Toxicology of Heavy Metals Flashcards
mechanism of toxicity of lead poisoning
- interferes with heme synthesis, DNA transcription, Ca dependent release of NT and protein kinase C (learning and memory)
pathophysiology of lead poisoning
- GI tract and respiratory system are major routes of absorption
- may compete with Ca for a common transport system
- an empty stomach also increases absorption
- about 90% of inhaled lead is absorbed
- 99% of absorbed lead binds hemoglobin
symptoms of acute lead poisoning
- metallic taste and thirst
- milky vomitus
- black stool
- CNS - parasthesia, pain and muscle weakness
- hemolytic crisis
- death usually occurs within 1-2 days
- survivors exhibit chronic symptoms
symptoms of chronic lead poisoning
- wrist drop and foot drop
- anemia
- decreased creatinine clearance
- no sensory deficit but motor neuron degeneration present
diagnosis of lead poisoning
- CaNa2EDTA
treatment of lead poisoning
- stop further intoxication
- chelation therapy indicated at concentrations > 50-60 g/dl
- CaNa2EDTA is 1st line for asymptomatic adult exposure
- symptomatic exposure - CaNa2EDTA with BAL
- D-penicillamine not recommended for adult exposure
pharmacokinetics of arsenic
- human carcinogen
- hair and nails have the highest arsenic concentration in the body
- readily crosses the placenta and fetal injury can occur
skin lesions associated with arsenic poisoning
- melanosis, especially on the trunk and extremities
- hyperpigmentation
- conjunctivitis, skin cancer
- hyperkeratosis, palms and soles
- alopecia, brittle nails
- Mee’s lines
symptoms of chronic exposure to arsenic
- bone marrow depression and impaired folic acid absorption
- folic acid and B12 deficiency, megaloblastic anemia
- muscle weakness
- Mee’s lines
- malignant neoplasms
treatment of aresenic poisoning
- chelation therapy - charcoal, oral penicillamine,
- dimercaprol (BAL) is CI
- dimercaptopropansulfonate (DMPS) is DOC for chronic exposures
pathophysiology of mercury poisoning
- bind sulfhydryl groups
- inhibit enzyme systems and disrupt membrane integrity
symptoms of mercury vapor poisoning
- gingivostomatitis
- tremor
- memory impairment, nervousness, depression, social withdrawal, shyness, timidity, irritability
symptoms of chronic exposure to inorganic mercury
- long term behavioral impairments - attention deficits, memory, motor performance
symptoms of methyl mercury poisoning
- gradual onset of ataxia
- constriction of visual field and dysarthria
diagnosis of mercury poisoning
- 3-4 g/dl
chelation therapy for mercury poisoning
- dimercaprol (for high level exposure) symptomatic patients
- penicillamine (for low level exposure) asymptomatic patients
symptoms of iron poisoning
- abdominal pain, diarrhea or vomiting of brown or bloody stomach contents
plasma iron concentrations
- < 63 mol, no immediate danger
- > 63 mol, deferoxamine should be given
diagnosis and treatment of iron poisoning
- if X-rays show tablets in stomach, vomiting should be induced
