Heavy Metals Flashcards
____ Lead is more readily absorbed than ____ lead
Organic lead is more readily absorbed than metallic lead
What is the most common source of lead exposure
Lead based paint
Aerial emission from combustion of leaded fuel
Batteries
Insecticide/herbicide
Which species is most likely to have lead toxicosis
Birds, water fowl
What does lead displace
Calcium and Zinc
Why are younger animals more sensitive to lead
Greater GIT absorption
Immature BBB
Which species are more resistant to lead
Goat, Swine, Chicken
What 3 things decrease lead absorption
Calcium, zinc, protein
How is lead absorbed
Active transport using same carrier protein as calcium
If patient is deficient in _____ then lead is more readily absorbed
Calcium
Vit D
Zinc
Iron
Lead absorption is increased by
GIT acidity
How long does lead bind to proteins in soft tissue
4-6 weeks
What is Metallothionein
Chelating liver protein
Sequesters metal ions
Where can lead be reserved for years
bone matrix
Lead targets which tissues
GIT, Blood, CNS
Chronic exposure to lead at low doses inhibits ___ leading to ___
Heme Synthesis leading to anemia
Lead alters the release of
Neurotransmitters (dopamine, acetylcholine, GABA)
Hematologic signs of lead
Anemia, basophilic stippling
Antemortem - whole blood >0.35
Postmortem – Kidney, liver >10ppm
CNS signs of lead
Anxiety, vocalization, head pressing, manic behavior, seizures
Lead signs in birds
Peripheral neuropathy, chronic wasting
Which chelating agent is better
Calcium disodium EDTA
What are some concerns with chelating agents
Renal injury (don't treat >5 days) Binds other minerals (supplement Zinc)
What can be used with Ca-EDTA to enhance excretion and why
Dimercaprol - crosses BBB
Lead lines do not represent ____
lead deposits in bone
What increases zinc release and absorption
Acid - both
Absorption – AAs, peptides, chelating agents
What decreases zinc absorption
Dietary fiber, phytate (P), Ca
Excess zinc interferes with absorption and use of
Cu and Fe
Rapid accumulation of zinc occurs in which organs
Pancreas, liver, kidney, spleen
Clinical signs of zinc in GI, Blood and Kidney
GI - vomit, anorexia, lethargy, pain, diarrhea, pica
Blood - Hemolytic anemia (hemolysis), icterus, hemoglobinuria
Renal - Azotemia (BUN), hypophos
What type of tube is used for zinc analysis
Trace elements tube - dark blue top
What can chelation therapy cause with zinc
May increase zinc redistribution and absorption
** can use Ca-EDTA after removal of source
Which species milk contains no iron
Pig
What deficiency in sows increases risk of iron toxicity in piglets
Selenium and Vit E
Is organic or inorganic iron more toxic
Organic is less irritant
Why is little iron normally excreted
It is bound to transferrin and transported to bone marrow for hemoglobin synthesis
Free iron ions are very reactive and cause _____ and direct damage to _____
Cause free radical lipid peroxidation and direct damage to cell membranes
The primary effects of iron are on which systems
Cadiovascular, GI and liver – leads to shock and death
Clinical signs for acute iron toxicosis
Severe depression, shock, acidosis and death within hours
Stages of acute iron toxicosis
Stage 1 (0-6 hr) - GI upset Stage 2 (6-24 hr) - apparent recovery Stage 3 (12-96 hr) - Most severe signs due to metabolic effects Stage 4 (2-6 wks) - GI obstruction due to fibrosis
How long after ingestion of iron is GI decontamination effective
Within 4 hrs
______ is not effective but ____ can be used to precipitate iron
Activated charcoal
Milk of magnesia
For iron toxicosis when is chelation therapy warranted and what is used
Has ingested >60 mg/kg, serum iron is >500 mcg/dL
Deferoxamine (rapid injection can cause hypotension and cardiac arrhythmias)
