IRON POISONING
INTRODUCTION
Although iron poisoning is the most common cause of death due to poisoning in young children , it is also a significant problem in adolescents and adults.
pharmacokinetic
Total body iron = 3-5gr
Ferrous =70% , myoglobin and hemoglobin
ferric =25% , ferritin and hemosiderin
Transferrin and enzymes =5%
Absorption
duodenom proximal jejunum
Amount of elemental iron in tablets Sufate 300/325mg 20% Fumarate 200mg 33% Gluconate 300mg 12% Mulitivitamins : Children’s chwable 4_18mg/tab Adult 6_50mg/tab Prenatal 36_65mg/tab
Pathophysiology
Iron is potent catalyst of free radical formation and is capable of oxidizing a wide range of substrates ,including lipid, protein,DNA, and various biomolecules.Typical iron poisoning targets: GI CVS Liver CNS Hematopoietic system Metabolic acidosis
GI:abdominal pain,vomiting,bleeding,intestinal
Infarcts
CVS:hypotension,low cardiac out
put,cardiomyopathy,Hypovolemia,hypoperfusion
Liver:hepatic necrosis,hypoglycemic,encephalopathy,
Coagulopathy
Hematopoietic system :coagulopathy
CNS:lethargic,coma,seizure
Metabolic acidosis
Clinical presentation Stage1-GI (0.5-6h):abdominal pain,vomiting,darrhea,
Hematemesis,hematochezia,melena
Stage 2-relative stability(4-12h):GI symptoms improve,subclinical hypoperfusion
Stage 3-shock and acidosis(6-72h):hypoperfusion, metabolic acidosis,coma,coagulopathy,ARDS, potential multisystem failure
Stage 4-hepatic necrosis(12-96h):coma,coagulopathy,
Jaundice
Stage 5-bowel obstruction(2-4w):abdominal pain,vomiting,dehydration
Diagnosis clinical
History
physical exam
laboratory:
1-abdominal radiograph,2-serum iron concentration,3-ABG,CBC,BS,BUN,Cr,Coagulation profiles,LFT,electrolytes,crossmatch
Differential diagnosis:
consider metabolic, structural,infectious and other poisoning with GI symptoms
Iron toxicity
No symptoms for 6h =No toxicity
<300 microgram/dl No toxicity 300-500 mild >500 severe
<20mg/kg only vomiting and nausea
>60mg/kg toxic
Treatment 1.stabilize patient as needed 2.estimate risk for systemic toxicity by
amount of elemental iron 3.IV access 4.laboratory exam 5.GI decontamination:whole bowel irrigation
if tablets are seen on radiograph(PEG 2lit/h in adult,1lit/h in children)
6.chelation
Chelation Iron antidote = Deferoxamine (DFO) = a growth
factor found in the streptomyces pilosus
Mechanis :Fe binding, vinrose(challeng test)
Indications:serum fe>500, notable clinical symptoms(coma, hypovolemia,coagulopathy,metabolic acidosis),many tablets at radiograph,remain symptoms+300-500fe)
Dose: 15mg/kg/h infusion for no longer than 24h and max 30 mg/kg/h
Criteria for stopping therapy:
improving symptoms,Fe<150mic/dl,lack of tablets, normal urine color
Side effects:
hypotension,rash,sepsis,ARDS(>24h)
THE END
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