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You are here: Home / 14. Toxicology / Heavy Metals

Heavy Metals

July 14, 2011 by CrashMaster

Iron

In normal states, iron is never free in the blood

In overdose, transferrin is overwhelmed and free iron can be found in blood.

No mechanism to get rid of excess iron in body

>20 mg/kg is toxic, >60mg/kg=severe toxicity

Caustic to GI tract.  GI Bleeding

Vasodilator, intereferes with oxidative phosphorylation, neg. inotrope

Acidosis from release of H+ when Fe3 to Fe2 and lactate from electron chain disruption.

 

FSG359-mnemonic to remember tablet contents, Fumurate=1/3=33%, Sulfate=1/5=20%, Gluconate=1/9=12%

 

Phase   I:  0-6 hrs GI, Met Acidosis, Shock, Coma, Bloody Vomit

Phase  II:  2-48 hrs Latent, appear well. May or may not progress (Smoldering)

Phase III:  6-48 hrs Coma, Coag Problems, Shock, Renal Fx.  Normal Iron levels

Phase IV:  2-5 Days  Hepatic Failure

Phase  V:  2-6 weeks GI Scarring

 

Poisoning without emesis is very uncommon

Deferoxamine gives vin rose urine if iron present

 

Draw Serum Iron level, TIBC not helpful.  >350 mcg/dl=toxic, >500 severely toxic

 

AC does not bind

Use Lavage, however iron can erode through gastric mucosa and clump, forming bezoar, must be surgically removed.

Iron is radio-opaque, so consider ABD X-Ray

Whole bowel irrigation

Get Baseline Urine Sample before deferox

Deferoxamine:  do not give c compazine.  Do not give more than 24 hours.  Can give 1 gm as a challenge dose (careful, rapid admin causes hypotension) Get second urine specimen and compare to the first.  If both negative, send home

Dose  15 mg/kg/hr, start first hour at 5 mg/kg/hr to minimize hypotension. Interestingly, the daily dose of deferoxamine can only chelate 56 mg of elemental iron, so its effects must be on a very small amount of free iron.  Can also cause ARF.  Growth of yersinia enterocolitica b/c needs siderophore to provide iron for growth.

Draw Kidney, Liver and Coags

Iron + Deferoxamine is dialyzable

Long term-must get GI f/u studies in weeks to come, possibility of iron-deficiency anemia

If asymptomatic, can send home after 6 hours of observation

Lead

Plumbing from plumb the latin word for lead

Lead+Tin=Pewter

Retained bullets can lead to lead poisoning

Normo or hypochromic anemia c basophilic stippling

pure motor neuropathy c wrist or foot drop

Get ABD and Femur X-rays

Whole blood level and EP level to help c chronic vs. acute

DMSA or BAL then EDTA

Organic lead poisoning is from gasoline inhalation or ingestion

Arsenic (As)

A popular poison in France a few centuries ago, they would feed arsenic to toads and then distill the fluids from the dead body, hence the French name venin de crapaud

Nontoxic organic arsenic is found in seafood, can give false positive urine testing

Present in the chemotherapy drug arsenic trioxide (trisenox) used for acute promyelotic leukemia

Acute overdose=delirium, neuropathy, QT prolongation, ARDS, hemolysis, hyperpigmentation, seizures, progressing to multiorgan failure and coma

gastroenteritis followed by multisystem organ fx

Uncouples oxidative phosphorylation, blocks mitochondrial enzymes.

Mee’s lines on nails

ABCS

Give AC

ABD X-Ray

PEG if any residual arsenic

British AntiLewisite (BAL), developed in response to the Arsenic containing chemical warfare weapon, Lewisite

DMSA for chelation therapy after gi tract decontaminated

Mercury (Hg)

Pliny called it Hydragyrum, hence Hg

Elemental mercury=quicksilver, dangerous only if inhaled, gives sx similar to metal fume fever

Organic form is toxic when ingested

Inorganic toxicity is from ingestion or dermal exposure.  Immediate BAL IM to block renal absorbtion and resultant ATN

Corrosive effects, multiorgan failure to coma

Pink’s disease. Probably an allergic rxn to Hg, associated with interior paints and Hg containing creams.  Skin and mucus symptoms akin to Kawasaki’s

Mad as a Hatter, from hat makers exposed to Hg used to straighten fibers

ABCs

AC will bind

DMSA for chelation

Thallium

Used as rodenticide in other countries

Gets taken up into cells by potassium transport

N/V, diarrhea, pleuritic chest pn then hours later exquisitely painful ascending neuropathy progressing to coma with myocardial necrosis

rapid, progressive peripheral neuropathy with or without alopecia

great poison, as odorless, tasteless, fully dissolvable, and not routinely screened for

MDAC b/c of enterohepatic circulation

Consider Prussian blue as chelator

Metal Fume Fever

Inhalation of zinc, iron, or copper fumes

SOB, Chest Pain, Cough, usually on Monday morning after a weekend off (Monday Morning Fever)

 

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Filed Under: 14. Toxicology


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