Iron Flashcards
iron is leading cause of fatal poisoning in who
children
ferrous sulfate elemental iron
20%
ferrous gluconate elemental iron
12%
ferrous fumarate elemental iron
33%
absorption of iron
absorbed into mucosal cell and oxidized to ferric acid
regulated by the level of body iron stores
intake 10-20mg only 1-2mg is absorbed
how is iron distributed
in plasma bound to transferrin which is normally 1/3 saturated, normally none free in the plasma
in tissue iron is stored as ferritin
OD effect on absorption
acute corrosive effect of iron on the GIT mucosa enhances absorption
transferrin system may become saturated
elimination of iron
no physiologic mechanism
sweat
bile
desquamation of skin and mucosal surfaces
toxic dose of iron
10-20mg/kg elemental iron
toxicity effects on the gastric intestinal tract
direct corrosive effects on mucosa - ulcer, hemorrhage, edema
actue corrosive effects = perforation and peritonitis which may enhance iron absorption
toxicity effects on liver
electron transport abnormalities
lactate production
glycogen depletion
enzymatic dysfunction - metabolic acidosis, hyperglycemia
result of free iron concentrations in the hepatocyte during first absorptive pass
hepatocellular toxicity: hyperbilirubinemia, aminotransferase abnormalities, coagulopathy, diffused tissue necrosis, disruption of normal metabolic pathways
toxicity effects on cardiovascular
free iron - venodilation, CV compromise, shock
acute volume loss from GIT - vomiting, hemorrhage
direct cytotoxic effects - capillary leakage, plasma loss
toxicity effects on the neurological system
lethargy and weakness
coma
stage 1 local toxicity symptoms .5-6hr after
NV hematemesis abd pain diarrhea severe gastreoenteritis melena lethargy hypotension tachycardia
stage 2 latent period symptoms 6-24hr after
may recover or go onto stage 3
stage 3 systemic toxicity 4-40hr symptoms
pallor cyanosis lethargy hypotension disorientation convulsions coma shock fever leukocytosis hyperglycemia metabolic acidosis
stage 4 2-4 days after symptoms
jaundice hypoglycemia elevated transaminases prolonged clotting times thrombocytopenial hemorrhage renal failure pulmonary edema
stage 5 lat complications 2-8 wks after symptoms
GI obstruction
pyloric stenosis
gastric fibrosis
strictures
<20mg/kg presents as
asymptomatic
20-30mg/kg presents as
self limiting vomiting and diarrhea
> 40mg/kg may be
serious
> 60mg/kg may be
lethal
refer children with a dose_____ to emerg
> 10mg/kg
diagnosis of iron toxicity
history of exposure
vomting, diarrhea, hypotension
iron serum level >350mcg/dL (>500 requires action)
abdominal radiograph
interventions for iron toxicity
ABC basic life support
gastric emptying
activated charcoal not useful
chelators - severe
why is activated charcoal not good for iron OD
metals not absorbed well
agent corrosive so AC will get into the cavity
what is deferoxamine mesylate
specific iron binding ligand
very high affinity for iron
chelates free iron and iron of ferritin but NOT ironbound to hemoglobin or cytochromes
100mg DFO = ____ iron
9mg
iv infusion rate of DFO
15mg/kg/hr
iv removes much more than im
should see change in color of urine
when do you discontinue DFO therapu
patient returns to asymptomatic state after latent period has passed
serum iron <150ug/dL
return to normal urine color
can DFO be used in pregnant patients
yes
DFO adverse effects
histamine release
DFO-iron complex is a growth factor for yersinia enterocolitica that can cause infection
excessive intracellular chelation causes oxidant damage
acute: hypotension, infections, pulmonary toxicity
chronic use of DFO causes
auditory/ocular and pulmonary toxicity
infections
