confirm the ingestion of foreign bodies; this helps to detect insoluble tablets containing iron, or iron accumulations. However, chewed and dissolved tablets, liquid preparations based on iron and iron in polyvitamins can not be detected by X-ray. Serum iron, electrolytes and pH are determined 3-4 hours after swallowing. Symptoms such as vomiting and abdominal pain, serum iron concentration> 350 μg / dl (63 μmol / L), iron accumulations visible on the radiograph, or unexplained metabolic acidosis, support the assumption of iron poisoning. Knowing the iron content, you can only assume poisoning, but you can not accurately judge its availability. The total iron binding capacity of serum (OZHSS) in many cases is an inaccurate indicator and can not be used to diagnose serious poisoning. The most accurate method involves sequential measurement of serum iron concentration, HC0 ₃ and pH, then a joint evaluation of the results is made and compares them with the clinical status of the patient. For example, poisoning is suggested with an increased concentration of iron in the blood, metabolic acidosis, worsening symptoms or, more often, in some variants of a combination of these symptoms.

Prognosis and treatment of iron poisoning

If there are no symptoms in the first 6 hours after ingestion, the risk of serious poisoning is minimal. If shock and coma develop in the first 6 hours, the risk of death is approximately 10%.

If the radiopaque tablets are visible on the chest radiograph, a wash of the intestine with polyethylene glycol, 1-2 l / h for adults or 24-40 ml / kg per hour for children is carried out until the apparent accumulation of iron disappears on the repeated radiograph. Gastric lavage is usually useless, a specially induced vomiting empties the stomach more efficiently. Activated charcoal does not adsorb iron and is used only if other toxins have been ingested.

All patients with more severe symptoms than moderate gastroenteritis should be hospitalized. In severe poisoning (metabolic acidosis, shock, severe gastroenteritis or serum iron concentration> 500 μg / dl), deferoxamine is administered intravenously to chelate free ions in the blood plasma. Infusion of deferoxamine is carried out at a rate of up to 15 mg / kg per hour, titrating the dose according to the level of blood pressure. Since both deferoxamine and iron poisoning can reduce arterial pressure, patients receiving deferoxamine intravenously need intravenous hydration.