Acute iron toxicity
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Transcript of Acute iron toxicity
Acute iron toxicity in childrenDr Hanan Fathy Abdel Aziz Prof of clinical toxicology Ain Shams University
First Clinical Sinario Four years old child presented to the ER
complaining of blood tinged vomitus , abdominal colic and diarrhea of sudden onset started tow hours ago . Past and family history were negative as well as neonatal history.
General examination was negative except for hypotension, 90 over 55 mmHg .
Abdominal examination revealed lax abdomen with no guarding rigidity , and generalized tenderness all over the abdomen more in the upper quadrant.
what is your first differential diagnosis?
Keep it in mind
The ER physician prescribed anti emetic and analgesic.
The child was put under observation then discharged after stabilization of his clinical condition after 4 hours. Before discharge the pediatrician advised the mother to do stool analysis.
Eight hours later the child presented again by his mother by severe diarrhea and disturbed consciousness, on examination , T 35 , P 135 regular rate and rhythm , B.P was 65 over 30 mmHg. Skin was cold and sweaty with cold extremities and very weak distal pulsations , and Inspite of pale mucous membranes jaundice could be noticed.
Lab workup revealed PH 7.0 , HCO3 was 8 mlEq/l ALT and AST , elevated more than 3 folds of normal , both direct and indirect bilirubin are elevated and K level was 2.5 mlEq/l.
The child was admitted to the ICU and resuscitated but his condition deteriorated within hours ended by death.
Second Clinical Sinario A similar case was presented to another hospital
but in this time the pediatrician put the patient under observation and after 4 hours he performed liver enzymes test. Liver enzymes were double normal elevated.
From the history he suspected iron toxicity. By taking detailed drug history form the mother,
she said that she has multivitamin tablets in the home pharmacy and she is not sure if her child ingested some of these tablets or not.
The physician asked for blood iron level , the result was 520 microgram/dl.
After this result the mother told the truth.
The mother was tending to her newborn infant when the child grabbed his mom's bottle of iron pills (ferrous sulfate 325 mg) from the counter. The iron pill contains 65 elemental iron per pill. He ate them thinking they looked like candy. There were 15 tablets missing this means 975 elemental iron ingested.
Physician performed abdominal plain x ray that revealed radiopaque tablets in the stomach and intestine.
What are The Pediatrician Mistakes in The First Case?
Keep it in your mind
Management of Acute Iron Toxicity
First Step in Management is Diagnosis
To diagnose acute poisoning you have firstly to be minded
by acute poisoning
Diagnostic Work up:
Patients Requiring Assessment Ingestion of > 40 mg/kg elemental iron.
(approximately > ½ tablet/kg or 6.5 ml syrup/kg).
Ingestion of an unknown quantity.Any symptomatic patients
The following investigations should be done:
Diagnostic investigation: Abdominal XR (if tablets ingested). Serum iron.Serum iron level: Serum iron levels generally correlate with clinical
severity and are as follows: Mild - Less than 300 µg/dl Moderate - 300-500 µg/dl Severe - More than 500 µg/dl
Difficulties in interpretation of serum iron levels
Serum iron level reaches its peak at 4-6 hours post ingestion, and time from ingestion is often unknown.
Serum levels obtained more than 8-12 hours post ingestion may not be useful because iron redistributes into the tissues.
In case of slow release or enteric coated tablets, levels should be repeated at six to eight hours as absorption may be erratic.
Once Desferoxamine is started , it interferes with standard assays and leads to falsely decreased iron levels.
Is TIBC Useful In Diagnosis Of Acute Iron Toxicity?
TIBC should not be used to evaluate cases of iron overdose. It measures iron bound to transferrin so, This is because lab method used to measure it are inaccurate in overdose and desferoxamine interferes with its measurement
Prognostic investigations: ABG (acidosis). Glucose (hyperglycaemia). Complete CBC. Serum electrolytes, blood urea nitrogen (BUN),
and glucose. ALT , AST and bilirubin. Prothrombin and partial thromboplastin time. Clotting (reversible early coagulopathy and late
coagulopathy secondary to hepatic injury)
Parameters of Severity: Anion gap metabolic acidosis is an important, but
nonspecific, predictor of iron toxicity. Although leukocytosis and hyperglycemia are
non specific for acute iron toxicity , they are only associated with serum iron levels greater than 300 mcg/dl. Consequently , their absence doesn’t exclude acute iron toxicity but their presence indicates severity of the case.
Treatment of Acute Iron Toxicity
Decontamination:Charcoal is of no benefit.Decontamination of choice is whole bowel
irrigation (WBI) with naso-gastric colonic lavage solution 30 ml/kg/hr until rectal effluent clear.
WBI is contraindicated if there are signs of bowel obstruction or hemorrhage.
Poly ethylene glycol
Antidote: Desferoxamine is a chelating agent which forms
with iron a water soluble complex. Consider desferoxamine if:
Serum iron levels > 90 micromol/l. Level 60- 90 micromol/l but tablets are visible
on X ray . Symptomatic patient e.g nausea, vomiting,
hematemesis, fever, altered consciousness, acidosis etc…
Worsening symptoms irrespective of ingested dose or serum iron level in this case Do not wait for iron level start Desferroxamine without delay.
Dose: It is given 15 mg/kg/hr I.V. maximum
35 mg/kg per hour, based on the severity of clinical symptoms.
Desferoxamine - iron complex is renally excreted. If oliguria or anuria develop, peritoneal dialysis or haemodialysis may become necessary to remove desferroxamine.
Because of the kinetics of iron absorption and the possibility of lung toxicity with administration of desferoxamine, consultation with a medical toxicologist and/or regional poison control center is recommended.
When To Stop Desferoxamine? There is no specific guidelines about duration
of desferoxamine treatment but Recommendations have used resolution of clinical symptoms and normalization of lab investigations as the end point for stopping therapy. This may lead to prolonged treatment with increase the risk of lung toxicity.
So , decision to stop desferoxamine therapy should be made according to clinical toxicologist and/or regional PCC, guided by the patient's clinical status.
Urgent stop of desferoxamine: Desferoxamine should be stopped urgently if
pulmonary toxicity appears , and should be used with caution if indications persist >24 hours.
Pitfalls In Management 0f Acute Iron Toxicity
Inadequate hydration of the patient. Failure to recognize patients in the latent phase. Excessive reliance on the SIC, TIBC, or abdominal
radiograph in diagnosis and management decisions.
Inadequate desferoxamine dose. Inappropriate discontinuation of desferroxamine. Prolonged use of desferroxamine (more than 24
hours)
Discussion of first Clinical Sinario
Mistakes of first Pediatrician
He didn’t pay attention to the most important 2 words in the history:
Sudden onset – Blood tinged vomitus He didn’t think about toxicological cause. He had to put In mind that the mother may deny
child ingestion for fear of medico legal or social responsibilities.
Thank you