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