Flashcards in Iron toxicity Deck (19):
Describe the 5 stages of iron toxicity
GI (abdo pain, N/V/D, hematemesis, melena, lethargy, shock, met acidosis)
Quiescent phase (stop vomiting but developing acidosis)
Met acidosis, renal failure, hepatotoxicity, GI symptoms, CNS dysfxnhypovolemic/distributive/cardiogenic shock
Fulminant hepatic failure: coma, coagulopathy, jaundice
GI strictures, gastric outlet obstruction, bowel obstruction
What are the toxic levels of Fe
20-60 mg/kg toxic
more than 60 mg/kg serious toxicity
what is the pathophys of iron toxicity
disrupts oxidative phosphorylation, decr ionotropy of myocardium, tnhibits thrombin
what symptom indicates serious fe toxicity
vomiting, do not give antiemetics until they vomit
indications for defuroxime
serum level 60-90umol/L and symptomatic
serum level more than 90
what can iron toxicity be treated with
defuroxime until the urine is rose coloured
List common Fe preparations and their elemental Fe content
What causes the coagulation defects seen in iron poisoning?
- Early: Direct effects of vitamin K dependent clotting factors
Late: Hepatic failure and decreased production of clotting factors
List 5 occupations that increase risk of lead exposure.
- Lead smelting
- Battery manufacture
- Radiator repair
- Bridge and ship construction or demolition
- Smoldering or welding
- Cable or tin can production
- Stained glass manufacture
- Lead-crystal or crystal pottery making
- Glass production
- Firing range operation
- Lead based pain abatement
Describe the anemia that is characteristic of lead poisoning?
- Inhibits heme synthesis
- Normochromic or hypochromic
- Severity of anemia correlates with lead BLL
- smear shows basophilic stippling
What diagnostic clue to chronic lead poisoning may be apparent of skeletal x-rays?
- “Lead band/lines” – Increased metaphyseal brightness seen with chronic exposures
What are the indications for chelation therapy in lead poisoning?
- BLL >70 mcg/dL (3.38umol/L)
- Protracted GI symptoms
CNS symptoms from acute exposure
In seriously lead poisoned patients what chelating agents are used?
- Dimercaptol (British antilewisite; BAL) first chelator
Calcium Disodium ethylenediaminetetraacetic acid (CaNa2-EDTA) given with second dose of BAL
What is the pathophysiology of arsenic poisoning?
- Binds sulfhydryl groups, inhibiting critical enzymes in glycolysis
- Disrupts oxidative phosphorylation by replacing phospohorous (arsenolysis)
What strategies can limit or remove arsene?
- Exchange transfusions
- Urinary alkalinization
List chronic effects of arsenic poisoning.
- Mees’ line on the nails
- Painful sensorimotor neuropathy
- Hyperkeratosis of the soled and palms
Anemia (basophilic stippling), leukocytosis or penia, abn u/a, renal or lfts
Which chelators are used in arsenic poisoning?
- Dimercaptol (IM)
- DMSA orally
Which chelating agents are indicated for clinically significant inorganic mercury toxicity?
- BAL (dimercaptol) used for clinically significant inorganic mercury intox but contraindicated in pts with organomercurial poisoning (increases brain merc levels in pts with mentyl merc poisoning)
- Chelation therapy binds the sulfhydryl group that bind mercury after its absorption