Heavy metal toxicity Flashcards Preview

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Flashcards in Heavy metal toxicity Deck (10):

What are the three forms of heavy metals and which is *most toxic?

(1) Elemental - Pb
(2) *Inorganic salts - PbCl2
(3) Organic salts - (C2H5)4Pb


What are three mechanisms of heavy metal toxicity?

(1) Displacement of essential elements (ex. zinc, a cofactor for many enzymes)
(2) Formation of covalent bonds with sulfhydryl and hydroxyl groups (-SH and -OH)
(3) Carcinogenicity - arsenic, chromium, nickel, cadmium


Which heavy metals are carcinogenic?

(1) Chromium
(2) Arsenic
(3) Nickel
(4) Cadmium


What are two modes of treatment for heavy metal intoxication?

(1) Removal of source of exposure
(2) Chelation therapy - only when levels high due to side effects


At what level of lead in blood do you get cognitive impairment?

5 mg/dl blood


What are the effects of lead poisoning?

(1) CNS - (a) impaired mental function in children and (b) lead encephalopathy (hyperactivity, ataxia, neuro deficits, seizures, coma, death)
(2) PNS effects - lead palsy, wrist drop, motor nerve dysfunction
(3) GI effects - abdominal cramps (primary symptom that brings adults to hospital), constipation
(4) Sterility
(5) Hypochromic, microcytic anemia with coproporphyrinogen and aminolevulinic acid (heme synthesis intermediates) in urine
(6) Hypertension


How can lead exposure be monitored?

(1) Coproporphyrinogen and aminolevulinic acid in urine
(2) Blood lead levels
(3) X-ray fluorescence - lead in bone with fluoresce


How can short-term lead exposure be diagnosed? Long term?

Short-term - blood lead levels
Long-term - x-ray fluorescence


What are four lead chelators?

(1) Succimer (most popular) - can be given orally, may cause severe skin rashes and diarrhea
(2) Dimercaprol - can cause hypertension/tachycardia
(3) CaEDTA - Ca exchanged with Pb, can cause kidney toxicity
(4) Penicillamine - can cause bone marrow suppression and allergic reactions to those who are allergic to penicillin


At what lead level should chelators be used for lead toxicity?

45 mg/dl