Lead

Question 1

Sources of exposure to lead

Answer 1

• Lead paint Toys and Jewelry Soil Water: Drinking water is also a major source of lead Exposure.
• Occupational sources: Remodeling construction Smelters Battery factories Ammunition.
• Ceramic glazes.

Question 2

Pathophysiology

Answer 2

• Absorption of ingested lead is 10% in adults while it is 50% in children, thus children are at greater risk of toxicity, especially the developing brain. - Lead disturbs multiple enzyme systems. As in most heavy metals, it binds to the sulfhydryl (–SH) group of metabolic enzymes such as those involved in heme synthesis and Krebs cycle.

Question 3

-Lead causes anemia through its decreasing to haemoglobin synthesis by:

Answer 3

*It inhibits conversion of δ aminolevulinic acid (DALA) to porphobilinogen.

*It inhibits conversion of coproporphyrinogen III to protoporphyrin.

*DALA and coproporphyrin accumulate in urine and are used as toxicity markers.

Question 4

Lead increases ………….. as a result of which immature red cells are released into circulation such as

Answer 4

-haemolysis -reticulocytes and basophilic stipped cells.

Question 5

In CNS, lead causes ………… and has a direct cytotoxic effect leading to

Answer 5

• oedema

1. decreased nerve conduction,
2. increased psychomotor activity,
3. lower IQ,
4. and behavioural disorders.

Question 6

Acute toxicity of lead

Answer 6

*Uncommon and results from accidental or intentional ingestion of lead oxides, may present with:

*GIT: metallic taste, vomiting, anorexia, abdominal colic, and constipation

*CNS: lead encephalopathy, behavioral changes, lethargy, fatigue, seizures, and coma

Question 7

Chronic lead poisoning (Plumbism)

Answer 7

Question 8

•In addition chronic lead poisoning causes

Answer 8

renal effects in the form of chronic interstitial nephritis.

Question 9

•Bone effects: classic lead lines in bone x ray as

Answer 9

it triggers hypermineralization

Question 10

Diagnosis of lead Poisoning

Answer 10

Laboratory tests

1.Whole blood Lead levels:

• >45 μg/dL - GI symptoms in adults and children.
• >70 μg/dL - high risk of acute CNS symptoms.
• >100 μg/dL - may be life-threatening.

2. Elevations in free erythrocyte protoporphyrin (FEP) (>35 mcg/dL) reflect lead-induced inhibition of heme synthesis.
3. Urinary DALA can be used as screening test
4. CBC:

• Microcytic hypochromic anemia, reticulocytosis, hemolysis
• Blood film: basophilic stippling of RBC

4. Renal functions

Bone X ray:

•Lead lines: These are actually areas of arrested bone growth.

Question 11

Treatment of lead Acute toxicity

Answer 11

Acute toxicity

I- Emergency measures (ABCD)

II- Elimination

Induction of emesis or GL if ingested

III- Chelation: (see below)

IV- Symptomatic treatment

• IV fluids for dehydration
• Calcium gluconate for lead colic

Encephalopathy: care of coma and convulsions and mannitol to decrease ICT.

Question 12

Treatment of lead Chronic toxicity

Answer 12

Chronic toxicity

I- Prophylactic

• Prophylactic measures to decrease exposure, using masks, gloves …etc.
• Periodic medical examination of workers

II- Curative

I- Stop further exposure

Question 13

Chelation therapy

Answer 13

Question 14

Symptomatic treatment of lead posioning

Answer 14

• Treatment of anemia: blood transfusion
• Renal affection: hemodialysis
• Splint and physiotherapy for wrist and foot affection