Tox: Iron

Question 1

Difference between dose of iron and elemental iron dose.

Answer 1

‘Dose’ of iron you take is not the same as the amount of elemental iron. The amount of elemental iron within the supplement is what determines the toxicity.

Question 2

Toxic dose of iron

Answer 2

> 20mg/kg of elemental iron

Question 3

Mechanism of iron toxicity

Answer 3

Direct corrosive effect on GI tract.
Toxicity from free circulating iron -> cellular uncoupling of oxidative phosphorylation and production of free radicals –> anaerobic metabolism, multiorgan failure

Question 4

Phases of iron toxicity

Answer 4

Phase 1: GI phase
- N/v/d, GIB 2* corrosive effect.
- If no vomiting in first 6 hrs, NO TOXICITY.
Phase 2: Latent phase (6-24 hrs post ingestion)
- Clinical improvement after resuscitation
- Pts with mild toxicity do not progress beyond this stage
Phase 3: ‘Shock’ phase
- Recurrence of GI symptoms
- Anaerobic metabolism -> shock, lactate production, AGMA
- Multiorgan failure
Phase 4: Fulminant hepatic failure (2-3d post ingestion)
Phase 5: Delayed sequelae
- GI scarring inc. strictures

Question 5

How long do you need to monitor patients after iron overdose before you can safely determine there is NO toxicity?

Answer 5

6 hrs. If no vomiting by 6th hr, then there is NO toxicity from iron.

Question 6

Severe toxic iron level

Answer 6

> 90 micromol/L

Question 7

When should serum iron levels be drawn

Answer 7

4-6hrs post ingestion or if SR/enteric coated, 6-8hrs post ingestion.

Question 8

Is measurement of TIBC helpful in the setting of overdose?

Answer 8

No

Question 9

What imaging could be considered

Answer 9

abdominal radiograph may show radio-opaque pills. A negative radiograph does not rule out ingestion

Question 10

Treatment of iron overdose

Answer 10

Whole bowel irrigation for large pill burden (may be limited by vomiting).
Activated charcoal does NOT bind iron.
Deferoxamine for some (consult toxicology before administration).

Question 11

What is the antidote for iron overdose and when/how should it be used?

Answer 11

Deferoxamine (chelating agent).
Indications: systemic illness (severe acidosis, shock), serum iron levels >90 micromol/L.
Consult tox before administration.
Give 15mg/kg (over ?) with gradual increasing doses.

Question 12

What complications can be seen after iron antidote administration

Answer 12

Deferoxamine may cause:

• ‘vin-rose’ urine (renally excreted deferoxamine-iron complexes may cause urine to look pink-red)
• Duration related risk of ALI/ARDS in children
• Rate related hypotension
• Yersinia enterolitica GI infection or sepsis

Question 13

Potential infectious complication of iron overdose

Answer 13

Yersinia enterocolitica GI infection or sepsis