Lead Flashcards
Understand lead
Most common sources of metal and metalloid poisoning
Lead
Arsenic
Mercury
Sources of lead :
Elemental, inorganic : “moonshine” whiskey contaminated herbal medications indoor shooting ranges ingestion of paint chips lead foreign bodies lead bullets in abdomen or joint spaces
Organic : Leaded gasoline (tetraethyl lead)
Sources of arsenic :
Inorganic (arsenite [trivalent] or arsenate [pentavalent]) :
Insecticides, rodenticides, herbicides, mining
well water contaminated
Ayurvedic and homeopathic medicines
Organic:
Seafood, parasitical medicines (veterinary)
Gas ( arsine ):
Mining smelting/refining, semiconductor industry; made by mixing acids with arsenic-containing insecticides
Sources of mercury :
Elemental :
Battery and thermometer manufacture; sphygmomanometer repair; dentistry; jewelry and lamp manufacture; photography; mercury mining; manufacture of scientific instruments.
Inorganic (mercury salts):
Cosmetic products, especially skin-lightening products; taxidermy; fur processing; tannery work; chemical laboratories; manufacture of explosives, fireworks, disinfectants, button batteries, inks, and vinyl chloride
Organic (methyl mercury, ethyl mercury, and phenyl mercury)
Contaminated seafood; embalming; manufacture of drugs, fungicides, bactericides; handling of insecticides; pesticides, coated seeds; use of chlor-alkali process; working with wood preservatives
Whats the most common source for chronic exposure of lead … ?
United States has banned lead in household paints, gasoline, plumbing systems, food, and drink cans.
Childhood intellectual problems have been highly related to lead exposure. And decreased IQ
Main system affected by lead toxicity :
nervous, cardiovascular, hematopoietic, and renal systems.
Neurological :
- secondary axonal degeneration, mostly of the motor nerves.
- memory and learning deficits
- seizures and coma or develop indolently over weeks to months with decreased alertness and memory progressing to mania and delirium.
- Encephalopathy
cardiovascular system :
increases in the prevalence of hypertension and atherosclerotic vascular
hematopoietic system
interferes with porphyrin m lism, which may contribute to lead-induced anemia and Hemolytic anemia.
colicky abdominal pains
Kidney
- Fanconi’s syndrome with aminoaciduria, glycosuria, phosphaturia, and renal tubular acidosis.
- Chronic interstitial nephritis
- increased uric acid levels
Chronic lead exposure:
- increased calcium deposition at growth plates may be seen as “lead lines” on radiographs of long bones.
- increased fetal wastage, premature rupture of membranes, depressed sperm counts, abnormal or nonmotile sperm, and sterility.
- bluish-gray gingival lead lines.
Characteristic presentation :
- combination of abdominal or neurologic dysfunction with a hemolysis should raise suspicion for lead toxicity.
- any child with encephalopathy of unknown cause
Confirmatory Diagnostic tests :
- Diagnostic studies in the ED should therefore focus on evaluation for anemia and examination of radiographs for evidence of lead exposure.
- blood lead level is the best single test for evaluating lead toxicity, and levels at or >5 micrograms/dL (0.24 micromol/L) are considered elevated in children.
How can radiographs help in diagnosing lead toxicity :
radiographs of long bones, especially of the knee, may reveal horizontal, metaphyseal “lead lines,” which represent failure of bone remodeling rather than deposition of lead.
Clinical manifestations of lead toxicity :
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Treatment :
Chelation :
Chelation therapy for lead toxicity uses dimercaprol
(previously known as British anti-Lewisite), edetate calcium disodium
abbreviated CaNa 2 -EDTA), and succimer
penicillamine, has not received approval for use in the treatment of lead toxicity by the U.S. Food and Drug Administration, but there is published experience demonstrating benefit, and penicillamine is used in Europe for lead poisoning.
What is the guide for chelation therapy :
chelation dosing schedules are guided by the blood lead levels, the presence or absence of symptoms, and the age of the patient.
What should you check before starting chelation treatment ::
The diluent for dimercaprol includes peanut oil, and therefore, dimercaprol should be used with great caution in patients with peanut allergy
