25.4.1 Lead Poisoning
Lead is a heavy metal, ubiquitous in our environment that has no physiologic role in biological systems. Lead toxicity is a particularly insidious hazard with the potential of causing irreversible health effects associated with chronic toxicity.
Diagnostic Criteria:
The clinical presentation varies widely, depending upon the age at exposure, the amount of exposure, and the duration of exposure
- New born: Be born prematurely, Have lower birth weight, slowed growth,
- Children: Developmental delay, Learning difficulties, Irritability, Loss of appetite, Weight loss, Sluggishness and fatigue, Abdominal pain, Vomiting, Constipation, Hearing loss, Seizures, Eating things, such as paint chips, that aren’t food (pica), lower IQ , anxiety, depression and ADHD Like symptoms
- Adults: High blood pressure, joint and muscle pain, difficulties with memory or concentration, headache, abdominal pain, mood disorders, reduced sperm count and abnormal sperm, miscarriage, stillbirth or premature birth in pregnant women, anaemia, Fanconi’s syndrome, wrist drop
Investigations
- Lead blood levels <10 µg/dL
- Free erythrocyte protoporphyrin (FEP) level
- FBC
- Imaging studies according to presentation,-chest, bones, abdomen etc are ordered as appropriate.
Non-Pharmacological Treatment
- Remove the source of lead exposure
- Closely monitor cardiovascular and mental status
- Maintain an adequate urine output.
- Assess renal and hepatic functions.
Pharmacological Treatment
Blood Lead levels are 25–40 µg/dL
D: Give D-penicillamine 30-40mg/kg/day PO 1-6months, 2hours before or three hours after meals
Blood Lead levels are 45–70 µg/dL Chelate the patient using
D: 2,3-Dimercapto-succinic acid (DMSA or succimer) 10mg/kg by deep IM, 8 hourly for 5 days, followed by 10mg/kg 12hourly for 14 days.
Blood Lead levels of <70 µg/dL and/or encephalopathy
D: Dimercaprol 3mg/kg deep IM 4 hourly for 48 hours followed by 3mg/kg 12 hourly for 10 days
AND
D: Ethylene diamine tetra-acetic acid (CaNa2 EDTA) IV 10mg/kg 8hourly for 5 days
25.4.2 Mercury Toxicity
Mercury in any form is poisonous. Poisoning can result from mercury vapour inhalation, mercury injection and absorption of mercury through the skin
Diagnostic Criteria
- Inorganic Mercury:
- Ash-gray mucous membrane, haematochesia, severe abdominal pain, foul breath, hypovolaemic shock, Metallic taste, stomatitis, gingival irritation loosening of teeth and Renal tubular necrosis
- Organic Mercury:
- Visual distaubances, – Eg, scotomata, visual field constriction, ataxia, paresthesias (early signs), hearing loss, dysarthria, mental deterioration, muscle tremor, movement disorders, paralysis and death (with severe exposure)
Investigations:
- Blood and Urine Mercury levels
- FBC
- RFT
- Hair, Toenail, and CSF mercury level for chronic exposure
- Plain X-ray of the abdomen
Non-Pharmacological Treatment:
- Remove from the exposure
- Airway Breathing and Circulation (ABC)
- Give oxygen
- Copious irrigation of the skin if skin involvement
- Do gastric lavage if ingested mercury and observed in the abdominal radiographs
- Do Hemodialysis when renal function has declined.
Pharmacological Treatment:
A: Activated Charcoal as in ingested poisons
D: 2,3-dimercapto succinic acid (DMSA or succimer) 10 mg/kg PO 8 hourly for 5 days; follow by 10 mg/kg/dose 12hr for 14 days; not to exceed 500 mg/dose
In acute inorganic mercury poisoning:
D: Dimercaprol:
- Day 1: 5mg/kg deep IM once for 1 day
- Day 2–11: 2.5mg deep IM 12 hourly for 10 days
Surgical intervention: To remove mercury that has been logged in the intestine or colon
