TOX 5 - Lead Flashcards
Blood effects- chronic
Heme production impaired -> hypochromic microcytic anemia
lead interferes with heme synthesis by inhibiting the incorporation of Fe into protoporphyrin, increases the membrane fragility of erythrocytes,
anaemia, appearance of basophilic stippling (diagnostic clue)
Nervous system effects- chronic
Encephalopathy
Cognitive abnormalities
*in children – minimal brain dysfunction, decreased hearing acuity
*in adults – slowed reaction time, insomnia, anorexia, irritability, etc.
peripheral neuropathy – painless weakness of extensors muscles in hand
Kidney effect
Interstitial damage
Gout
Reproductive
Decreased fertility in women
GI- chronic effect
- loss of apetite
- constipation
- pain
- in higher dose –
- bouts of abdominal pain „lead colic”
- „gingival lead lines” – deposits of lead sulfides
Types of lead poisoning
Organic and inorganic lead poisoning
Acute inorganic lead poisoning
Rare, industrial
GI and CNS symptoms
- acute intoxication is rare
- encephalopathy,
- colic, spastic ileus ,
- hemolytic anemia
diagnosis difficult
Chronic inorganic lead poisoning
Common
Weakness, anorexia, anxiety, tremor, weight loss, headache, GI symptoms, extensor muscle weakness
Blood
GI
Nervous system
Bones
Inorganic lead poisoning
Caused by lead agent in gasoline
Causes acute CNS effects (headache, hallucinations)
Treatment of lead poisoning
- termination of exposure
- chelation therapy (calcium disodium EDTA binds lead and enhances elimination)
Chelation therapy
medical procedure that involves the administration of chelating agents to remove heavy metals from the body
lead Form entering body
- inorganic lead oxides and salts
- organic (tetraethyl lead)
Most frequent source of intoxication- lead
- occupational,
- environmental (batteries, paints, ceramics, etc.)
- antiknock agent in gasoline (organic)
Major route of absorption- lead
- respiratory and
- GI tract,
- skin (organic)
- crosses the placenta
- absorption from GI ~ 10 %, in children 40 %
- enhanced in case of reduced Fe or Ca intake
Pharmacodynamics of lead
- inhibits enzymes via sulfhydryl binding
- interferes with action of cations like Ca, Fe, Zn
- alters the structure of membranes and receptors