Difference between revisions of "Mercury toxicity"

m (Rossdonaldson1 moved page Mercury Poisoning to Mercury toxicity)
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**Thimerosal (mercury containing preservative found in many vaccines) has '''''NOT''''' been linked to developmental delays or autism
 
**Thimerosal (mercury containing preservative found in many vaccines) has '''''NOT''''' been linked to developmental delays or autism
  
==Lab Diagnosis==
+
==Differential Diagnosis==
 +
 
 +
==Diagnosis==
 +
===Work-Up===
 +
*Urine and blood Hg levels
 +
*CBC
 +
*Chem 7
 +
*Type and screen
 +
*Radiographs
 +
 
 +
===Evaluation===
 
*Urine Hg levels (>25μg/L is elevated) for elemental and organic mercury
 
*Urine Hg levels (>25μg/L is elevated) for elemental and organic mercury
 
**Levels >300μg/L usually symptommatic
 
**Levels >300μg/L usually symptommatic
Line 102: Line 112:
 
*Hair analysis is not sufficient
 
*Hair analysis is not sufficient
  
==Work-Up==
 
*Urine and blood Hg levels
 
*CBC
 
*Chem 7
 
*Type and screen
 
*Radiographs
 
 
==Treatment==
 
==Treatment==
 
*ABC's
 
*ABC's
 
*Decontaminate
 
*Decontaminate
 
===Inhalation injuries===
 
===Inhalation injuries===
*O2
+
*[[Oxygen]]
*May require intubation
+
*May require [[intubation]]
 
===Caustic injuries===
 
===Caustic injuries===
 
*May consider milk or egg whites
 
*May consider milk or egg whites
Line 119: Line 123:
 
*WBI
 
*WBI
 
===Chelation therapy===
 
===Chelation therapy===
*Penicillamine 250mg PO QID x 1-2wks
+
*[[Penicillamine]] 250mg PO QID x 1-2wks
 
**Avoid in renal failure
 
**Avoid in renal failure
*Dimercaprol (BAL) 2.5-5mg IM Q6-12hr
+
*[[Dimercaprol]] (BAL) 2.5-5mg IM Q6-12hr
 
*DMSA 10mg/kg TID x 5days then 10mg/kg BID x 14days
 
*DMSA 10mg/kg TID x 5days then 10mg/kg BID x 14days
  
Line 129: Line 133:
 
*Cognitive performance of children prenatally exposed to "safe" level of methylmercury http://www.ncbi.nlm.nih.gov/pubmed/9600810
 
*Cognitive performance of children prenatally exposed to "safe" level of methylmercury http://www.ncbi.nlm.nih.gov/pubmed/9600810
  
==Source==
+
==References==
 
*Haddad and Winchester's Clinical Management of Poisoning and Overdose
 
*Haddad and Winchester's Clinical Management of Poisoning and Overdose
 
*Goldfrank's Toxicology
 
*Goldfrank's Toxicology

Revision as of 04:03, 28 September 2015

Background

  • Atomic symbol of Hg from latin name hydrargyros which means silver water

Historical Exposures

  1. Hat felters (Elemental)
    • "Mad as a hatter"
  2. Anti-syphilitic agents (Inorganic)
    • "A night in the arms of venus lead to a lifetime on mercury"
  3. Calomel (Inorganic)
    • Mercurous Chloride sold as a teething powder
    • Causes "pink disease"
      • pain and erythema of the palms and soles, irritability, insomnia, anorexia, diaphoresis, photophobia, and skin rash
  4. Minamata Bay, Japan (Organic)
    • Massive exposure to methylmercury from contaminated seafood secondary to industrial dumping of mercury containing compounds
  5. Iraq 1971 (Organic)
    • 95,000 tons of methylmercury coated grain sold for human consumption
  6. Miners and smelters (Elemental)
    • Mostly secondary to exposure to Cinnabar (HgS)
  7. Dental workers through amalgams (Elemental)
    • Clinical effects secondary to exposure to mercury through amalgams is controversial

Common Exposures

  • Industrial
    • Batteries, fungicide
  • Seafood consumption
    • Mostly methylmercury

