Iron (Fe)

Background

- in blood fe bound to protein called transferrin. Reticuloendothelial sys removes xferrin from blood and stores fe as ferritin or hemosiderin

- ferum fe lvls- 50- 150 mcg/dl

- TIBC or xferrin lvl 300- 400 mcg/dl

- xferrin saturation 35% +/- 15%

- sys tox due to free Fe- free fe exists once total fe lvl exceeds fe binding capacity of xferrin

- fe normally lost thru bile, sweat, dermal and GI turnover

- causes vomitting, gi bleeds and deposits in liver- can cause coagulopathy and hypoglycemia later on

- can cause sz

- free fe and xferrin are vasodilators and neg inotrope

- can get met acidosis

- free fe goes intracellularly and uncouples mitochondrial electron xport from ox phosphorylation so get cellular asphyxiation.

also may increase lipid peroxidation and get free radicals to cause dysfnction of krebs cycle and e- xprt- theoretically free radical scavenger like vit E may be useful

Diagnosis

PHASES

1- corrosive effect on gut- abd pain, n/v/d,

2- 2- 48 hr- apparent recovery and response to fluids

3- 6- 48 hr- recurrence of gi sys, CV collapse, acidosis, leukocytosis, coagulopathy,

4- 2- 5d, hepatic failure and hypoglycemia

5- delayed sequelae of gi scarring

EVAL OF TOXICITY

- elemental fe determines toxicity, not amount of salt

liquid- 1- 20 mg fe/cc

chewable- 15 mg/tab

fe gluc- 12% elemental fe

fe sulf- 20%

fe fumrt- 33%

Elemental Fe Load=

(#tabs x (mg Fe salt/tab)x(%elemental Fe))/ pt wt

Predicted Tox

< 20mg/kg- nontox

20- 60- mild to mod

> 60- severe

Labs

- get serum fe at 3- 5 hr and repeat @ 6- 8 hr

if less than 350mcg/dl min tox. > 500 mcg/dl- severe

- increased wbc. 15K and gluc >150 early on. If have this, then do defuroxime challenge test- if + admit

- kub with pills. 50mg/kg up to 1 gm im or 10 mg/kg iv and wait for 2 urinations for vin rose color change.

- met acidosis since neg inotrope and have lactic acidosis

Treatment

- lavage

- whole bowel irrigation c golytly

- charcoal ineffective

- defuroxamine- chelates c fe to make ferrioxamine- water soluble and peed out. makes brown/ orange urine

90 mg/kg im up to 1 gm in kids or 2 gms in adults- repeat q 4- 6hrs with daily max of 6 gms

if severe tox, 15 mg/kg/hr

- no compazine since can cause coma in combination c def

- can also dialyze the ferrioxamine

- if asymp for 6 hrs and neg labs, home

Source

6/06 MISTRY