TOX 5 - Lead Flashcards

1
Q

Blood effects- chronic

A

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)

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2
Q

Nervous system effects- chronic

A

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

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3
Q

Kidney effect

A

Interstitial damage

Gout

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4
Q

Reproductive

A

Decreased fertility in women

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5
Q

GI- chronic effect

A
  • loss of apetite
  • constipation
  • pain
  • in higher dose –
    • bouts of abdominal pain „lead colic”
    • „gingival lead lines” – deposits of lead sulfides
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6
Q

Types of lead poisoning

A

Organic and inorganic lead poisoning

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7
Q

Acute inorganic lead poisoning

A

Rare, industrial

GI and CNS symptoms

  • acute intoxication is rare
  • encephalopathy,
  • colic, spastic ileus ,
  • hemolytic anemia

diagnosis difficult

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8
Q

Chronic inorganic lead poisoning

A

Common

Weakness, anorexia, anxiety, tremor, weight loss, headache, GI symptoms, extensor muscle weakness

Blood

GI

Nervous system

Bones

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9
Q

Inorganic lead poisoning

A

Caused by lead agent in gasoline

Causes acute CNS effects (headache, hallucinations)

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10
Q

Treatment of lead poisoning

A
  • termination of exposure
  • chelation therapy (calcium disodium EDTA binds lead and enhances elimination)
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11
Q

Chelation therapy

A

medical procedure that involves the administration of chelating agents to remove heavy metals from the body

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12
Q

lead Form entering body

A
  1. inorganic lead oxides and salts
  2. organic (tetraethyl lead)
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13
Q

Most frequent source of intoxication- lead

A
  • occupational,
  • environmental (batteries, paints, ceramics, etc.)
  • antiknock agent in gasoline (organic)
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14
Q

Major route of absorption- lead

A
  1. respiratory and
  2. GI tract,
  3. skin (organic)
  4. crosses the placenta
  • absorption from GI ~ 10 %, in children 40 %
  • enhanced in case of reduced Fe or Ca intake
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15
Q

Pharmacodynamics of lead

A
  1. inhibits enzymes via sulfhydryl binding
  2. interferes with action of cations like Ca, Fe, Zn
  3. alters the structure of membranes and receptors
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16
Q

lead distribution

A
  • first it bounds to erythrocytes
  • inorganic - soft tissues, redistribution in bones
  • organic - especially liver and CNS
17
Q

inorganic lead distribution

A

inorganic -

  1. soft tissues,
  2. redistribution in bones
18
Q

organic lead distribution

A

organic - especially

  1. liver and
  2. CNS
19
Q

elimination of lead via

A

via kidney ( minor - sweat and feces)

elimination half-life

  • from tissues ~ 12 month
  • from bones ~ 20 years
  • mobilization from bones enhances in case of
    • hyperthyroidism
    • prolonged immobilization
    • on pregnancy, during lactation
    • in postmenopause
20
Q

lead half life in tissue and bone

A

elimination half-life

  • from tissues ~ 12 month
  • from bones ~ 20 years
    • mobilization from bones enhances in case of
      • hyperthyroidism
      • prolonged immobilization
      • on pregnancy, during lactation
      • in postmenopause
21
Q

lead mobilisation from bone enhanced in

A

from bones ~ 20 years

  • mobilization from bones enhances in case of
    • hyperthyroidism
    • prolonged immobilization
    • on pregnancy, during lactation
    • in postmenopause
22
Q

bones effects- chronic

A

– children growth retardation (lead deposits in the epiphysis)

23
Q

acute treatment

A
  • Supportive care
  • first dimercaprol and 4 hours later CaNa2EDTA I.V
24
Q

chronic treatment

A

CaNa2EDTA – I.V infusion (or I.M) for 5 days (CaNa2EDTA is able to remove lead from the bones)

followed by P.O succimer

25
Q

Succimer administration

A

per os

in chronic treatment of lead toxicity

26
Q

CaNa2EDTA administration

A

CaNa2EDTA –

  1. I.V infusion
  2. (or I.M) for 5 days (CaNa2EDTA is able to remove lead from the bones)

in chronic treatment of lead toxicity

27
Q

Organic lead (tetraethyl lead) Major effects

A

CNS effects

  • delirium,
  • convulsion,
  • brain edema,
  • death)
28
Q

Organic lead (tetraethyl lead) treatment

A

Therapy

  1. decontamination from the skin,
  2. symptomatic treatment
  3. No chelators (they are not effective)
29
Q

chelators are not effective in

A

No chelators (they are not effective)

Organic lead (tetraethyl lead) treatment