Exists as three major forms

  • All disrupt sulfhydryl ezymes leading to impaired cellular function

Elemental

  • Liquid metal at room temperature (Think of the Terminator recongealing)
  • 14x more dense than water
  • Volatile and lipid soluble, therefore rapidly absorbed through lungs (approx 70-80%)
  • Oxidized rapidly to inorganic form
  • Poorly absorbed from GI tract
    • Therefor most ingestions are non-toxic

Organic

  • Exists in three major forms:
  1. Long chain
  2. Short chain
  3. Aryl
  • Long chain and Aryl forms are rapidly converted to inorganic forms
  • Short chain forms are highly lipophilic and cross the blood-brain barrier and placenta
    • Metabolized in the liver to N-acetyl-homocysteine-methylmercury which undergoes enterohepatic recirculation

Inorganic

  • Exists as monovalent and divalent
  • Corrosive
  • Chronic exposures lead to accumulation in brain and CNS
  • Found in many batteries, little risk of toxicity from the mercury components s/p ingestion
    • Other dangers exist though!!!
  • The California Department of Public Health issued a health alert on May, 2014 noting mercury poisoning linked to use of skin-lightening or acne Creams from Mexico[1]

Clinical Features

  • Clinical presentation highly dependent on form, concentration and duration of exposure
    • Inhalation of elemental mercury and ingestion of inorganic can cause acute or subacute toxicity
    • Organic mercury more likely causes chronic toxicity

Elemental Mercury

Acute Exposure

  • Metal fume fever
    • Usually self limited course of fever, chills, shortness of breath, metallic taste in throat, lethargy, confusion, vomiting
      • Rarely may progress to respiratory compromise and death
  • Worse presentation in children
    • May develop pneumothorax, pneumomediastinum and interstitial emphysema
  • Small airway obstruction 2/2 desquamation

Chronic Exposure

  • Classic Triad:
  1. Tremor
  2. Gingivitis/stomatitis
  3. Hyperexcitable state/emotional lability
  • Other findings
    • Headache, visual disturbances, peripheral neuropathy, ataxia

Inorganic Mercury

Acute Exposure

  • Primarily toxic through oral route
  • Causes caustic burns
    • Severity dependent on type [Hg(2)Cl vs Hg(1)Cl] and concentration of mercurial salts
      • Mercuric forms [Hg(2)] more toxic
    • Other symptoms include pain, nausea, hematemesis, hypovolemia, ATN
    • Sequelae include renal failure

Chronic Exposure

  • Chronic exposures usually secondary to inhalation exposure
  • Symptoms include renal failure, dementia, acrodynia
    • Acrodynia (AKA pink disease) = painful erythema and edema of hands and feet, rash, tachycardia, hypertension and irritability.
  • Neuropsychiatric disturbances

Organic Mercury

  • Acute and chronic exposures present similarly
    • Acute presentations usually show signs days to weeks after exposure
  • Neuro symptoms predominate
    • Tremor, ataxia, paresthesias, memory difficulties, visual disturbances, hearing loss
  • May also cause thrombocytopenia and agranulocytosis
  • Highly fetotoxic
    • Easily crosses placenta
    • May lead to severe mental retardation (like those with Minamata disease), developmental delay, ataxia and seizures in offspring
    • Controversy exists over exposure from regular diet
      • Albacore tuna may contain up to 0.34ppm of organic mercury
      • Please see Faroe Island and Seychelles studies
    • Thimerosal (mercury containing preservative found in many vaccines) has NOT been linked to developmental delays or autism

Differential Diagnosis

Diagnosis

Work-Up

  • Urine and blood Hg levels
  • CBC
  • Chem 7
  • Type and screen
  • Radiographs

Evaluation

  • Urine Hg levels (>25μg/L is elevated) for elemental and organic mercury
    • Levels >300μg/L usually symptommatic
    • Organic mercury poorly excreted
  • Blood levels for organic mercury
  • Hair analysis is not sufficient

Treatment

  • ABC's
  • Decontaminate

Inhalation injuries

Caustic injuries

  • May consider milk or egg whites
    • Thought to bind Hg
  • WBI

Chelation therapy

  • Penicillamine 250mg PO QID x 1-2wks
    • Avoid in renal failure
  • Dimercaprol (BAL) 2.5-5mg IM Q6-12hr
  • DMSA 10mg/kg TID x 5days then 10mg/kg BID x 14days

See Also

References