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Rosen's Toxicology > 151. Fe and Heavy Metals > Flashcards

151. Fe and Heavy Metals Flashcards

1
Q

2 main mechanisms of Fe toxicity

A

(1) direct caustic injury to the gastrointestinal mucosa (resulting in necrosis, bleeding, perforation)
(2) impaired cellular metabolism, primarily of the heart, liver, and central nervous system (CNS). (via uncoupling of oxidative phosphorylation and impairment of ATP synthase; cell membranes are damaged by iron free radicals; iron is an arteriolar/vasodilator; direct myocardial toxin)

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2
Q

3 Preps of Fe and how much in each

A
  1. Sulfate - 20%
  2. Fumarafte - 33%
  3. Gulconate - 12%
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3
Q

Amount of Fe for mild, moderate and severe tox

A
  • Ingesting = 20 mg/kg = no symptoms
  • Mild/moderate toxicity: 20-60 mg/kg
  • Severe: > 60mg/kg
  • LD50 (50% mortality) = 200-250 mg/kg
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4
Q

5 phases of Fe toxicity

A

1 GI 6hr Vomiting, diarrhea, hematemesis, hematochezia Corrosive effect of iron on GI mucosa
2 Latent 6-24hr Resolution of GI sx. Tachycardia, acidosis, altered mental status Ongoing cellular toxicity and organ damage
3 Systemic 12-24hr Return of GI sx, acidosis, leukocytosis, coagulopathy, renal failure, lethargy/coma, CV collapse Iron distributes to the tissues with worsening cellular toxicity and organ damage
4 Hepatic 2-5 days Fulminant hepatic failure, coagulopathy Rapid absoption from portal system with resultant oxidative damage
5 Obstructive 3-6 weeks Pyloric or bowel scarring, obstruction Healing of the injured GI mucosa

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5
Q

Indications for desferoxamine

A
  1. Level > 500

2. Any severe signs and Sx

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6
Q

3 possible complications of desferoxamine

A
  1. HypoT
  2. ARDS
  3. Yersina sepsis
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7
Q

Peds sources of lead

A

Lead dust
Paint in old homes

Parent’s occupation

Imported toys or candies

Foreign body ingestions

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8
Q

Adult lead sources

A

Occupational
Recreational
Meds
Retained bullets

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9
Q

3 body systems poisoned by lead

A

Heme
Neuro
Renal

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10
Q

Presentation by lead levels

A

10 None Decreased IQ
Decreased Hearing

Decreased Growth

20 Increased Protoporphyrin
No symptoms

Decreased nerve conduction
Increased protoporphyrin

30 Increased blood pressure
Decreased Hearing

Decreased vitamin D metabolism
40 Peripheral neuropathies
Nephropathy

Infertility (men)

Decreased Hb synthesis
50 Decreased Hb synthesis Lead colic
70 Anemia Anemia
Encephalopathy

Nephropathy

> 100 Encephalopathy Death

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11
Q

How to Dx lead poisoning

A

Blood lead level
Anemia w/ basophilic stipling on smear
Radio-opaque lead in stomach
Radiographs of wrists and knees may show “lead lines”

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12
Q

Indications for arsenic Tx

A

Any urine level above 100 μg/day or 50 μg/L = treatment

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13
Q

MGMT of arsenic

A

Chelation if symptomatic and suspected exposure
Start as early as possible without waiting for laboratory confirmation
Intramuscular BAL is the preferred chelator
Succimer can be given orally (if tolerates)
d-Penicillamine = lots of side effetcs and inferior to BAL or succimer,
Chelation is not useful for arsine gas exposures
Arsine gas poisoning=exchange transfusion, continuous venovenous hemodialysis, and plasma exchange

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14
Q

Toxic forms of mercury

A

Elemental
Inorganic (salts)
Organic

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15
Q

Sx of acute mercury poisoning

A

Cough, dyspnea, and chest pain
Stomatitis, inflammation of the gums, and excessive salivation
Severe nausea, vomiting, and diarrhea, which can lead to shock
Conjunctivitis and dermatitis

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16
Q

3 chelating agents for heavy metals

A

Desferoxamine -Fe
BAL - Lead, arsenic, Mg
CaNaEDTA - lead
Succimer - Lead, Arsenic, Mercury

17
Q

Fe blood levels and toxicity

A

o <350 – minimal tox
o 350-500 – mod
o >500 severe

18
Q

Indications for lead antidotes in children by lead level

A 
o	45-69
•	if no CNS Sx
•	oral succimer
•	N/V/D
o	>69 
•	admit for IV chelation
•	dimercaperol
o	encephalopathy
•	IV EDTA
•	Also give dimercaperol
19
Q

MGMT of mercury

A
  • AC no use
  • For inhalation remove from area
  • BAL for acute inorganic ingestion
  • Succimer for acute and chronic

Rosen's Toxicology (8 decks)

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